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Skandalakis’ Surgical Anatomy > Chapter 25. Male Genital System >

Male Genital System: Introduction

Organs

The male genital system consists of the following genital organs:

 

Testis

Ejaculatory duct

Epididymis

Prostate

Ductus deferens (vas)

Bulbourethral gland

Spermatic cord

Male urethra

Scrotum

Penis

Seminal vesicle

Testis, Epididymis, and Spermatic Cord

History

The anatomic and surgical history of the male genital system is shown in Table 25-1.

Table 25-1. Anatomic and Surgical History of the Male Genital System

Testes, Epididymis, and Scrotum 
Albert von Haller 1749 Stated that testes descend from abdominal cavity to scrotum through “vagina cylindrica”
K.F. Wolff 1759 Described mesonephric duct
John Hunter (1728-1793)   Stated that during embryonal life, testes descend from retroperitoneal area to scrotum; cryptorchid gonads do not descend due to dysgenesis; first to use term “gubernaculum”
B.W. Seiler 1817 Interpreted action of gubernaculum as power for testicular descent
J. Müller 1825 Discovered paramesonephric duct
E.H. Weber 1847 Theorized that balloonlike swelling of gubernaculum is main force for testicular descent
C. Weil 1884 Rejected Weber’s theory of involvement of gubernaculum in testicular descent, attributing descent to increased intraabdominal pressure
H. Klaatsch 1890 Proposed conus inguinalis as key factor in testicular descent
Neuhauser 1900 Argued that scrotum is sexual signal to female of capability to produce offspring
O. Frankl 1900 Studied testicular descent
C.R. Moore 1924 Observed degradation of intratubular epithelium in congenital and experimental cryptorchidism; thermoregulatory theory of testicular descent
E.R.A. Cooper 1929 Disputed Hunter’s theory of cryptorchid dysgenesis; reported that cryptorchid testes in very young children were histologically normal
B. Schapiro 1931 Hormonal treatment for cryptorchidism
F. Rost 1934 Used water-soluble extracts of anterior pituitary hormone to induce testicular descent in rodents
A. Müller 1938 Stated that scrotum is an act of self-creativity in male body
A. Portman 1938 Supported Müller’s theory; expression of male sex developed apart from any evolutionary or thermoregulatory factor
L. Moscowitch 1938 Hypothesized that posterior vesical ligament was responsible for failure of testicular descent
T. Martins 1943 Stated that administration of androgens (testosterone), not contractile forces, was cause of testicular descent 
Busch & Sayegh 1963 Performed lymphography of testicle. Recognized and reported concept of primary and secondary nodes, and noted importance in surgical management of testicular carcinoma.
F. Hadžiselimović 1980, 1983 Described role of epididymis in testicular descent
M.K. Backhouse 1981 Experimental confirmation of Martins’ theory; no histological evidence of paratesticular degeneration of gubernaculum
Chris F. Heyns, John M. Hutson 1987 Gubernaculum involvement in testicular descent

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Testes, Epididymis, and Scrotum Table

Busch FM, Sayegh ES. Roentgenographic visualization of human testicular lymphatics: a preliminary report. J Urol 1963;89:106-110.

Hæger K. The Illustrated History of Surgery. London: Harold Starke, 1989.

Hadžiselimović F. History and evolution of testicular descent. In: Hadžiselimović F (ed). Cryptorchidism: Management and Implications. New York: Springer-Verlag, 1983.

Heyns CF, Hutson J. Historical review of theories of testicular descent. J Urol 1995;153:754-767.

Garrison FH. History of Medicine, 4th ed. Philadelphia: WB Saunders, 1913; p. 452.

O’Rahilly R, Müller F. Human Embryology & Teratology, 2nd ed. New York: Wiley-Liss, 1996; p. 450.

Ductus Deferens (Vas) 
Sir Astley Cooper 1823 First experimental work on vasectomy in dogs
H.C. Sharp 1909 Reported benefits of vasectomy in patients with “the habit of masturbation”
E. Steinach 1927 Advocated vasectomy as “rejuvenation operation”
L. Shun-Quiang 1974 Developed the no-scalpel vasectomy; introduced to West in late 1980s

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Ductus Deferens Table

Lipshultz LI, Benson GS. Vasectomy-1980. Urol Clin North Am 1980;7:89-105.

Sharp HC. Vasectomy as a means of preventing procreation in defectives. JAMA 1909;53:1897.

Shun-Quiang L. Vasal sterilisation techniques; teaching material for the National Standard Workshop. Chonguing, China: Scientific and Technical Literature Press, 1988:176.

Steinach E. Biological methods against the process of old age. Med J Rec 1927;125:77.

Seminal Vesicles and Ejaculatory Ducts 
Gabriele Falloppio (1523-1562)   Proved the existence of the seminal vesicles
Zinner 1914 First report of congenital cysts of the seminal vesicle with associated renal dysgenesis
Aboul-Azin 1979 Studied and reported on the anatomy of the seminal vesicles and the ejaculatory ducts
Nguyen et al. 1996 Studied and reported on the anatomy of the ejaculatory duct
Okubo et al. 1998 First report of in vivo endoscopy of the seminal vesicle

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Seminal Vesicles and Ejaculatory Ducts Table

Aboul-Azin TE. Anatomy of the human seminal vesicles and ejaculatory ducts. Arch Androl 1979;3:287-292.

Mettler CC. History of Medicine. Blakiston: Philadelphia, 1947.

Nguyen HT, Etzell J, Turek PJ. Normal human ejaculatory duct anatomy: a study of cadaveric and surgical specimens. J Urol 1996;155:1639-1642.

Okubo K, Maekawa S, Aoki Y, Okada T, Maeda H, Arai Y. In vivo endoscopy of the seminal vesicle. J Urol 1998;159:2069-2070.

Zinner A. Ein Fall von intravesikaler Samenblasenzyste. Wien Med Wochenschr 1914;64:605.

Prostate 
Herophilus of Chalcedon 300 BC First to use term “prostate,” because of organ’s location “standing before” urinary bladder
Galen (AD 130-200)   Reported findings of Herophilus
Nicolo Massa 1536 Anatomic studies (Padua)
Andreas Vesalius (1514-1564)   Anatomic studies
Civillard 1639 Performed first perineal prostatic resection
Jean Zulema Amussat 1832 Removed part of prostate through suprapubic cystotomy
Louis August Mercier 1837 Penetrated prostate through perineum by “prostotome”
Max Nitze 1877 Produced cystoscope with lenses and electric lighting (Berlin)
A.F. McGill 1889 Reported 37 prostatectomies through bladder from above (Leeds)
Belfield 1890 Reported on 133 cases of partial prostatectomy by suprapubic or perineal approach; performed perineal, suprapubic prostatectomies with mortality rate of 14% in 80 cases (Chicago)
Goodfellow 1891 Performed first total perineal prostatectomy (removal of adenoma only)
Fuller 1894 Performed first total suprapubic prostatectomy
J.N. Langley and H.K. Anderson 1894-1896 Studied extrinsic innervation of prostate
H.H. Young 1904 Performed first radical perineal prostatectomy
1909 Introduced clod punch operation for prostatectomy
Van Stockum 1909 Performed first simple retropubic prostatectomy
O.S. Lowsley 1912 Detailed anatomic work on prostate which dominated anatomy and surgery for approximately 50 years
Jean Casimir Felix Guyton (1831-1920)   Pioneered prostatic surgery; first to use Giviole cystoscope
Millin 1945 Popularized simple retropubic prostatectomy
Flocks 1952 Popularized interstitial colloidal gold treatment for prostate cancer
L.M. Franks 1954 Reported that benign prostatic hyperplasia arises in central zone, cancer in peripheral zone
Liebel, Bovie, Stern, Bumpus, R. Wappler, McCarthy, Foley, F. Wappler, Curtiss, Nesbit, Hirschowits, Peters 1924-1957 All made important advances in development of transurethral resection of prostate
Carlton 1965 Combined interstitial gold 198 and external beam irradiation
Charles Huggins 1966 Won Nobel Prize: antiandrogen therapy, castration or female estrogen
Whitmore 1970 Popularized retropubic iodine 125 brachytherapy
John E. McNeal 1972 Reported 4 prostatic zones; described pre-prostatic sphincter
S. Furuya et al. 1982 Suggested that almost 50% of prostatic obstruction is attributed to neural pathways on smooth muscle of bladder neck, and preprostatic and prostatic smooth muscle
Patrick C. Walsh 1982 Advocated identification and preservation of neurovascular bundle to avoid impotence after radical prostatectomy
Schuessler et al. 1991 Described laparoscopic pelvic lymphadenectomy
Onik & Cohen 1993 Popularized transperineal cryoablation for prostate cancer

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Prostate Table

Chapple CR. Anatomy and innervation of the prostate gland. In: Chapple CR (ed). Prostatic Obstruction: Pathogenesis and Treatment. New York: Springer-Verlag, 1994.

Hæger K. The Illustrated History of Surgery. London: Harold Starke, 1989.

Schuessler WW, Vancaillie TG, Reich H, Griffith DP. Transperitoneal endosurgical lymphadenectomy in patients with localized prostate cancer. J Urol 1991;145:988-991.

Walsh PC, Retik AB, Vaughn ED, Wein AJ (eds). Campbell’s Urology, 7th Ed. Philadelphia: WB Saunders, 1998.

Bulbourethral Glands (of Cowper) 
William Cowper 1699 Described the bulbourethral glands. Usually referred to also as their discoverer. However, in spite of the fact that the glands are often called “Cowper’s glands,” they were really discovered by Jean Méry (1645-1722). Today their function is still obscure.

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Bulbourethral Glands Table

Persaud TVN. A History of Anatomy: The Post-Vesalian Era. Springfield, IL: Charles C. Thomas, 1997, p. 245.

Male Urethra 
Egyptians 3000-2000 BC Used sounds or similar devices to dilate strictures
Celsus ca. 400 BC Described urethrotomy for impacted urethral calculus
Heliodorus & Antyllus ca. AD 150 First to attempt hypospadias repair
Ferri 1530 Described first use of cutting sound
Bell 1816 Described external urethrotomy and placement of catheter to treat strictures. Also described excision of diseased segment, followed by catheter placement.
Civiale & Guillion 1831 Introduced blind urethrotomy with retractable blades
Dieffenbach 1838 Treated hypospadias by piercing glans to allow cannula to remain in position until channel became lined with epithelium
Mettauer 1842 Suggested multiple subcutaneous incisions to straighten chordee
Boisson 1861 Suggested transverse incision at point of greatest curvature of chordee. Also used scrotal tissue to reconstruct urethra during hypospadias repair. Performed first buttonhole flap.
Thiersch 1869 Used local tissue flaps to repair epispadias
Duplay 1874 Performed staged urethroplasty using central flap which is tubularized and covered by lateral penile skin flaps (later popularized by Browne in 1953, and Horton in 1973)
Otis 1876 Popularized internal urethrotomy with retractable blades
Rosenberger & Landerer 1891 Independently described burying penis in scrotum to obtain skin coverage for later hypospadias repair (later popularized by Cecil-Culp in 1951)
Hook 1896 Described vascularized preputial flap for urethroplasty (later popularized by Davis in 1950, and Broadbent in 1961)
Beck & Hacker 1897 Undermined and advanced urethra onto glans for subcoronal hypospadias repair (later popularized by Waterhouse in 1981)
Beck 1897 Used adjacent rotation flaps from scrotum for resurfacing after Duplay-type urethroplasty (later popularized by Turner-Warwick in 1979)
Nove-Josserand 1897 Used split-thickness skin grafts for hypospadias repair
Russell 1900 Described first one-stage hypospadias repair using urethral tube constructed from flap developed on ventrum of penis. Neourethra was passed through tunnel in glans and secured to tip of glans.
Edmunds 1913 First to transfer skin of prepuce to ventral surface of penis at time of chordee release (later popularized by Byars in 1955)
Bevan 1917 Used urethral meatus-based flap channeled through glans for distal hypospadias repair (later popularized by Mustarde in 1965)
Humby 1941 Described one-stage hypospadias repair using free full-thickness graft from groin or arm
Memmelaar 1947 Described one-stage urethroplasty using bladder mucosa as free graft
Berry 1961 First implant of acrylic prosthesis between bulbous urethra and bulbospongiosus muscle for treatment of incontinence
Hodgson 1970-1972 Described three procedures using vascularized preputial or penile skin grafts for one-stage hypospadias repair
Sachse 1972 Developed endoscopic internal urethrotomy using “cold knife”
Scott, Bradley & Timm 1973 Introduced artificial urinary sphincter
Duckett 1980 Described technique for transverse preputial island flap
Duckett 1981 Described meatal advancement and glanuloplasty incorporated procedure (MAGPI)

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Male Urethra Table

Walsh PC, Retik AB, Vaughn ED, Wein AJ (eds). Campbell’s Urology, 7th Ed. Philadelphia: WB Saunders, 1998.

Penis 
Egyptians, Amorites, Hittites 3000-2000 BC Described circumcision
Bible ? When Abraham made his covenant with God, he was told: “an uncircumcised male who does not circumcise the flesh of his foreskin shall be cut off from his kin.” (Genesis 17:11)
Celsus ca. 400 BC Advocated surgical removal of presumed cancerous lesion of penis leaving margin of healthy tissue
Morgagni 1761 Mentioned procedure of partial penectomy, which was performed earlier by Valsalva
Thiersch 1875 First detailed description of penectomy for penile cancer
MacCormack 1886 Advocated total penile amputation with bilateral inguinal lymphadenectomy for penile cancer
Bogoras 1936 First surgically successful restoration of potency using rib cartilage implanted into a tube skin graft
Mohs 1936 Started use of micrographic surgery for penile cancer
Goodwin & Scott 1952 Used acrylic splints as penile implants for impotence
Beheri 1966 Reported over 700 successful penile implants for impotence
Small & Carrion 1973 Introduced first silicone semi-rigid prosthesis for impotence
Scott, Bradley & Timm 1973 Introduced first inflatable prosthesis for impotence
Cabanas 1977 Introduced concept of sentinel lymph node biopsy for penile cancer

History table compiled by David A. McClusky III and John E. Skandalakis.

References for Penis Table

Walsh PC, Retik AB, Vaughn ED, Wein AJ (eds). Campbell’s Urology, 7th Ed. Philadelphia: WB Saunders, 1998.

Embryogenesis

Normal Development

Gonadal Genesis

Although the gender of an individual is normally determined at conception by the sex chromosomes, the developing gonad shows no morphologic sex differentiation until the seventh to eighth week (indifferent stage). The gonads develop near the kidney in the retroperitoneal space at the lumbar area.

Formation of the gonad is dependent upon three primordia:

 

Primordial germ cells

Genital ridge. The genital ridge is formed by the mesenchyme of the ventromedial aspects of the mesonephros close to the root of the mesentery

Coelomic epithelium overlying the mesenchyme

The arrival of primitive germ cells from the yolk sac is almost completed around the end of the sixth week. At the end of the seventh week or early in the eighth week, the differentiation stage takes place, perhaps with hormonal influence. During this period the testes are suspended by the mesorchium, a double peritoneal fold. The lower fold forms the hunterian gubernaculum. The upper fold transmits the spermatic vessels.

Gubernaculum

The testicular gubernaculum is a gelatinous cylinder of mesenchymal origin. We agree with O’Rahilly and Müller2 on several points concerning the gubernaculum.

 

It does not pull the testis into the scrotum

It does not possess the so-called “tails”

Its increase in size prior to descent is an important factor in the passage of the testis through the inguinal canal

Perhaps Arey3 was correct in stating that the destiny of the gubernaculum is to prepare the way and to provide the space for the testicular journey.

The proximal part of the gubernaculum is attached to the lower pole of the testicle. The organ reaches the scrotum but occasionally passes to the perineum, the pubopenile area, or the femoral area. These areas are the ectopic locations outside the line of physiologic descent. Cryptorchidism results when the descent of the testis is arrested along the normal course (abdominal, inguinal, or prepubic).

We quote Favorito et al.4:

In fetuses without congenital malformations or epididymal alterations, such as tail disjunction or elongated epididymis, the proximal portion of the gubernaculum was attached to the testis and epididymis in all cases. In undescended testes there was an increased incidence of paratesticular structure malformations accompanied by gubernacular attachment anomalies compared to the testes in normal fetuses.

Fascia

The coverings of the spermatic cord are formed by the evagination of the layers of the abdominal wall. The external spermatic fascia is formed by the fascia of the external oblique muscle, not the aponeurosis. The cremasteric fascia is formed by the internal oblique and transversus abdominis muscles. The internal spermatic fascia is formed by the transversalis fascia.

Female Homologues

The proper ligament of the ovary and the round ligament of the uterus are the remnants of the gubernaculum in the female. To be more specific, the ovarian gubernaculum forms the ovarian ligament between the uterus and the ovary and the round ligament extending between the uterus and the labia majora. The round ligament of the uterus passes downward through the inguinal canal and into the labium majus. It is the homologue of the gubernaculum of the undescended testis, not of the spermatic cord of the descended testis. For all practical purposes, the gubernaculum disappears in the male.

Descent of the Gonads

The testis that has not begun its descent is, together with the epididymis, attached to the posterior abdominal wall by a mesorchium that contains the blood vessels and the ductus deferens. It may lie at the level of the lower pole of the kidney, the iliac fossa, or in the pelvis (Fig. 25-1).

Fig. 25-1.

Descent of testis. A, Fifth week. Testis begins its primary descent; kidney ascends. B, Eighth to ninth weeks. Kidney reaches adult position. C, Seventh month. Testis at internal inguinal ring; gubernaculum (in inguinal fold) thickens and shortens. D, Postnatal life. Testis in scrotum; processus vaginalis closed, and gubernaculum (vestigial). (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

The downward journey commences at approximately the third month of gestation. The pathway is retroperitoneal.

During the seventh month the testes are found at the level of the anterior superior iliac spine. The epididymis is in a posterolateral location. The gubernaculum, whose circumference is as large as the testis and the epididymis, is approximately 1.8 cm long. The peritoneum dips into the inguinal canal ahead of the testes, but extends down the gubernaculum only part way. The testes and gubernaculum extend into the canal. The scrotum and the gubernaculum are not attached to each other. The “scrotal ligament” of Lockwood5 fails to qualify as a ligament.

The testes begin to enter the internal ring as the gubernaculum emerges from the external ring. As the gubernaculum reaches the bottom of the scrotal sac, it begins to shorten until its lower two-thirds has disappeared completely. At about the end of the seventh month, the testes pass through the inguinal canal. Although descent through the canal is accomplished in a few days, it takes four additional weeks for the testes to pass from the external ring to the bottom of the scrotum. The best description of testicular descent is that of Scorer.6

Descent may be complete early or may still be incomplete at birth. Among the premature births studied by Scorer,6 the testes were undescended in 50% or more of the larger infants. After the testes emerge through the external ring, the ring contracts.

For a discussion of current theories of the role of androgen in testicular descent, the interested reader is referred to Barthold et al.7

Processus Vaginalis

The proximal part of the processus vaginalis (from the peritoneal cavity to the testis) closes after descent is complete. Closure is complete by birth in 50% to 75% of infants. Scorer believed that this closure may be recognized by palpating the spermatic cord shortly after birth.8

Once the testes are in the scrotum, the distal part of the processus vaginalis forms the tunica vaginalis; the proximal part is usually obliterated. It is unknown, however, why the processus vaginalis closes. Further, it may persist throughout life. The two points of obliteration are the deep inguinal ring and just above the upper pole of the testis.

After the testicular descent, the lumen of the processus vaginalis becomes obliterated above the testis. In the adult, a fibrous band marks the upper (funicular) part of the processus, while the scrotal portion (tunica vaginalis) remains as an isolated peritoneal cavity. A homologous cavity in the female (canal of Nuck) is usually obliterated before birth.

How can we explain the descent of the testicles? Only the good Lord knows, we tell our students. We can mention, however, the influence of hormones and the gubernaculum upon the descent of the testicles. The gubernaculum is immature mesenchymal tissue, which most likely with the aid of the processus vaginalis helps the gonads travel downward by evagination of the lower abdominal wall.

Hormonal Influence

Shapiro,9 in 1930, demonstrated the role of hormones in the descent. Engle10 later induced premature descent of the testes in the macaque with anterior pituitary hormone. Martins11 controlled the descent of paraffin masses simulating the testes in rats and monkeys injected with testosterone. Wislocki12 suggested that maternal chorionic gonadotropin stimulates androgen production in the adrenal cortex of the male fetus, which leads to normal descent. Although ordinary cryptorchidism often demonstrates normal, not low, androgen production, the high frequency of retained testes in various types of pseudohermaphrodites strongly suggests that androgen is an important factor in descent.

The prostate gland, the seminal vesicles, and the ductus deferens develop normally if the Y chromosome is present. If the fetal testicle secretes the müllerian inhibiting substance (MIS), then a regression of the female genital tract occurs. The Leydig cells produce testosterone, which is responsible for the differentiation of the wolffian system. Chorionic gonadotropin is used successfully for the treatment of bilateral undescended testes. However, surgery is the treatment of choice if that therapy is unsuccessful.

Hutson and Baker13 hypothesize that in patients with persistent müllerian duct syndrome (PMDS), the gubernaculum fails to develop during the first phase of descent. They consider the possible role of MIS in initiating this first step, and await more experiments to evaluate its relevance. The etiology of PMDS implicates a role for müllerian inhibiting substance in gubernacular development.

Gubernaculum and Descent

Hutson et al.14 theorize that failure of masculinization of the development of the gubernaculum testes in persistent müllerian duct syndrome allows testicular herniation and perhaps plays a role in testicular descent. Androgens may direct gubernacular migration via release of a second messenger (a calcitonin gene-related peptide) from the genitofemoral nerve.

Although hormones probably regulate descent, the actual mechanics can only be conjectured. If a testis and a gubernaculum together form a cylindrical plug in the inguinal canal, this plug will be forced downward at each rise of pressure in the abdomen, such as from uterine pressure in prenatal life or from crying or straining in postnatal life. If the lower end of the gubernaculum is progressively destroyed, perhaps by hormonal action, the gubernaculum may serve to lower the testes slowly into the scrotum under the pressure of the abdomen. It thereby acts as a brake rather than as a positive traction force, as was originally proposed.

From their studies on the gubernaculum of the pig, Backhouse and Butler15 believe that final descent results from invasion of the remaining gubernaculum by the growing epididymis. We concur with this conclusion.

In several recent publications, Hutson and co-workers16-20 consider various concepts about testicular descent. We present verbatim their summary of these theories21:

The most plausible explanations for testicular descent in the human fetus are related to development of the gubernaculum, processus vaginalis, inguinal canal, spermatic vessels and scrotum since these structures differ substantially between male and female fetuses. The gubernaculum consists of primitive mesenchymal tissue around which the abdominal wall muscles differentiate, creating the inguinal canal. In the early fetus the gubernaculum serves to anchor the testis to the internal inguinal ring. Rapid growth of the gubernaculum before descent may dilate the inguinal canal and rings sufficiently to admit the testis.

Growth of the processus vaginalis toward the tip of the gubernaculum provides a mechanism by which intra-abdominal pressure transmitted via the open processus can exert traction on the gubernaculum and, thereby, on the testis. However, this process of traction is not continuous since the length of the intra-abdominal gubernaculum increases significantly and the testis is freely mobile before inguinal descent, which is relatively rapid. It appears likely that growth of the gubernaculum and processus vaginalis must reach a critical stage before intra-abdominal pressure transmitted via the open processus can effect the rapid inguinal transit of the testis, which is possibly precipitated by fetal respiratory efforts or hiccuping.

Clearly, firm attachment of the gubernaculum to the testis, and adequate lengthening of the spermatic vessels and vas deferens as well as development of the scrotum are also indispensable for full descent. The absence of a firm scrotal attachment of the gubernaculum has discredited the traction theories but it is possible that intra-abdominal pressure exerted via the open processus vaginalis may stabilize the gubernacular tip, and so contraction of the gubernaculum can pull the testis down. The contractility demonstrated in the rodent gubernaculum should be investigated in large mammals since it remains unresolved whether the gubernaculum in these species may be capable of contraction, causing the rapid inguinal passage of the testis.

Although gonadotropins and androgens appear to have a role, their target structures and mechanisms of action remain undefined. It is generally accepted that the fetal spermatic vessels, vas deferens and scrotum are androgen target structures, but this hypothesis has not been biochemically proved in regard to the spermatic vessels. It appears unlikely that androgens are responsible for growth of the gubernaculum but regression of this structure may be androgen-dependent. The theory that androgens exert their effect on the gubernaculum via the spinal nucleus of the genitofemoral nerve and a “second messenger,” such as calcitonin gene-related peptide, needs to be investigated in a nonrodent animal model. In addition, the possibility that growth of the gubernaculum is stimulated by a nonandrogenic fetal testicular hormone different from müllerian inhibiting substance should be further investigated. We hope that the controversy on the enigma of testicular descent will eventually be resolved as speculation gives way to scientifically proved fact.

Role of Temperature

The testicle is sensitive to the warm temperature of the abdominal cavity. Normal body temperature, abnormal for the undescended testicle, arrests spermatogenesis and enables only the Sertoli cells to survive. Spermatogenesis requires a cool climate, as provided in the scrotum. Moore22 proved this when he insulated the scrotum of a ram with a tea cozy. After 80 days, no spermatozoa were found. The ram regained spermatogenesis when the insulating material was removed. Pituitary gonadotropin plays a significant role in these changes, as proven by its importance as a stimulus during puberty.

Much more work is needed to further our understanding of testicular descent. Though we do not understand the intricacies of testicular descent, we know it occurs so the organ can locate itself in a cooler environment. The testicle does not like the warmth of the retroperitoneal space; it is a warrior and does not want to have a fireplace chat with other retroperitoneal fellows. Instead, fighting, constantly alone, the testicle practically destroys the lower abdominal wall. It gloriously seeks out the bracing climate of the scrotum for its abode. This location helps prevent malignancies. It permits the testicle to fulfill its physiologic destiny of successfully producing spermatozoa.

Physicians must not forget the anxieties of young boys suspecting that they have an empty scrotum.

Female Homologues

In females, ovarian descent normally ceases after the 12th week at the area of the pelvic brim. By definition, the canal of Nuck extends into the labium majus in the female; it corresponds to the processus vaginalis of the male. If the processus vaginalis is not obliterated by the 8th prenatal month, a hydrocele may be formed; perhaps an ectopic ovary may be found within the canal of Nuck, in the form of a congenital indirect inguinal hernia.

Congenital Anomalies

Anomalies of the male reproductive tract may be appreciated in Table 25-2 and Fig. 25-2. Anomalies of the gonads are considered below.

Table 25-2. Anomalies of the Male Reproductive Tract

Anomaly Prenatal Age at Onset First Appearance (or Other Diagnostic Clues) Sex Chiefly Affecteda 
 
Relative Frequency Remarks
Müllerian and mesonephric remnants in the male:          
  Torsion of the appendix testis or appendix epididymis   In adolescence Male Uncommon Predisposing factors not known
  Cysts of the prostate utricle 12th week In adulthood Male Uncommon (clinically significant)  
Absence of wolffian derivatives in the male:          
  Complete absence 4th week At birth Male Rare Associated with absence of kidneys and uterus: lethal if bilateral
  Partial absence After the 4th week In adulthood Male Uncommon Bilateral absence casues infertility; unilateral absence is asymptomatic
Duplications of the ductus deferens Late 4th week None Male Rare  
Absence of the seminal vesicle 3rd month or earlier Adulthood only if bilateral Male Unknown Sterility if bilateral
Duplication of the seminal vesicle 3rd month Never Male Unknown Asymptomatic
Anomalies of the prostate gland:          
  Absence of the prostate 12th week In adulthood Male Rare Associated with infantile genitalia and pituitary insufficiency
  Other anomalies ? At any age Male Rare May produce urethral obstruction
Agenesis of the penis 4th week At birth Male Very rare  
Agenesis of the glans penis 4th month At birth Male Very rare  
Defects of the corpus spongiosum and corpora cavernosa 3rd month? At birth Male Very rare  
Duplication of the penis Various times At birth Male Very rare Similar duplication of the clitoris is even rarer
Transposition of the penis and scrotum 9th week At birth Male Very rare  
Duplications of the penile urethra 10th to 14th weeks At any age Male Uncommon  
Atresia and stenosis of the urethra ? In infancy Male Common Present in females also
Hypospadias 8th week or later At birth Male Rare Very rare in females; familial tendency suggested

aThese conditions may occur also in females with anomalous male organs.

Source: Skandalakis JE, Gray SW, eds. Embryology for Surgeons, 2nd Ed. Baltimore: Williams & Wilkins, 1994; with permission.

Fig. 25-2.

Sites of developmental anomalies of male reproductive tract. (Modified from Skandalakis JE, Gray SW. Embryology for Surgeons (2nd ed). Baltimore: Williams & Wilkins, 1994; with permission.)

Undescended Testis

The proportion of undescended testes increases with prematurity of the neonate. Scorer23 found undescended (cryptorchid) testes in 21 percent of premature neonates and in only 2.7 percent of full term neonates. By the end of the first year of life, testes were undescended in only 0.8 percent. Retraction of the testis by the cremaster muscle in young boys (cremasteric reflex) may produce a false diagnosis of undescended testis.24

An undescended testis may remain in the abdomen, or its descent may be arrested in any portion of the normal pathway from the abdomen to the scrotum (Fig. 25-3A). The most common site of arrest (62 percent) is the inguinal canal. Figure 25-3B shows the proportion of testes arrested at various locations.

Fig. 25-3.

A, Ectopic testes. Perineal ectopia not shown. B, Undescended testes. Percentages of testes arrested at different stages of normal descent. (Data from Campbell MF, Harrison JH. Urology (3rd ed). Philadelphia: Saunders, 1970. Modified from Skandalakis JE, Gray SW. Embryology for Surgeons (2nd ed). Baltimore: Williams & Wilkins, 1994; with permission.)

Among premature infants, failure of descent is usually bilateral; among infants of normal birth weight, the right testis is much more often undescended than is the left. In adults, this proportion is reversed.

An undescended (cryptorchid) testis may or may not be normal. If it is brought down surgically before 2 years of age, a normal testis may become functional. If it is not brought down until puberty, it will almost surely be nonfunctional. Remember that surgical correction of the undescended testis always involves repair of an indirect inguinal hernia.

Histologic Changes

Even though at birth the volume of undescended testis is relatively normal, it decreases as time passes. Testicular histologic abnormalities accounting for this phenomenon can be summarized as a progressive deterioration of the number of germ cells. This change can be noted as early as the second year of life. It is common to find a total lack of germ cells in orchiectomy specimens of cryptorchid teenagers who have not been previously treated. Further, more proximal testes (e.g., abdominal) are more severely affected.25

How histologic abnormalities relate to adult infertility in previously cryptorchid patients is not entirely clear. Several retrospective studies have not clearly defined a corelation between paternity and age at orchiopexy.26,27 Despite a lack of good data, most surgeons prefer to offer correction before evidence of histologic abnormalities can be shown. Orchiopexy prior to age 2 is currently the accepted norm. It has been shown that early orchiopexy (age 1-2) correlates with improved fertility.28

Malignancy

There is definitely an increased incidence of malignancy in cryptorchid testes. It appears that an undescended testis is thirty-five times more likely to be found in those with testicular tumors than in the general male population.29 A calculation of the incidence of malignancy in cryptorchid patients, as contrasted with the increased presence of cryptorchid individuals in malignancy cases, is more difficult to ascertain and requires certain statistical assumptions.30 It has been estimated to be 48.91 per 100,000. This represents a 22-fold increase over the rate of 2.2 per 100,000 in adults who experienced the development of tumors in normally descended testes. In Martin’s29 earlier report, all patients with tumors had orchiopexy performed after 5 years of age. However, there currently are reports of tumors developing when surgery is performed earlier. Testicular seminoma which developed 14 years after orchiopexy for undescended testis in a patient with Noonan’s syndrome was reported by Aggarwal et al.31 Long-term follow-up of patients undergoing orchiopexy at any age seems advisable.

Defects of Closure of the Processus Vaginalis

Defects of closure of the processus vaginalis are not unusual. They may be classified as diverticular defects and cystic defects.

A patent processus vaginalis may be unilateral or bilateral. Routine inguinal herniography to identify cryptorchidism patients with a patent processus vaginalis, for whom nonsurgical treatment would be ineffective, was urged by Varela-Cives et al.32 Owings and Georgeson33 report that laparoscopic exploration of a symptomatic unilateral inguinal hernia to detect a contralateral patent processus vaginalis is safe and accurate.

Diverticular Defects

There are three types of diverticular defects:

 

Congenital indirect hernia

Acquired indirect inguinal hernia

Sliding indirect hernia

Congenital Indirect Hernia

A completely open processus vaginalis occurs in congenital indirect hernia (Fig. 25-4A). Herniation of intestine or omentum occurs at or shortly after birth.

Fig. 25-4.

Defects of closure of processus vaginalis. In A, B, and F right half of diagram is cross section of area indicated by connecting diagonal line. X, processus vaginalis. A, Completely unclosed processus. An intestinal loop or omentum may follow testis into scrotum (congenital indirect hernia). B, Cranial (funicular) portion of processus unclosed. Herniation may occur later in life (acquired indirect hernia). C, All but cranial portion unclosed. Serous fluid accumulates to form infantile hydrocele. D, Midportion of processus unclosed, forming cyst (cystic hydrocele). E, Normally closed processus. Fluid may accumulate in tunica vaginalis (adult hydrocele). F, Sliding indirect inguinal hernia. Descending viscus, usually colon, remains retroperitoneal. Sac (processus vaginalis) remains unclosed or becomes closed. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Acquired Indirect Inguinal Hernia

In this condition an unclosed cranial (funicular) portion of the processus opens into the peritoneal cavity (Fig. 25-4B). The lower portion of the processus is closed. Acquired indirect inguinal hernia increases the possibility of herniation later in life.

Sliding Indirect Hernia

A sliding indirect hernia forms when a “retroperitoneal” viscus, usually the cecum or the sigmoid colon, descends behind, rather than within, an open processus vaginalis (Fig. 25-4F). The descending viscus forms the posterior wall of the empty processus. Efforts to mobilize the posterior wall of the sac will jeopardize the blood supply to the viscus. The sac must be opened anteriorly, but is not to be dissected from the spermatic cord.

Cystic Defects

When the processus is closed at the cranial end only, an accumulation of fluid can produce hydrocele (Fig. 25-4C). An infantile hydrocele may have a patent processus vaginalis (communicating hydrocele).

If the midportion of the processus is unclosed, it leaves a closed cyst (Fig. 25-4D). This forms a cystic or funicular hydrocele or a hydrocele of the spermatic cord.

NOTE: Collection of fluid in a normally developed tunica vaginalis produces adult hydrocele (Fig. 25-4E).

Ectopic Testis

By definition, ectopic testes are outside the path of normal descent. If the testis is not in the scrotum or in the normal path of descent, it may be ectopic. When both testes migrate toward the same hemiscrotum, a symptomatic inguinal hernia may occur on the side of the migration.34 Ectopic testes are baffling and, fortunately, very rare. Figure 25-3A shows some of the sites in which ectopic testes have been found.

The term cryptorchidism covers both undescended and ectopic (maldescended) testes. Both should be located and placed in the scrotum at an early age if at all possible. If surgery is performed on an adult, orchiectomy should be considered.

We quote Hutcheson et al.35:

Similar pathological findings in ectopic and undescended testes as well as the association of ectopic testis with a contralateral undescended testis suggest that ectopic and undescended testes are variants of the same congenital anomaly. Thus, boys with ectopic testis may have an increased incidence of subfertility and testicular malignancy. This spectrum of abnormal testicular position, and its range of pathological conditions and complications may appropriately be called the undescended testis sequence.

Appendix Testis and Appendix Epididymis

The ductus epididymis arises from the mesonephric (wolffian) duct as does the ductus deferens. The ductuli efferentes drain the rete testes; as they leave the tunica albuginea on their way to open into the epididymis they beome highly convoluted so that each ductule forms a lobule at the head of the epididymis.

Superior aberrant ductules remain connected with the testis but not with the epididymis. They are reported to be the source of spermatoceles. Inferior aberrant ductules (aberrant vas of Haller) lose their connection with the testis but retain connections with the epididymis. They apparently are known to undergo torsion with varying levels of discomfort as the result.

The paradidymis (organ of Giraldes) comprises persistent remnants of mesonephric tubules which are connected to neither the epididymis nor the testis. No symptoms are attributed to this structure. The cranial part of the mesonephric duct becomes the appendix of the epididymis (hydatid of Morgagni).36 It is a pedunculated structure which may undergo torsion. This produces aching that ranges in intensity from dull to marked and requires surgical intervention. Finally, the appendix of the testis is the remnant of the cranial end of the paramesonephric (müllerian) duct. It, too, may undergo torsion and cause severe discomfort to the patient.

Surgical Anatomy

Topography and Relations

Testis

The normally descended testis is ovoid and about 4 cm in length. The tunica vaginalis of peritoneum envelops the whole testis except its posterior border and its superior pole.

The testis itself is surrounded by a dense, irregular connective-tissue capsule, the tunica albuginea. Posteriorly, the tunica forms a median septum, the mediastinum testis, from which more delicate connective tissue divides the parenchyma into 200 to 300 compartments that contain the seminiferous tubules. These coiled tubules anastomose in the mediastinum of testis to form the rete testis, from which 6 to 12 ductuli efferentia pass to the head of the epididymis.

The testis has two free surfaces, the medial and the lateral, and two borders, the anterior and the posterior. The posterior border has a superior portion that is related to the head of the epididymis, and an inferior portion that is related to the body and tail of the epididymis.

The right testicle, in most cases, is at a higher level than the left. Occasionally, the right testicle is lower in total situs inversus, and, according to Chang et al.,37 in left-handed men. For medicolegal reasons, this finding should be reported in the patient’s chart.

Epididymis

The head of the epididymis is firmly fixed to the upper pole of the testis (Fig. 25-5). The body and the tail are less firmly fixed to the posterior border of the testis. This posterior surface is not covered by the tunica vaginalis, but it is the site of the blood and nerve supply to both organs.

Fig. 25-5.

Epididymectomy. A, An epididymal branch of testicular artery supplies epididymis. B, Epididymis dissected from below. Branch of testicular artery to testis must be preserved. Branch to epididymis (reflected upward) may be ligated at X. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

At the upper one-third of the posterior border, the testicular artery bifurcates into testicular and epididymal branches (Fig. 25-5). During epididymectomy, the surgeon should start from the lower pole and proceed upward about 2.5 cm. This will avoid injury to the testicular branch of the artery and testicular atrophy.

The surgeon should remember that the epididymis may not be in its normal position (Fig. 25-6A). It may be elongated (Fig. 25-6B) or dissociated from the testis (Fig. 25-6B through E). There may be a very small tunica vaginalis, or it may be wider than usual, forming a mesorchium (Fig. 25-6C).

Fig. 25-6.

Varieties of separation of testis and epididymis. A, Normal relations. B, C, D, E, One or both structures maldescended E, Epididymis normally descended: testis remains above internal ring. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Occasionally, the epididymis is descended and the testis is retained (Fig. 25-6E). Such separation of testis and epididymis usually results in blindly ending vasa efferentia dilated to form spermatoceles. The testis itself may or may not be normal. If the condition is bilateral, the patient will be sterile.38

Spermatic Cord

The spermatic cord is a matrix of connective tissue continuous proximally with the preperitoneal connective tissue. Concentrically invested by three layers of tissue, the cord contains the ductus deferens (vas), three arteries, three veins, the pampiniform plexus, and two nerves. One other nerve, the ilioinguinal, lies just lateral to the major layers of the cord.

The elements of the spermatic cord relate to each other as follows.

 

Anterior: pampiniform plexus

Posterior: ductus and remnant of processes vaginalis or hernial sac

These anatomic entities of the spermatic cord, as well as others, are covered by the spermatic fasciae. The spermatic cord on its way to the scrotum may be found deep under the fasciae of Scarpa and Colles.

The components of the spermatic cord are listed in Table 25-3. The key to remember is “three”: three layers of fasciae, three arteries, three veins, three nerves, multiple lymphatics, and one ductus.

Table 25-3. The Spermatic Cord and Its Covering

Three fasciae:
  External spermatic (from external oblique fascia)
  Cremasteric (from internal oblique muscle and fascia)
  Internal spermatic (from transversalis fascia)
Three arteries:
  Testicular artery
  Cremasteric artery
  Deferential artery
Three veins:
  Pampiniform plexus and testicular vein
  Cremasteric vein
  Deferential vein
Three nerves:
  Genital branch of genitofemoral nerve
  Ilioinguinal nerve
  Sympathetic nerves (testicular plexus)
Lymphatics

Source: Skandalakis JE, Colborn GL, Pemberton B, Skandalakis LJ, Gray SW. The surgical anatomy of the inguinal area. Part 2. Contemp Surg 38:28-38, 1991; with permission.

Fasciae

The ductus deferens and the accompanying blood vessels of the spermatic cord are surrounded by three layers of fascia.

 

External spermatic fascia, the outermost layer, is a continuation of the fascia of the external oblique muscle.

Cremasteric fascia is primarily continuous with the musculature and fascia of the internal oblique and, in some cases, the transversus abdominis muscle as well.

Internal spermatic fascia is a continuation of the transversalis fascia.

Stoppa et al.39 discuss the retroparietal spermatic sheath and present the posterior relations of the spermatic sheath of the spermatic cord to the external iliac vessels. They advise preservation of this part of the spermatic sheath when spermatic cord mobilization occurs during hernia repair. Preservation avoids perivascular sclerosis due to contact with a large prosthesis.

Vascular Supply

Arteries

The arteries of the testis and the epididymis are shown in Figures 25-7 and 25-8. The internal spermatic, or testicular, artery arises from the aorta. Shinohara et al.40 reported a variation in which the left testicular artery originated from the aorta 1 cm above the origin of the left inferior phrenic artery. The testicular artery is the chief source of blood to the testis. The artery of the ductus deferens (deferential artery) emerges from the inferior vesicular artery. The external spermatic, or cremasteric, artery springs from the inferior epigastric artery.

Fig. 25-7.

Arterial supply of testis and epididymis. 1, Testicular artery. 2, Deferential artery. 3, Cremasteric artery. 4, Posterior scrotal artery. 5, Anterior scrotal artery. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Fig. 25-8.

Internal arterial distribution of the testis and epididymis. (From Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993; with permission.)

Four other arteries anastomose with the testicular artery and each other to form a collateral circulation.41 There are anastomoses between the testicular and deferential vessels (fig. 25-7). A good anastomosis exists between the gonadal and the deferential arteries in all patients. There are also some anastomoses between these and the cremasteric arteries in approximately two-thirds of patients. Additional anastomoses appear to exist between the testicular, cremasteric, and scrotal vessels.

According to Neuhof and Mencher,42 collateral circulation is sufficient to prevent gangrene upon division of the cord in 98% of their patients. Testicular atrophy occurred in 19 of the 24 patients. Among a larger group, Burdick and Higinbotham43 found atrophy in 80% and gangrene in 2 percent.

If the cord is divided, it is advisable to keep the testicle in the scrotum and not bring it into the surgical field. Collateral circulation will probably be better served with this action.

Bifurcation of the testicular artery into the main testicular and epididymal branches occurs between the upper and middle one-third of the testicle. Dissection of the epididymis during epididymectomy should start at the lower pole of the testicle and proceed upward (approximately 2.5 cm). From there, the surgeon will find the bifurcation, and should ligate only the epididymal branch.

Veins

According to Hinman,44 the veins that drain the testis, epididymis, and spermatic cord connect with a deep and a superficial venous network. The deep network is the more common pathway and has three components:

 

Anterior: Pampiniform plexus and testicular vein

Middle: Deferential and funicular veins

Posterior: Cremasteric veins

The pampiniform venous plexus is formed in the spermatic cord by 10 to 12 veins that segregate into anterior and posterior groups (Fig. 25-9). Each group is drained by three or four veins that join to form two veins proximal to the internal inguinal ring. These veins run in the extraperitoneal space on either side of the testicular artery. The vein on the right opens into the inferior vena cava; that on the left enters the left renal vein. The cremasteric venous network flows into the inferior epigastric veins. The deferential vein drains into the pelvic plexus.

Fig. 25-9.

Deep and superficial venous networks of testis, epididymis, and ductus deferens (vas). (A.), Anterior pathway. (M.), Middle pathway. (P.), Posterior pathway. (Modified from Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993; with permission.)

The superficial venous network is described as follows by Hinman44:

The scrotal veins drain through the external pudendal veins into the internal saphenous vein or through the superficial perineal veins into the internal pudendal vein. Within this system, the cremasteric vein joins the venous plexus of the spermatic cord and the inferior epigastric vein.

Lechter and coworkers45 dissected 100 cadavers (88 male, 12 female). They produced a beautiful and complete report on the anatomy of the gonadal vessels for both sexes, finding a 20% rate of variance from the typical pattern (Fig. 25-10, Fig. 25-11, Table 25-4, Table 25-5, Table 25-6).

Table 25-4. Gonadal Veins: Age, Length, and Diameter Distribution

  Minimum Maximum Mean SD
Age (yr) 16 76 34.6 14.9
Length (cm) 12 33 23.1 3.7
Diameter (mm) 0.1 0.8 0.31 0.11

Source: Lechter A, Lopez G, Martinez C, Camacho J. Anatomy of the gonadal veins: A reappraisal. Surgery 109:735-739, 1991; with permission.

Table 25-5. Gonadal Veins: Location and Number of Valves

Level/Valvated Veins Right, 48% (%) Left, 62% (%)
Ostial valve 84 77
Upper third 12 13
Middle third 2 3
Lower third 2 7

The left gonadal vein is valvated more often than the right side (p = 0.001). Roughly 80% of valves are located at the ostium.

Source: Lechter A, Lopez G, Martinez C, Camacho J. Anatomy of the gonadal veins: A reappraisal. Surgery 109:735-739, 1991; with permission.

Table 25-6. Gonadal Veins: Collaterals

  Right, 49% Left, 67%
Level/Veins with Collaterals % G/R (%) % G/R (%)
Upper third 26 61/39 42 88/12
Middle third 36 52/48 46 45/55
Lower third 10 0/100 12 0/100

G, Collaterals coming from Gerota’s perirenal fat; R, collaterals coming from retroperitoneal tissues.

The right gonadal vein has fewer collaterals than the left gonadal vein (p = 0.001).

Source: Lechter A, Lopez G, Martinez C, Camacho J. Anatomy of the gonadal veins: A reappraisal. Surgery 109:735-739, 1991; with permission.

Fig. 25-10.

Anatomic variations of terminations. (Modified from Lechter A, Lopez G, Martinez C, Camacho J. Anatomy of the gonadal veins: A reappraisal. Surgery 1991;109:735; with permission.)

Fig. 25-11.

Number of venous trunks. (Modified from Lechter A, Lopez G, Martinez C, Camacho J. Anatomy of the gonadal veins: A reappraisal. Surgery 1991;109:735; with permission.)

Lymphatics

A superficial plexus and a deep plexus of lymph vessels drain the testis and the epididymis upward through the spermatic cord to the lateral and preaortic lymph nodes.

Innervation

The innervation of the testis is effected by sympathetic and general visceral sensory fibers associated with the collateral ganglia and plexuses of the aorta in the region of the superior mesenteric and renal arteries. These fibers course with the testicular arteries to the testes for sympathetic supply and sensory innervation (pain). The spinal cord levels involved in the pain pathway are those from which thoracic splanchnics arise, i.e., T5 to T12 (but chiefly from T10 and T11).

The genital branch of the genitofemoral nerve (L1, L2) enters the inguinal canal through the internal inguinal ring. This branch serves the cremasteric muscle. The ilioinguinal nerve (L1) emerges between the external and internal oblique muscles near the anterior superior iliac spine. It then enters the canal and subsequently exits from the external inguinal ring. There, the ilioinguinal nerve supplies the skin of the penile root, the upper part of the scrotum, and the upper, medial thigh.46-48

The arteries of the cord and the ductus deferens receive their autonomic supply by sympathetic fibers originating from the prostatic portion of the pelvic plexus.

Histology

Testis

The histology of the testis will be briefly described from outside to inside. The tunica vaginalis has two serous layers (parietal and visceral) which represent the outpocketing of the peritoneum. Under the visceral layer, the tunica albuginea is dense connective tissue enveloping the testicular parenchyma; its fibrous septa form approximately 300 pyramid-shaped lobules. The bases of the pyramids are related to the tunica albuginea; the apices are related to the posterior aspect of the tunica albuginea forming the mediastinum testis.

Each pyramidal lobule contains 2-4 convoluted seminiferous tubules which are responsible for the genesis of spermatozoa. Posteriorly, these convoluted tubules become straight and anastomose. They form the rete testis from which 10-12 efferent ducts are formed. The efferent ducts pierce the tunica albuginea and pass into the head of the epididymis.

The interstitial tissue lies between the tubules. It contains the Leydig cells which synthesize testosterone and other steroid hormones. The Sertoli cells lining the lumen of the seminiferous tubules are epithelial cells and have some metabolic effect on the germinal cells.

Each testis contains approximately 500 seminiferous tubules, with a combined length of approximately 250 m.

Epididymis

The epididymis is a long (4-6 m) and very tortuous tube. It is lined by pseudostratified columnar epithelium, which rests on a basement membrane with smooth muscle fibers. These fibers serve, perhaps, to propel the sperm to the ductus deferens.

Spermatic Cord

The histology of the spermatic cord is that of the anatomic entities it contains.

Physiology

Testis

The two testicular functions are spermatogenesis, which is the production of spermatozoa (gametes), and production of the steroid testosterone. After the sperm forms in the testis, it travels via the epididymis, the ductus deferens, and the urethra to be expelled by ejaculation.

Testosterone is responsible for the regulation, maintenance, well-being, and transport of the spermatozoa, as well as for the development of the reproductive glands and secondary sex characteristics.

Malignant testicular tumors are common (most are seminomas). Germ cell tumors are the most commonly diagnosed malignancies in male patients between the ages of 15 and 35.49 Benign tumors are very rare. A palpable abdominal mass in childhood or early adulthood could be a metastasis from painless testicular tumors. Palpate both testes gently and very completely, and order a sonogram if the form of the testis is suspicious. For clinical stage I nonseminoma, retroperitoneal lymph node dissection is advised for staging, prognostic, and therapeutic purposes.50 Nerve sparing retroperitoneal lymphadenectomy, with identification of the postganglionic nerves, results in the preservation of ejaculation in most patients with low-stage disease and in select patients with advanced disease.51

The following summarizes nodal infiltration in metastasis:

 

Right testicle:

 

– to the node or nodes located at the vicinity of the angle between the renal vein and the IVC

– to the precaval nodes at the aortic bifurcation

Left testicle:

 

– to the paraaortic nodes

– to the preaortic nodes (inferior mesenteric nodes)

NOTE: From either testicle, metastasis occasionally reaches into the pelvis and to the external iliac nodes.

Epididymis

The epithelium of the epididymis contains nutrient fluid and hormones. The function of the epididymis is not well understood. Perhaps it helps with the motility of the sperm. With some assistance from the Sertoli cells, the epithelium of the epididymis may assist the maturation of the sperm and influence the sperm’s ability to fertilize the ovum.

Spermatic Cord

The physiology of the spermatic cord is that of the anatomic entities it contains.

Surgical Applications

Varicocelectomy

If the patient is symptomatic, the treatment of choice is ligation of the dilated veins. In adolescent boys with varicocele, some element of testicular growth arrest may be found, such that the testis ipsilateral to the varicocele is often significantly smaller. Current indications for correction in teenage boys are for repair of a large varicocele (particularly if symptomatic), and for a discrepancy in testicular size exceeding 10-20%. Surgical correction has been shown to restore testicular volume in a high percentage of cases. However, Grasso et al.52 found that left spermatic vein ligation for low-grade varicocele in patients more than 30 years old did not improve sperm quality or rate of paternity when compared with an untreated control group.

Salerno et al.53 studied vascular variants in anastomosis between the internal spermatic vein and visceral veins. They stressed the importance of accurate venography with a skilled interventional radiologist prior to sclerotherapy.

Epididymectomy

In epididymectomy, the surgeon must free the epididymis from the testis. Dissect from below upward for about 2.5 cm (1 inch). Visualize the testis as three equal parts, i.e., the upper pole, the central segment, and the lower pole. The bifurcation of the testicular artery is found somewhere between the central segment and the upper pole. Small branches may be ignored, but the epididymal branch must be identified and ligated.

Orchiopexy

An empty scrotal sac implies an undescended or maldescended testis. True agenesis of the testis is extremely rare. The retained testis should be brought down before the child is 2 years old. After the child reaches 10 years, the testis should be removed rather than brought down.

Early orchiopexy is recommended for the following reasons:

 

Cosmetic considerations are important; children can be cruel to those who are “different.”

Preservation of function may be possible if the testis is relocated early enough. However, remember Hunter’s1 dictum that the testis failed to descend because it was defective and was not defective because it failed to descend.

It reduces risk of trauma, especially to ectopic testis.

It reduces risk of malignant changes in the retained testis.

It repairs coexisting indirect inguinal hernia.

Hutcheson et al.54 stated that good knowledge of the retroperitoneal fascial layers is the key to successful inguinal orchiopexy. We quote their anatomical description:

The intermediate stratum of the retroperitoneum consists of the connective tissue between the transversalis fascia, also known as the endoabdominal fascia or outer stratum, and the connective tissue of the peritoneum or inner stratum. Proximally the ureter, spermatic vessels and vas are bound in an investing fascia comprising the intermediate stratum. As the vas joins the vessels, the fibers of the intermediate stratum attenuate and these structures are enveloped by the fascia of the inguinal canal, called the internal spermatic fascia, which is contiguous with the transversalis fascia. This investing fascia holds the hernial sac, vas, vessels and cremasteric fibers together. When the testis stops short of the scrotum in its course of descent, the vas and vessels may not be foreshortened. They may be folded in the retroperitoneum and held in place by this investing fascia, as though they were in a retroperitoneal felt.

Orchiectomy

Every effort should be made to save the testicle except in testicular necrosis due to spermatic torsion or malignancy. The most common testicular malignancy in children is a yolk sac tumor. Removal of the testicle may be approached through the scrotum in benign disease (e.g., hydrocele) or through an inguinal incision if malignancy is suspected (elevation of alpha-fetoprotein). The scrotal approach should be done through a transverse scrotal incision since the blood vessels run transversely.

With testicular malignacy, retroperitoneal lymphadenectomy may be necessary as well as high ligation and removal of the spermatic cord. Occasionally hemiscrotectomy must be done if there is a fixation of the testicle to the skin.

Anatomic Complications

Varicocelectomy

Persistence of varicosities is the most frequent complication. It results from failure to ligate all the varicosed veins. The ductus deferens and its artery, as well as the testicular artery, must be identified and protected. Best results with few complications have been obtained when the testicular artery and vein are ligated above their confluence with the ductus deferens and its accompanying deferential artery.55

Epididymectomy

Every precaution must be taken to preserve the main trunk of the testicular artery (see Fig. 25-5). Injury to this artery will result in testicular atrophy at best and testicular necrosis at worst.

Orchiopexy

The most common complication of orchiopexy is injury to the blood supply from ligation or excessive traction on a “short” spermatic cord. After careful lysis of all adhesions, if the cord is too short to place the testis in the scrotum, the internal ring should be opened. The spermatic vessels must not be sacrificed for an additional length of cord. Hunt et al.56 described a method for increasing the available length of the spermatic cord. Caruso et al.57 advocate a single high scrotal incision for patients with a palpable undescended testicle below the external ring for dissection of the hernial sac and relocation of the testis.

Remember that the collateral blood supply to the normal descended testis is not available to the relocated testis.

Orchiectomy

The primary complications of orchiectomy are bleeding and formation of hematoma (inguinal or scrotal). A vertical incision should never be used because the blood vessels of the scrotal wall run transversely.

Bleeding from the cut edge of the tunica vaginalis can be prevented by wrapping the scrotum with an elastic bandage for 24 hours. Pressure must be uniform and the bandage must be smooth to avoid local skin necrosis.

Ductus Deferens (Vas)

History

The anatomic and surgical history of the ductus deferens is shown in Table 25-1.

Embryogenesis and Congenital Anomalies

The mesonephric ducts are stimulated by testosterone, which is produced by the Leydig cells. The ducts form the right and left ductus deferens.

Congenital anomalies are found in Table 25-2. They include the following malformations.

 

Absence of ductus deferens (unilateral or bilateral)58

Congenital atresia

Duplication

Ectopia

Anomalous pathway

Other possible associated anomalies

Surgical Anatomy

The ductus deferens starts where the epididymal duct (epididymal tail) ends, and terminates at the ejaculatory duct (Fig. 25-12). The ductus has a length of about 45 cm. Characteristically, its tortuous proximal part and almost straight distal part are dilated.

Fig. 25-12.

Seminal vesicles and associated ducts. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Pathway

The pathway of the ductus is scrotal, inguinal, abdominal, and pelvic.

Within the scrotum, the ductus has an ascending course at the medial side of the epididymis and the posterosuperior area of the testicle.

Within the inguinal canal, the ductus is incorporated into the spermatic cord. It is located posteromedially in the cord, and is surrounded by the venous pampiniform plexus.

At the deep inguinal ring (abdominal), the ductus leaves the cord. It proceeds toward and into the pelvis after looping over the inferior epigastric artery and in front of the external iliac artery and vein. In the pelvis, the ductus descends from the pelvic sidewall with its deferential arterial supply, supported by a delicate mesentery.

Relations

The ductus is related to the following anatomic entities during its backward pathway to the base of the bladder (Fig 25-13):

 

lateral to the umbilical artery

lateral to the obturator nerve and vessels

lateral to the superior vesical vessels

anteromedial side of the ureter

posterior aspect of the bladder

medial to the seminal vesicles where it becomes dilated as the ampulla

Fig. 25-13.

Relations and vasculature of prostate, seminal vesicles, and ductus deferens. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

The ductus continues toward the base of the prostate, joining the duct of the seminal vesicle to form the ejaculatory duct. The ejaculatory duct passes anteroinferiorly through the prostate to reach the summit of the seminal colliculus, the expanded portion of the urethral ridge in the prostatic part of the urethra.

Remember

 

The ductus can be palpated in the upper part of the scrotum as a firm cord.

The ductus can also be palpated at the posterior aspect of the spermatic cord during open inguinal herniorrhaphy.

The ductus deferens is located at the lateral side of the inferior epigastric artery, where the elements of the spermatic cord separate just inside and lateral to the internal abdominal ring. At the lower, inner part of the deep inguinal ring, from medial to lateral, are the cremasteric artery, the genital branch of the genitofemoral nerve, and the ductus.

The topographic anatomy and relations of the ductus within the lower abdomen and pelvis should be kept in mind.

Histology and Physiology

The ductus is a long tube with a very thick wall and a very narrow lumen. Its mucosa has the same epithelium as the epididymis, and its thick muscular wall is formed by smooth muscle cells.

A small portion of the sperm is stored in the epididymis, but the majority is stored in the ductus deferens.

Surgical Applications

The general surgeon encounters more and more patients requesting bilateral partial vasectomy as a contraceptive measure to provide elective sterility in men. The incision for vasectomy should be made high on the scrotum, well away from the epididymis. The ductus deferens (vas) can be pulled out for 4 to 6 cm for ligation. Precautions must be taken in this procedure to avoid spontaneous recanalization of the ductus.

In vasectomy, simple ligation is not an adequate procedure. A segment of the ductus should be removed. Some surgeons cauterize both ends of the cut ductus,59 or fold each end over and bury each in a different scrotal layer.60 It has become commonplace, when a patient requests it, to perform vasectomy during laparoscopic or open herniorrhaphy.

Epididymectomy for treatment of scrotal pain following vasectomy was recommended by West et al.61

Anatomic Complications

Vascular Injury

During vasectomy, hemorrhage from the scrotal wall must be avoided. The blood vessels run transversely, so a vertical incision should never be used. Suture the subcutaneous layer with absorbable continuous or interrupted sutures when closing the incision. An elastic bandage will maintain gentle compression for 24 hours.

Inadequate Procedure

Sperm granuloma is the result of leakage of sperm from the proximal cut end of the ductus. It can occur during the operation or later if the stump is inadequately occluded; rupture of an epididymal tubule is a rare but possible cause. The usual cause is from ligatures that cut through the wall of the ductus. The incidence can be as high as 60 percent.62 Schmidt and Morris63 considered sperm granuloma to be the most important complication of vasectomy.

The granuloma may be self-limiting and may respond to conservative treatment, but surgical excision is sometimes required. Pain, over a period of months, is suggestive of sperm granuloma.

Spontaneous restoration of the ductus deferens has been reported in as many as 6 percent of some series.63 This is the result of inadequate ligation. Very rarely, duplication of the ductus is encountered. Usually, but not always, a supernumerary testis is also present.65 A second ligation is required if sperm appear in the ejaculate.

Potential Spaces above the Urogenital Diaphragm

Surgical Anatomy

The fascial layers in the perineum are complicated and unpredictable to some degree. In brief, Camper’s fascia of the anterior abdominal wall (Fig. 25-14) is continuous with the fatty layer in the perineum, thigh, and gluteal region. Scarpa’s membranous layer extends into the perineum, but is referred to there as Colles’ fascia. Further, Camper’s fascia and Scarpa’s fascia of the anterior abdominal wall blend, become thinner and coalesce with smooth muscle fibers to form the dartos tunic of the external genitalia.

Fig. 25-14.

Skin and fascia of inguinal area. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

The fascial layer on the external surface of the external oblique muscle and rectus sheath is called the fascia of Gallaudet (sometimes referred to as the innominate fascia). A similarly-named counterpart is to be found covering the muscles in the superficial compartment of the perineum. This deep fascial layer is called Buck’s fascia on the penis, and forms the deep fascia of the penis.

The seeming simplicity of arrangement of fascial layers, as described above, is belied by variations in degree of lamination of fibrous tissue associated with Camper’s fascia, and its intermingling with Scarpa’s fascia in the lower part of the anterior abdominal wall and perineum. In addition, there may be some adipose tissue between Colles’ fascia and the deep fascia of Gallaudet in the perineum. On the genitalia, the space between superficial fascia and Buck’s fascia is easily determined.

Scrotum

History

The anatomic and surgical history of the scrotum is shown in Table 25-1 under the heading Testes, Epididymis, and Scrotum.

Embryogenesis

Normal Development

The formation of the scrotum is a result of the fusion of the right and left labioscrotal folds. A scrotal septum separates the scrotum into two halves. This separation is obvious externally by the raphe between the right and left scrotal halves.

Congenital Anomalies

The congenital anomalies of the scrotum will be found in Table 25-2.

The cause of the venous dilation of varicocele is enigmatic. There is no solid embryologic or anatomic explanation for the condition. Varicocelectomy is the procedure of choice for testicular pain and infertility.

Accessory scrotum has been reported.66

Surgical Anatomy

Layers of the Scrotum

The scrotum houses the testes and the epididymis. It is composed of eight layers that are derived and modified from the six layers of the abdominal wall (Fig. 25-15). Although the layers are continuous, their terminology changes as they pass from abdomen to scrotum (Table 25-7).

Table 25-7. The Corresponding Layers of the Abdominal Wall and Scrotum

Abdominal Wall Scrotum
Skin Skin
Superficial fascia (Camper’s and Scarpa’s) Dartos and smooth muscle
External oblique (innominate) fascia External spermatic fascia
Internal oblique muscle and aponeurosis Cremasteric fascia and muscle
Transversus abdominis muscle and aponeurosis Cremasteric fascia and muscle
Transversalis fascia Internal spermatic fascia
Preperitoneal fat Preperitoneal fat
Peritoneum Tunica vaginalis

Source: Modified from Skandalakis JE, Colborn GL, Pemberton B, Skandalakis LJ, Gray SW. The surgical anatomy of the inguinal area — Part 2. Contemp Surg 38:28-38, 1991; with permission.

Fig. 25-15.

Scrotal layers. A, Cross section of scrotum and testes; B, Anterior view of left testis (the parietal layer of the tunica vaginalis and spermatic cord has been opened). (Modified from Gray SW, Skandalakis JE, McClusky DA. Atlas of Surgical Anatomy for General Surgeons. Baltimore: Williams & Wilkins, 1985; with permission.)

Scrotal Skin (Layer 1)

The first layer, the scrotal skin, is thin, pigmented, elastic, and corrugated. It is heavily fixed to the underlying superficial fascia. It contains many sebaceous glands that occasionally become cystic. In the midline is the raphe, the medial ridge, and the attachment of the septum.

Dartos (Layer 2)

The second layer, the dartos muscle or tunic, is the superficial fascia of the scrotum. It is formed by the blending of Camper’s fatty tissue, Scarpa’s membranous fascia, and smooth muscle fibers. The dartos tunic is continuous over the penis, forming its superficial fascia. In the perineum the adipose layer of Camper and the membranous layer, now called Colles’ fascia, again separate into more or less distinct layers. The first and second layers are scrotal in the strict sense.

The dartos tunic, composed of connective tissue and smooth muscle fibers, is fixed to the skin. Colles’ fascia is attached posteriorly to the urogenital diaphragm and laterally to the periosteum of the ischiopubic rami. In the perineum, Colles’ fascia lies superficial to the deep fascia which covers the superficial genital musculature.

A potential space, the superficial perineal cleft, is formed between Colles’ fascia and the muscular fascia (of Gallaudet) that opens anteriorly and superiorly into the subcutaneous space of the lower abdomen, between the membranous fascia of Scarpa and the deep muscle fascia of Gallaudet. Extravasated urine may collect in this space.

The deep fascia of the perineum (the fascia of Gallaudet or external perineal fascia) is continuous with Buck’s deep fascial layer of the penis.

External Spermatic Fascia (Layer 3)

The external spermatic fascia is the third layer. This is the scrotal continuation of the external muscle fascia of the abdominal wall, referred to as the fascia of Gallaudet or innominate fascia. This fascial layer is continuous over the penis as the deep fascia, or Buck’s fascia.

Cremaster Muscle (Layers 4 and 5)

The cremaster muscle is derived primarily from the internal oblique muscle, but may also include the transversus abdominis muscle. Although the fibers are striated, they are not under voluntary control.

Internal Spermatic Fascia (Layer 6)

The internal spermatic fascia is a prolongation of the transversalis fascia. Layers 3, 4, 5, and 6 form the coverings of the spermatic cord.

Preperitoneal Fat (Layer 7)

A layer of preperitoneal fat may or may not be present.

Tunica Vaginalis (Layer 8)

The tunica vaginalis is a serous membrane of peritoneum. Layers 7 and 8 are constituents of the cord.

Within these eight layers of the scrotum, the testes themselves move freely. Only the skin and the dartos are fixed. At the base of the scrotum, the scrotal ligament anchors the testis and deters torsion.

The subcutaneous superficial fascia in the scrotum contains little adipose tissue, this being replaced by smooth muscle that forms the tunica dartos scroti. The attachment of these muscle fibers to the skin forms the rugal folds of the scrotal skin.

Vascular Supply

Arteries

The scrotum is well supplied with blood. Branches of the superficial and deep external pudendal arteries (from the common femoral artery) supply the anterior part of the scrotum and anastomose with branches of the internal pudendal artery, which supply the posterior portion of the scrotum. The terminal branches in the scrotum lie transversely, so that exploration of the scrotum should be through a transverse incision to minimize bleeding. Good hemostasis is necessary to avoid hematomas. Good approximation of the dartos will help.

Veins

The veins draining the anterior scrotum follow the external pudendal arteries to empty into the great saphenous vein. Veins from the posterior scrotum follow the internal pudendal artery to become tributaries to the internal iliac vein.

Lymphatics

The skin of the scrotum, together with the perineal skin, is drained by lymph vessels that follow the external pudendal vessels to the superficial inguinal nodes.

Innervation

The skin of the anterior scrotum is innervated by anterior scrotal branches of the ilioinguinal nerve. There are some fibers from the external spermatic branch of the genitofemoral nerve that also supply the cremaster muscle. The posterior scrotum receives posterior scrotal nerves from the perineal branch of the pudendal nerve or the long scrotal branches of the posterior femoral cutaneous nerve.

Surgical Applications

For hydrocelectomy, two methods can be used. Excision of the tunica vaginalis uses continuous, oversewn absorbable sutures to ensure hemostasis. The “bottle neck” procedure involves incision of the tunica, erection of the edges, and suturing posteriorly to the epididymis by interrupted or continuous absorbable sutures (Fig. 25-16).

Fig. 25-16.

Hydrocelectomy: bottle neck procedure. (Modified from Skandalakis JE, Gray SW, Rowe JS Jr. Anatomical Complications in General Surgery. New York: McGraw-Hill, 1983; with permission.)

Anatomic Complications

Bleeding from the cut edge of the tunica vaginalis can be prevented by wrapping the scrotum with an elastic bandage for 24 hours. Pressure must be uniform and the bandage must be smooth to avoid local skin necrosis.

Seminal Vesicles

History

The anatomic and surgical history of the seminal vesicles is shown in Table 25-1.

Embryogenesis and Congenital Anomalies

The seminal vesicles (seminal glands) are formed from a lateral outgrowth of the caudal end of each mesonephric duct.

The congenital anomalies of the seminal vesicles are not well documented. They are associated with other malformations of the male reproductive system (see Table 25-2). These defects include unilateral or bilateral absence, duplications, and cysts.

Surgical Anatomy

The seminal vesicles are bilateral, saccular tubular glands (Figs. 25-17, 25-18). Each seminal vesicle measures approximately 5 cm x 1 cm; each is normally about 15 cm in length when uncoiled. The seminal vesicles are located at the posterior surface of the base of the bladder, lateral to the ductus deferens.

Fig. 25-17.

Seminal vesicles and deferent ducts.

Fig. 25-18.

Seminal vesicle unraveled. (Based on Basmajian JV, Slonecker CE. Grant’s Method of Anatomy, 11th ed. Baltimore: Williams & Wilkins, 1989.)

The topographic anatomy and relations of the seminal vesicles are as follows:

 

Anterior and superior: urinary bladder, occasionally fixed

Posterior and inferior: Denonvilliers’ fascia (the rectovesical septum) and anorectum

Above: peritoneum in the rectovesical fossa (may be occasionally reached by the tip of the seminal vesicles)

Medial: ductus deferens

Lateral: multiple vesicle vessels and levator ani

Below: ejaculatory duct, where it unites with the ampulla of the ductus deferens

Vascular Supply

Arteries

The blood supply to the seminal vesicle (see Fig. 25-13) is presented very succinctly by Hinman.44 We present his description:

The blood supply to the seminal vesicle is from the vesiculodeferential artery. This artery arises from the superior vesical artery or, more frequently, from the site where the internal iliac artery takes off from the umbilical artery.67 As it passes anterior to the ureter, it provides branches to that structure. At the seminal vesicle, it divides into three branches: (1) one to the bladder, (2) one to the vas, and (3) the largest to the anterior surface of the vesicle. This anterior vesicular artery divides on the surface of the vesicle to supply its anterior part. A second source of blood is the inferior vesicular artery, which may come either from the prostatovesical artery or directly from the gluteopudendal trunk. Its small branches supply the posterior portion of the vesicle and anastomose with branches of the anterior vesicular artery.

Veins

The veins follow the arteries, draining into the prostatic venous plexus and then to the internal iliac vein.

Lymphatics

The lymphatics drain into the external and internal iliac nodes together with the prostatic lymphatics. There are lymphatic interconnections with lymphatics from the ductus, the bladder, and the rectum.

Innervation

According to Macwhinney,68 the seminal vesicles are innervated by adrenergic fibers from the hypogastric nerve. If both sympathetic chain ganglia at the L1 spinal nerve level are removed by lumbar sympathectomy, sexual function may be affected.69 Loss of ejaculatory ability occurs in 54% of these cases, and impotence in 63%, according to Whitelaw and Smithwick.70

Erection is primarily due to parasympathetic neural control. The ejaculatory response is principally under sympathetic control until ejaculate reaches the penile urethra within which somatic motor innervation comes into play.

Histology

The mucosal folds of the seminal vesicles consist of pseudostratified epithelium with columnar or cuboidal cells. Their mucosa is composed of columnar epithelium with some goblet cells. The lamina propria is formed by connective tissue and some smooth muscle.

Physiology

The seminal vesicles do not store the spermatozoa, as some have thought. Spermatozoa are stored in the epididymis until the first phase of sexual excitement, when they are held in the ampulla of the ductus. Tanagho71 stated that the seminal vesicles have a considerable luminal storage capacity.

The seminal vesicles are secretory glands. The physiologic destiny of the seminal vesicles is to secrete a fluid which is responsible for the nutrition of the spermatozoa.

About 70% of the seminal fluid is formed in the seminal vesicle. Its complex secretion consists of water, mucoid fructose substances, potassium ions, prostaglandins, endorphins, fibronectin, and so on. When prostaglandin was first discovered it was so named because of the erroneous conclusion that it was secreted by the prostate. Soon it was discovered that, indeed, prostaglandin is secreted by the seminal vesicles, not the prostate. Fructose is produced nowhere else in the body, and provides a forensic determination of rape. The choline content, assayed as choline crystals, is the preferred test to determine the presence of semen (Florence test).

Emission of the ejaculate is effected by muscles that receive parasympathetic fibers and somatic nerve fibers from S2, 3, 4.

Surgical Applications

 

Normal seminal vesicles cannot be felt by rectal examination in the majority of cases.

Only seminal vesicles enlarged by disease (inflammatory process, etc) will be felt by rectal examination.

The inferior vesicular artery should be clipped or controlled prior to removal of the seminal vesicle to avoid troublesome bleeding.

Eastham et al.72 presented a case of seminal vesicle abscess secondary to tuberculosis.

Ejaculatory Ducts

History

The anatomic and surgical history of the ejaculatory ducts is shown in Table 25-1.

Embryogenesis and Congenital Anomalies

The ejaculatory ducts are formed from a portion of the mesonephric duct between the duct of the seminal vesicle and the urethra. Each ejaculatory duct is formed by the union of the ampulla of the ductus and the inferior part of the seminal vesicle.

Malformations of the ejaculatory ducts include agenesis, duplication, ectopia, congenital obstruction, and ureteric insertion into the duct.

Surgical Anatomy

The ejaculatory ducts pass distally through the prostate gland, with the posterior glandular part of the organ behind. The median lobe of the prostate is in front. The duct has a very thin wall, a length of approximately 2 cm, and a diameter of less than 1 mm. The ducts end as small openings on either side of the midline on the verumontanum of the urethral ridge (Figs. 25-19, 25-20).

Fig. 25-19.

Diagrams of cross-sections of prostate, showing ejaculatory ducts and verumontanum. Top diagram: Oblique transverse section through the terminal portions of ejaculatory ducts. A, Near median section (peripheral zone, anterior fibromuscular stroma). B, Sagittal section, 1 cm from median plane (transitional, central, peripheral zones). C, Sagittal section, 2 cm from median plane (peripheral zone, anterior fibromuscular stroma.) (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-20.

Ejaculatory duct shown in relationship to prostate. Axial cuts X and Y are through zones shown in small diagram. A, Proximal cut on plane X. Sagittal section on left, axial section on right. B, Distal cut on plane Y. (From Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993; with permission.)

Since a sphincter has not yet been found in this area, a fold of mucosa acting as a valve could be an obstacle, preventing retrograde passage of fluid up the ejaculatory duct. Perhaps the “curvy” pathway of the ducts is responsible for this action.66 It is possible that the ducts are compressed by prostatic glandular tissue, except in orgasm when internal pressure caused by the ejaculation opens the duct.

It is not known if the smooth muscle of the ejaculatory duct walls is a sphincterlike anatomic entity. Its tissue paper consistency makes it very vulnerable. It is easily torn from the prostate.

Histology and Physiology

Embryologically and anatomically, the ejaculatory duct is formed by the union of the seminal vesicle and the ampulla of the ductus deferens, so most likely their histology and physiology are the same.

Prostate

Introduction

For the many men suffering from prostate cancer throughout the world, we must continue our efforts to improve diagnosis, treatment, and basic understanding of this fatal disease. —Walsh and Brooks73

The author of this chapter most senior in age (JES, 67 at that time) had a complete physical examination by Dr. William M. McClatchey in March, 1987, which was reported as negative. Because of pain in his left knee, he had another partial examination in October, 1987.

WMcC: I want to do a rectal.
JES: But I had a rectal by you 6 months ago.
WMcC: My professor told me that not one patient will leave my office without a recent rectal examination.
JES: (Unwillingly) O.K.

Rectal exam revealed a prostatic nodule. Prostate specific antigen (PSA) from the earlier exam had been 0.3 ng/ml; the current report was 0.4 ng/ml. Both were within normal limits. But biopsy revealed adenocarcinoma. Radical prostatectomy by Dr. Sam Ambrose 2 weeks later revealed that the prostate (including its capsule) was full of cancer. Five years later an LHRH (luteinizing hormone-releasing hormone) agonist (Lupron) was started because the PSA had risen to 5.3 ng/ml. At present, Dr. Skandalakis is asymptomatic and the PSA is under 0.

History

The anatomic and surgical history of the prostate is shown in Table 25-1.

Embryogenesis and Congenital Anomalies

The prostate gland is formed around the end of the third month (first trimester) from the epithelium of the future prostatic urethra. The epithelium proliferates and penetrates the surrounding mesenchyme, which is the future fibromuscular prostatic tissue.

Congenital anomalies of the prostate will be found in Table 25-2. These include partial or complete agenesis, persistence of the anterior lobe, enlargement of the prostatic utricle, and heterotopic prostate. All these anomalies are rare.

Surgical Anatomy

Topographic Anatomy and Relations

The classical description of the adult prostate is that it has the size, shape, and consistency of a large chestnut. The form of the prostate is that of a compressed inverted cone: pyramidal, having a base and an apex. It is located between the vesical neck of the bladder and the apex of the urogenital diaphragm. According to Wilson et al.,74 the prostate apex is located above the ischial tuberosities in 99.3% of cases. This fact may help the radiologist-oncologist to deliver accurate external beam radiation.

The normal weight of the prostate in a young adult is from 17 to 19 g. The numbers 4, 3, 2 are useful as a mnemonic for remembering the transverse, vertical, and sagittal dimensions in centimeters, respectively, of the gland.

The prostate is enveloped by extraperitoneal connective tissues that cover the thin anatomic capsule (true capsule) of the organ, and it in turn envelops the proximal male urethra.

Fixation and Suspension

The following structures are responsible for the fixation of the prostate in its bed:

 

Puboprostatic ligaments

Urogenital diaphragm

Bladder

Prostatic sheath

Fascia of Denonvilliers

Steiner75 stated that the puboprostatic ligaments have a pyramidal shape that is part of a larger urethral suspensory mechanism which attaches the membranous urethra to the pubic bone (Fig 25-21).

Fig. 25-21.

Puboprostatic ligaments and dorsal vein complex.

Both males and females have a similar mechanism of suspension formed by 3 anatomic entities in continuity.

 

A condensation of the endopelvic fascia between the prostate and the levator ani forms the “white line” (Fig. 25-22). This band attaches posteriorly to the ischial spine, where it is continuous with the transverse fascial septum formed by the fascia of Denonvilliers. Anteriorly, the arcus tendineus of the fascia pelvis attaches to the pubic bone approximately 1 cm from the lower edge of the pubis about a centimeter lateral to the symphysis. This band is intimately continuous with the puboprostatic and pubourethral ligaments on either side of the midline. The puboprostatic ligaments connect the pubic bone with the capsule of the gland.

The fascial capsule (true capsule) of the prostate is continuous with the superior fascia of the urogenital diaphragm, the anterior thickened edge of which forms the transverse perineal ligament.

The intermediate pubourethral ligament is formed by the pubic arcuate and the transverse perineal ligaments.

Fig. 25-22.

Levator ani muscle (left half), showing levator muscle of prostate. (Modified from Last RJ. Anatomy Regional and Applied (5th ed). Baltimore: Williams & Wilkins, 1972; with permission.)

Steiner75 stated that the attachment of the urethral suspensory mechanism is inserted bilaterally into the lateral urethral border, forming a sling from the pubic arch. A good anatomic understanding of the relationship of the urethral suspensory mechanism to the urethra and its striated muscle sphincter and dorsal vein may facilitate apical dissection during radical retropubic prostatectomy. Proper prostatic apical dissection will minimize bleeding, ensure positive surgical margins, and reduce the likelihood of urinary incontinence.

Prostatic Urethra

The prostatic urethra (Fig. 25-23) begins at the urethral meatus at the apex of the trigone of the bladder. This opening is crescent-shaped, invaginated posteriorly by a protuberance caused by the underlying glandular tissue (median lobe of the prostate), thus forming the uvula vesicae. This is continuous with a posterior midline urethral ridge, or crest, in the urethra. The urethral ridge has a distinctly expanded portion called the verumontanum, or seminal colliculus. To better understand these structures, we can define some of the anatomic entities related to the prostate and the urethra (see also the discussion of the prostatic urethra in the male urethra section of this chapter).

Fig. 25-23.

Prostatic urethra. A, sagittal section. B, Oblique coronal view. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

The urethral crest is a ridge located on the floor of the posterior urethra between the bladder and the membranous urethra. It is wider at the vesical neck (the uvula) than on its pathway to the membranous urethra.

The verumontanum (colliculus seminalis) is a small elevated hillock at the middle area of the urethral crest.

The prostatic utricle or uterus masculinus is a crypt located in the middle portion of the verumontanum, approximately 6 mm deep. Garat et al.76 and Varlet et al.77 reported congenital dilatation of the utricle. Meisheri et al.78 urge that patients with an enlarged prostatic utricle be carefully examined to ascertain whether this condition is associated with female internal organs.

The orifices of the ejaculatory ducts are located on the right and left sides of the verumontanum.

The prostatic sinus is a depression located on the right or left side of the urethral crest, home of the openings of the prostatic ductules and the urethral glands.

Ureteric ectopia occurs most commonly in the prostatic urethra, and in the seminal vesicle with less frequency. If an ectopic ureter is in the seminal vesicle, a normal ipsilateral kidney is uncommon.

Prostatic Surfaces

There are four prostatic surfaces: one posterior, one anterior, and two inferolateral.

The posterior surface is flat transversely and convex vertically. It is separated from the rectal ampulla by the bilaminar fascia of Denonvilliers. This surface is characterized by a midline groove that is wider toward the base of the gland, and serves to partially separate the gland posteriorly into left and right lobes.

The posterior surface may be palpated by digital rectal examination. The vesicoprostatic junction is located at the upper border of the posterior surface.

The narrow and convex anterior surface is located between the apex and the base. Multiple large veins separate this surface from the symphysis pubis. According to Tanagho,71 the distance between the pubic symphysis and the anterior surface is approximately 2 cm.

The avascular puboprostatic ligaments are fibrous cords, wide or narrow. They connect the upper limits of the anterior surface of the prostate to the pubic bone, at the right and left sides of the cartilaginous area.

The right and left inferolateral surfaces are embraced by the anterior part of the levator ani muscles. They are fixed to the levator by the arcus tendineus of the fascia pelvis (“white line”), sagittal connective tissue bands between the ischial spine, and the pubic bone (Fig. 25-22). Here there is a very rich venous network and fibrous tissue which contributes part of the lateral prostatic sheath.

The levator prostatae muscle is the most anterior and most medial part of the levator ani muscle. These muscle fibers pass about the prostate gland and insert into the perineal body beneath the prostate gland, related to the anterior parts of the levator ani muscle. Thus, the muscle encroaches upon the prostate behind by a U-shaped sling (Fig. 25-22). Last79 astutely noted that “levator prostate” is not an apt term. We tend to agree; nonetheless, at orgasm, the pubococcygeus muscle contracts strongly and with this, the prostatic portion probably does, indeed, both lift and compress the prostate gland.

Fascia of Denonvilliers

In early fetal peritoneal development, the peritoneum extends downward as a pouch reaching the muscular pelvic floor and perineal body. Later the pouch disappears as the growing organs lift the peritoneal covering, resulting in fusion of the more anterior and posterior parts of the peritoneal covering, producing a bilaminar transverse septum. This septum is continuous with the peritoneum above and the perineal body below, and is continuous between the ischial spines. Layers unite with each other, forming a potential space. The union of these two layers produces the fascia of Denonvilliers.

Van Ophoven and Roth80 concluded: “Denonvilliers’ fascia consists of a single layer arising from fusion of the 2 walls of the embryologic peritoneal cul-de-sac. Histologically, it has a double-layered quality. The fascia of Denonvilliers extends from the deepest point of the interprostatorectal peritoneal pouch to the pelvic floor. A so-called posterior layer is in reality the rectal fascia propria.”

The potential space which was present embryologically between the two laminae discussed above may be retained as the space of Proust (Fig. 25-24). It has a strong anterior layer related to the prostate and a loose posterior layer related to the rectum. Jewett et al.81 were not able to demonstrate the plane of cleavage of the potential space within the two layers of the Denonvilliers’ fascia. It is more likely that the so-called posterior layer is in fact part of the lateral pillar of the rectum.

Fig. 25-24.

Fascia of Denonvilliers and space of Proust. White lines and arrows show various approaches for prostatectomy. (Modified from Healey JE, Hodge J. Surgical Anatomy (2nd ed). Philadelphia: BC Decker, 1990; with permission.)

Structure

Lowsley82 reported that the prostate gland can be divided into six lobes: anterior, posterior, median, subcervical, right lateral, and left lateral (Fig. 25-25). His description is no longer accepted, however, because it was based on studies of fetal and newborn prostates, and is not an accurate description of the adult gland.

Fig. 25-25.

Differing concepts of prostate lobes. Lowsley concept: P, posterior; M, median; A, anterior; L, lateral. McNeal concept: P, peripheral zone, C, central zone; Pr, prostatic sphincter. (Modified from Redman JF. Anatomy of the genitourinary system. In: Gillenwater JY, Grayhack JT, Howards SS, Duckett JW (eds). Adult and Pediatric Urology (2nd ed). St. Louis: Mosby Year Book, 1991, pp. 3-62; with permission.)

Avoiding use of the term “lobes” because of the confusion it engenders, McNeal83-85 described four regions or zones in the prostate: peripheral, central, transition, and anterior fibromuscular stroma (Fig. 25-26). The urethra is the key anatomic entity defining these regions (Figs. 25-26, 25-27, 25-28, 25-29, 25-30, 25-31, and 25-32). Posterior to the urethra is the glandular area. Anterior to the urethra is the fibromuscular area; that is, the ventral portion of the glandular prostatic tissue is covered by the fibromuscular stroma.

Fig. 25-26.

McNeal’s 4 anatomic regions of the prostate from an anatomic and pathologic standpoint. Percentages represent the proportion of each region to the prostate as a whole. (Modified from Tanagho EA. Anatomy of the lower urinary tract. In: Walsh PC, Retik AB, Stamey TA, Vaughn ED Jr (eds). Campbell’s Urology, 6th Ed. Philadelphia: WB Saunders, 1992; with permission.)

Fig. 25-27.

Zonal anatomy of the prostate as described by McNeal. The transition zone surrounds the urethra proximal to the ejaculatory ducts. The central zone surrounds the ejaculatory ducts and projects under the bladder base. The peripheral zone constitutes the bulk of the apical, posterior, and lateral aspects of the prostate. The anterior fibromuscular stroma extends from the bladder neck to the striated urethral sphincter. (Modified from Brooks JD. Anatomy of the lower urinary tract and male genitalia. In: Walsh PC, Retik AB, Vaughn ED Jr, Wein AJ (eds). Campbell’s Urology, 7th Ed. Philadelphia: WB Saunders, 1998; with permission.)

Fig. 25-28.

Diagram of prostate, sagittal plane. Relationships to other planes of section, coronal and oblique coronal, are shown by dotted lines. Coronal plane follows ejaculatory ducts and distal urethra. Oblique coronal plane follows proximal urethra to bladder. (Based on McNeal JE. The zonal anatomy of the prostate. Prostate 1981;2:35-49.)

Fig. 25-29.

Contour of prostate in coronal and oblique coronal planes. (Based on McNeal JE. The zonal anatomy of the prostate. Prostate 1981;2:35-49.)

Fig. 25-30.

Sagittal diagram of early embryo prostate shows area of stromal condensation. Laterally developing duct buds (circles) and proximally developing buds (in profile) shown in relationship to distal urethral segment and ejaculatory ducts, respectively. (Based on McNeal JE. The zonal anatomy of the prostate. Prostate 1981; 2:35-49.)

Fig. 25-31.

Coronal plane diagram of central zone and peripheral zone. Boundary between them marked by heavy lines radiating from verumontanum. Relationships are shown to the distal urethral segment, verumontanum, and ejaculatory duct stromal core. (Based on McNeal JE. The zonal anatomy of the prostate. Prostate 1981;2:35-49.)

Fig. 25-32.

Schematic diagram of adult prostate. Peripheral zone (PZ), central zone (CZ) and transitional zone (TZ) at apex of pre-prostatic sphincter (PPS). Seminal vesicles (SV) and ducti deferentes (DD) fuse to form ejaculatory ducts opening alongside verumontanum (V). (Modified from Chapple CR. Anatomy and innervation of prostate gland. In: Chapple CR (ed). Prostatic Obstruction: Pathogenesis and Treatment. New York: Springer-Verlag, 1994; with permission.)

To describe the prostate, McNeal uses three reference planes (Fig. 25-27): sagittal, coronal, and oblique coronal.

 

The sagittal plane bisects the prostate and incises the full length of the urethra, demonstrating its lumen. The urethra is thus the key anatomic entity related to all four of McNeal’s zones.

The coronal section shows both the distal urethra and the ejaculatory ducts in continuity with one another; that is, the ducts are parallel with the distal urethra.

The oblique coronal plane passes along the long axis of the proximal urethral segment, which cannot be seen in the coronal plane. It has an upward pathway through the bladder neck, transecting the base of the verumontanum.

McNeal84 wrote that marked histologic differences exist between the peripheral and central zones, suggesting important differences in biologic function. This information and some of the other findings from McNeal’s brilliant embryologic, anatomic, histologic, and pathologic observations are summarized below.

The 4 Zones of Mcneal from an Embryologic, Anatomic, Histologic, and Pathologic Viewpoint

Embryology (Speculative) 
Peripheral It is likely that the glands of this zone develop from the urogenital sinus and drain into the prostatic urethra.
Central Ducts of this zone are probably of wolffian origin.
Transition Glands in the transition zone are formed from the junction of the proximal and distal urethral segments.
Stroma This region is formed by nonglandular tissue.
Anatomy 
Peripheral Nearly 75% of the glandular prostate, the peripheral zone surrounds most of the central zone and much of the urethra; in other words, it surrounds the posterior and lateral areas of the prostate gland. Its glands drain into the prostatic urethra.
Central The central zone, which is nearly 25% of the glandular prostatic parenchyma, envelops the ejaculatory ducts and extends toward the base of the urinary bladder.
Transition This zone is less than 5% of the glandular prostate. The transition zone is composed of two minute glandular regions which are lateral to the preprostatic sphincter and directly related to the proximal urethral segment. The periurethral region is related to this zone and to the junction of the proximal and distal urethral segments. Periurethral ducts, which are responsible for the genesis of benign prostatic hyperplasia, are present.
Stroma The anterior fibromuscular stroma is nonglandular. It constitutes ⅓ of the prostatic tissue within the prostatic capsule but is in continuity with the detrusor muscle of the neck of the urinary bladder. It is heavily fixed with the anterior surfaces of the three glandular zones, and represents the periurethral gland region.
Histology 
Peripheral This zone is formed by multiple tubuloalveolar glands. The long, narrow ducts of this zone branch into small, round, regular acini with smooth, nonseptate walls. Epithelium is simple columnar; its pale cells have distinct borders and basally-placed small, dark nuclei.
Central The central zone is continuous with the peripheral zone and, like the peripheral zone, is formed by several tubuloalveolar glands (mucosal, submucosal, main prostatic) which are located around the urethra. The acinar tissue consists of large, irregularly shaped spaces; the walls have intraluminal ridges or septa. The cells of the central zone differ significantly from those of the peripheral zone. They have more opaque, granular cytoplasm and less distinct cell membranes. Their cell length varies, they have an irregular luminal border, and they appear more crowded. Their nuclei, which are slightly larger than those of the peripheral zone and stain paler, are displaced to variable levels from the basement membrane.
Transition In this zone one observes a minimal number of glands.
Stroma The fibromuscular stroma is composed of striated and smooth muscles, as well as elastin and collagen.
NOTE: The origin of the preprostatic sphincter described by McNeal is enigmatic; perhaps there is participation of wolffian and sinus tissue. 
Pathology 
Peripheral Most carcinomas develop in the peripheral zone.
Central Carcinoma seldom arises in the central zone.
Transition The transition zone and other periurethral glands are the exclusive site of origin of benign prostatic hypertrophy. The area near or within the sphincter almost invariably produces the most numerous and largest nodules. Ten to twenty percent of carcinomas may develop in the transition zone.
Stroma This area is without importance for prostatic function or pathology.

Wendell-Smith86 has summarized the structural and functional description of the prostate used in the 1998 edition of the Terminologia Anatomica,87 which blends the concepts of McNeal with findings of other workers on predilection for pathology and malignancy:

The use of the term lobe is confined to the right and left lobes and the variable middle lobe. The term lobule is used for the subdivisions, which are named from the anatomical position. Thus each side has a superomedial, an anteromedial, an inferoposterior, and an inferolateral lobule. Also necessary to describe a site of predilection is a peri-urethral gland zone. In ultrasound diagnosis, the trapezoid area is important: its upper limit is the rectoperinealis, its anterior limit is the intermediate part of the urethra, its lower limit is the anoperinealis, and its posterior limit is the anorectal junction. Confusion at the bladder neck is resolved by recognizing that the position of the internal urethral orifice varies with functional state of the bladder: when it is filling the orifice lies above the base of the prostate; when voiding begins, the orifice descends to the base of the prostate; between the filling internal orifice and the emptying internal orifice is the bladder neck part of the urethra.

We recommend Wendell-Smith’s comprehensive article to the interested student.

Hricak et al.88 studied the normal anatomy of the prostate by MRI. They reported that zones were seen very well. Cornud et al.89 used endorectal MRI to study the zonal anatomy of the prostate. They reported clearly delineated anatomic boundaries of the transition zone, the prostatic capsule, the neurovascular bundles, and the caudal junction of the ejaculatory ducts.

Some workers believe that approximately 70-80% of prostatic cancers may develop in the peripheral zone. Cancer may develop in the central zone at a rate of only 5-10%. Remember: when a nodule forms, it can be palpated by rectal digital examination. Benign prostatic hyperplasia may appear lobar by digital examination, although the normal, nonhyperplastic prostate lacks lobar configuration.90

Reese et al.91 suggested that the central zone of the prostate may be the selective site of origin of proteolytic enzymes in seminal fluids.

Capsules of the Prostate

There are three capsules of the prostate; two (the true and false) are anatomic (Fig. 25-33), the third is pathologic (Fig. 25-34).

Fig. 25-33.

Capsules of prostate.

Fig. 25-34.

Surgical anatomy of prostatectomy. A, Normal prostate (vertical section). B, Prostatic adenoma (benign hypertrophy) compresses normal prostatic tissue into false capsule. C, Prostatectomy removes adenoma but leaves capsule. (Modified from Ellis H. Clinical Anatomy (6th ed). Oxford UK: Blackwell Scientific, 1980; with permission.)

The true capsule is a very thin covering surrounding the gland in toto.

The false capsule (periprostatic fascia or prostatic sheath) is an extraperitoneal fascia (visceral layer of endopelvic fascia). This capsule is continuous with 4 fasciae:

 

Anterior: fascia of the bladder, puboprostatic ligament

Lateral: arcus tendineus of the fascia pelvis

Posterior: fascia of Denonvilliers

Inferior: superior fascia of the urogenital diaphragm

Between the true and false capsules is a venous plexus, the prostatic or pudendal venous plexus (Fig. 25-33).

Part of the normal aging process is progressive prostatic growth due to benign prostatic hyperplasia (BPH). The peripheral part of the prostate becomes compressed against the surrounding endopelvic connective tissue, forming a surgical capsule (pathologic capsule). When enucleation of the prostate is performed, the plane between the compressed peripheral tissue and the adenomatous tissue permits removal of the adenoma, leaving behind the peripheral condensed prostatic tissue and the anatomic capsule.

The pathologic capsule is formed of essentially normal prostatic tissue peripheral to an adenoma, compressed against the false capsule (Fig. 25-34B). This remains after enucleation of the adenoma (Fig. 25-34C).

DiLollo et al.92 studied the morphology of the prostatic capsule and its posterosuperior region. They advised the following:

[I]n the prostatic zone limited by the ejaculatory ducts, the ventral surface of the seminal vesicles and the basal portion of the urinary bladder, there is no real connective tissue barrier around the prostate; on the contrary, a rich vascular network is present. Thus, a malignant tumor which begins in this zone should be considered from the very early stages potentially extracapsular. It is important to note that the present conclusions confirm the earlier observations of Denonvilliers.

Vascular Supply

Arteries

According to Clegg,67 there are three arterial zones within the prostatic parenchyma: anterior or capsular, intermediate, and urethral.

Characteristically, the urethral vessels enter the prostatovesical junction at 7 to 11 o’clock and at 1 to 5 o’clock. The two sides have few anastomoses.

The blood supply of the prostate is derived primarily from the inferior vesical artery (Fig. 25-35). A branch of this artery enters the prostate laterally at the prostatovesical junction. This artery divides into two branches, the peripheral and the central. The peripheral branch serves the majority of the prostatic parenchyma; the central branch supplies the urethra and the periurethral tissues.

Fig. 25-35.

Arterial supply to prostate. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Other arteries contributing rami to the prostate are the internal pudendal and middle rectal arteries. Last79 considered the middle rectal artery to be poorly named, since most of its blood goes to the prostate gland.

Remember that an accessory pudendal artery may arise in the pelvis and pass under the pubic arch with the deep dorsal vein to reach the penis. Such arteries usually arise from a branch of the anterior division of the internal iliac artery. Accessory pudendal arteries can arise unilaterally or bilaterally from the obturator artery, the internal pudendal artery prior to its exit from the pelvis, or directly from the internal iliac or the superior and inferior vesical arteries. The accessory pudendal artery leaves the pelvis by passing through the hiatus between the pubic arcuate ligament and the transverse perineal ligament.

An accessory pudendal artery may provide the dorsal artery of the penis, the deep artery to the corpus cavernosum, or both. Such branches are divided during radical prostatectomy. Their frequency of occurrence is only about 3% in females, but 10% in males.93 This artery is always present in lower animals, and is called the urogenital artery, because it supplies the bladder.94,95

Veins

There is a rich venous plexus (prostatic plexus) (Fig. 25-36) between the prostate gland and the prostatic sheath. It communicates with the internal iliac venous system and the presacral veins. The prostatic venous plexus receives the deep dorsal penile vein and the veins of the base of the bladder. The vesical and internal iliac veins receive most of the venous blood.

Fig. 25-36.

Venous drainage of prostate. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

It has been said that the prostatic venous plexus does not have any valves. Part of the blood drains toward the extradural venous plexus of Batson;96 this suggests an explanation for the metastasis of cancer of the prostate to the spine and skull.

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The deep dorsal vein of the penis reaches the prostatic venous plexus by passing through the cleft between the pubic arcuate ligament and the transverse perineal ligament of the urogenital diaphragm. According to Redman,97 the vein trifurcates upon emerging through the opening, with a pathway toward the anterior lateral parts of the prostate, thereby forming Santorini’s plexus. In the laboratory, we have seen low bifurcation. In cases of uncontrolled bleeding from the dorsal venous plexus during radical retropubic prostatectomy, the deep dorsal vein of the penis can be ligated.

Lymphatics

From the prostatic acinus, large intraprostatic trunks are formed. These penetrate the prostatic capsule and form the periprostatic lymphatic plexus. This plexus yields lymphatic vessels which follow the vascular network of the prostatovesical arteries.

The lymph vessels that follow the prostatovesical arteries travel to the internal iliac lymph nodes (Fig. 25-37). The vessels also travel to the presacral lymph nodes and, occasionally, to the external iliac lymph nodes.

Fig. 25-37.

Lymphatics of prostate. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Hinman66 emphasized that from a surgical standpoint, the primary sites of lymphatic drainage of the prostate are the obturator and external iliac nodes. He also stated that the presacral and presciatic nodes are less important as initial sites of prostatic lymphatic drainage. Hinman also mentioned the work of Whitmore and Mackenzie,98 McLaughlin et al.,99 and Wilson et al.100

The histologic studies of the glandular prostate by Fukuda et al.101 demonstrated a high lymphatic density in the midbase region surrounding ejaculatory ducts. The authors concluded that the midbase region might be a route of lymphatic spread of prostate cancer.

Metastasis to other anatomic entities such as the penis102 may occur.

Innervation

The preganglionic sympathetic nerve supply to the smooth muscle of the seminal vesicles, ejaculatory ducts, and prostate gland arises in the intermediate gray area of spinal cord levels L1 and L2 (or L3). Postganglionic fibers arise in the preaortic or pelvic plexuses. The sympathetic fibers cause contraction of the smooth muscle and expulsion of seminal fluid.

Parasympathetic fibers from sacral cord levels S2, S3, and S4 synapse in pelvic ganglia and periprostatic ganglia. They act perhaps to dilate blood vessels and stimulate secretion from glands of the genital system, including the prostate.

The neurovascular bundles described by Walsh and Donker103 are located on the dorsolateral surface of the prostate gland between the rectal wall and the prostate (Fig. 25-38). They are concealed within the periprostatic fascia. These nerve plexuses include branches of the preganglionic parasympathetic visceral efferent fibers (nervi erigentes or pelvic splanchnic nerves with cell bodies in the intermediolateral cell column of S2-S4), sensory fibers, and sympathetic fibers. Although these nerves are very small, their anatomic location can be estimated by looking for the capsular vessels. Preserve the neurovascular bundles during “nerve sparing” radical retropubic prostatectomy by avoiding tissues that are located posterolaterally. This may prevent impotence. Klotz104 advocates intraoperative cavernous nerve stimulation during radical prostatectomy to optimizing nerve sparing since these nerves are often difficult to visualize and may have a variable course.

Fig. 25-38.

Topography of neurovascular bundle.

Carlton105 stated that visualization of the neurovascular bundle is better with perineal prostatectomy than with retropubic prostatectomy. The neurovascular bundle may be saved during prostate surgery by rotating the bladder and elevating the ureter, with close division of the tissues around the wall of the urinary bladder.

We quote Baskin et al.106:

Perforating branches from the dorsal lateral neurovascular bundle do not exist based on serial step sectioning and microscopic examination of male genital specimens. Surgically it is possible to elevate the neurovascular bundle but the dissection needs to remain directly on top of the tunica albuginea to prevent neuronal injury. Small perforating branches into the urethral spongiosum may be injured with unknown significance. We continue to advocate plication in the nerve-free zone at the 12 o’clock position for correction of penile curvature.

It has become evident that four factors are involved in maintaining erectile function following radical prostatectomy: preservation of the neurovascular bundle, tumor category, age, and preservation of accessory pudendal arteries. Of these factors, preservation of the neurovascular bundle appears to be most important. Catalona and Basler107 reported potency rates of 63% and 41% of patients undergoing bilateral and unilateral nerve-sparing radical prostatectomy, respectively. Investigators from Stanford University108 report less favorable results: that the ability to achieve unassisted intercourse with vaginal penetration occurred in 1.1% of men having non-nerve sparing radical prostatectomy, 13.3% with unilateral neurovascular bundle preservation, and 31.9% with bilateral neurovascular bundle preservation. Quinlan and associates109 noted that advancing tumor categories and age result in lower potency rates. Polascik and Walsh110 have discovered that when present, preservation of the accessory pudendal artery significantly increases potency rates among men undergoing radical prostatectomy.

For patients with clinically localized prostate cancer, Ghavamian and Zincke111 advocate nerve dissection starting at the lateral aspect of the prostate with secondary urethral dissection to decrease dissection around the striated sphincter.

Histology

Seventy percent of the weight of the prostatic mass is glandular epithelium. Thirty percent is fibromuscular, mainly non-striated. The glandular part contains ducts and acini which are lined with columnar epithelium and drain in the posterior and lateral walls of the prostatic urethra.

According to McNeal,84,85 the three glandular regions of the prostate differ histologically and biologically. In all regions, ducts and acini are lined with secretory epithelium, with a layer of basal cells and interspersed endocrine-paracrine cells beneath. The peripheral zone has small, rounded, uniform glands. The central and transitional zones have very large and irregular acini.

Perhaps autocrine, paracrine, endocrine (androgen-sensitive or androgen-insensitive), and other unknown factors play a role in the regulation and control of the growth of the prostate. Therefore, growth as well as metastasis of prostatic carcinomas may be controlled or altered by the above factors.

Enzyme-histologic studies of Zaviacic112 support the belief that the prostate and the urethral and paraurethral glands in the female are homologous.

Physiology

The prostate gland secretes a milklike alkaline fluid. This fluid is very important for the fertilization of the ovum, since sperm within both the ductus deferens and vaginal tissue produce fertilization-inhibiting acidity. Guyton113 stated that prostatic fluid most likely neutralizes the acidity of the fluids of the ductus deferens and vagina after ejaculation, enhancing the motility and fertility of the sperm. The prostatic fluid also contains citric acid, calcium, phosphorus, and other substances.

We quote Hayward and Cunha114:

The development of the prostate is controlled by steroid hormones that in turn induce and maintain a complex and little understood cross talk between the various cell types making up the gland. The result of this intracellular communication can be either new growth or growth quiescence, depending upon the differentiation state of the cell type being stimulated. Secretory function of the prostate is dependent upon direct stimulation of fully differentiated prostatic epithelial cells by androgens. The prostate thus seems to be regulated in a similar manner to other organs of the male and female genital tract with proliferative control mediated by cell-cell interactions, whereas differentiated function is determined by direct steroid action on the parenchymal cells.

Surgical Applications

 

Remember Healey and Hodge’s115 axiom about the space of Proust: “It has been the lament of many that it is not always easy to find this passage between ‘wind and water.'”

The prostate will hypertrophy after middle age, causing partial or total obstruction of the prostatic urethra.

The thick fibromuscular parenchyma anterior to the urethra forms the anterior third of the prostate. It may undergo fibromuscular hypertrophy, but not glandular hypertrophy.

The transition zone lateral to the preprostatic sphincter is probably responsible for the origin of all prostatic hyperplasias, but almost never for malignancy.

The peripheral zone is the site most commonly responsible for the formation of malignant nodules.

The urogenital sinus is most likely responsible for the embryogenesis of the peripheral and transition zones, as well as of the periurethral glands.71 The wolffian duct appears to be responsible for the genesis of the central zone, and thus may be a factor in the resistance of this zone to the formation of cancer.

McNeal116 stated:

 

– Cancer originates from the peripheral and transition zones.

– Benign nodular hyperplasia may also develop in these two zones.

– Cancers with a volume of more than 5 cc and poor differentiation are the most likely to metastasize.

– Morphologically favorable cancers have a volume of less than 4 cc; unfavorable cancers have a volume of more than 12 cc.

– Metastasis to lymph nodes is strongly related to the size of the cancer and the percentage of high-grade tumor.

With enucleation, the urologist’s index finger is introduced between the benign prostatic mass and the pathologic capsule. This avoids the prostatic venous plexus, which is external to this plane.

There are several approaches to the prostate gland:

 

– Transurethral resection (TUR)

– Transabdominal approach (through the urinary bladder)

– Radical retropubic approach (through the space of Retzius)

– Perineal approach

An excellent article by Carlin and Resnick117 provides detailed descriptions of the anatomic entities related to radical perineal prostatectomy, from outside to deep, in order to “integrate this knowledge with the surgical approach to the radical perineal prostatectomy.” The entities they describe are:

 
 

– Skin

– Subcutaneous tissues

– Colles’ fascia

– Superficial transverse perineus muscle (Fig. 25-39)

– Deep transverse perineus muscle

– Central tendon (perineal body)

– Pelvic floor musculature

– Anorectum and external anal sphincter (Fig. 25-39)

– Rectourethralis muscle (Fig. 25-40)

– Denonvilliers’ fascia (Figs. 25-41, 25-42, 25-43, and 25-44)

– Neurovascular bundle and neuroanatomy (Figs. 25-43, 25-45)

– Vascular supply (Fig. 25-46)

Fig. 25-39.

Pelvic floor musculature. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-40.

Rectourethralis muscle. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-41.

Mid-sagittal section of the male pelvis. Dashed blue lines show various approaches for perineal prostatectomy. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-42.

Transverse section of male pelvis shows fascial layers surrounding prostate gland. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-43.

Transverse section of prostate gland shows anatomy of fascia of Denonvilliers and neurovascular bundles.

Fig. 25-44.

Sagittal oblique view of male pelvis.

Fig. 25-45.

Neuroanatomy of male pelvis. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-46.

Diagrammatic representation of posterior vascular supply to prostate. (Based on Carlin BI, Resnick MI. Anatomic approach to radical perineal prostatectomy. Urol Clin North Am 1995;22:461-473.)

 

In the perineal approach, with division of the central fibromuscular perineal body, the anterior and posterior layers of the potential space of Proust should be identified. This serves not only to protect the rectum, but also to avoid bleeding.

Remember that the lower rectal wall is heavily fixed to the apical part of the prostate and, therefore, to the proximal urethra. The rectourethralis muscle might be responsible for this stout attachment. The proximity of the peritoneum in the rectovesical fossa must be borne in mind when using the perineal approach. This is the area where rectal perforation most commonly occurs during radical prostatectomy. When peritoneum in the rectovesical area is inadvertently opened, it is easy to think that the rectum has been perforated. Awareness of the anatomy will help in this situation.

Koch118 reminds us that knowledge of the prostatic dorsal venous anatomy facilitates dissection of the prostatic apex with little bleeding and with preservation of the rhabdosphincter, urethra, and neurovascular bundles.

We are grateful to Dr. P.C. Walsh, who allowed us to reprint verbatim the anatomy of radical prostatectomy.119

Radical perineal prostatectomy was first developed at The Johns Hopkins Hospital in 1904 by Hugh Hampton Young120 and the retropubic approach was introduced in 1947 by Terrance Millin.121 Although rad-ical prostatectomy provided excellent cancer control, it never gained widespread popularity because of major side effects. Virtually all men who underwent radical prostatectomy were impotent, many had significant urinary incontinence, and when performed via the retropubic approach, excessive bleeding was common. With the introduction of external beam radiotherapy for the treatment of prostate cancer, by 1970 radical prostatectomies were rarely performed.

Recognizing that there was no better way to cure organ confined disease than to remove the primary organ, in 1974 I embarked on a series of anatomical studies in an attempt to understand the source for this morbidity with the hope that it might be avoided. In retrospect, it became clear that impotence was universal because the location of the autonomic innervation to the pelvic organs and the corpora cavernosa was not known, incontinence was common because the anatomical understanding of the sphincteric complex was incorrect, and excessive bleeding occurred because the anatomy of the dorsal venous complex and Santorini’s plexus was not charted. This deficit in the understanding of the peri-prostatic anatomy can be traced to the use of adult cadavers, which were not ideal for these investigations. The agents used for tissue fixation dissolve adipose tissue, thus obscuring normal tissue planes and the pelvic viscera compress the pelvic organs into a thick pancake of tissue, making anato-mical dissection difficult. . . [T]hese problems were overcome by intra-operative anatomical dissections, and the use of infant cadavers for anatomical studies.

Anatomy of the Dorsal Venous Complex

During radical retropubic prostatectomy, excessive bleeding was common because the large venous complex that travels over the anterior surface of the urethra and prostate must be divided. This venous complex is covered by a thick sheath of dense fascia, which obscures the anatomical location of the venous tributaries. Anatomical studies showed that the deep dorsal vein leaves the penis under Buck’s fascia between the corpora cavernosa and penetrates the urogenital diaphragm dividing into three major branches: the superficial branch and the right and left lateral venous plexus.122 The superficial branch lies outside the pelvic fascia but the common trunk and lateral venous plexuses are covered and concealed by this fascia (Fig. 25-47). The lateral venous plexuses travel posterolaterally and communicate freely with the pudendal, obturator, and vesicle plexus. These anatomical observations made it possible to devise major alterations in the surgical technique that avoided excessive bleeding:

Fig. 25-47.

Santorini’s venous plexus. A, Trifurcation of dorsal vein of penis shows relationship of venous branches to puboprostatic ligaments (supine view). B, Anatomic relationship at trifurcation (lateral view, lateral pelvic fascia removed). (Modified from Reiner WB, Walsh PC. An anatomical approach to the surgical management of the dorsal vein and Santorini’s plexus during radical retropubic surgery. J Urol 1979;121:198-200; with permission.)

 

1. The endopelvic fascia was opened adjacent to the pelvic sidewall to avoid injury to the lateral venous plexus.

2. The puboprostatic ligaments were divided with care not to injure the superficial branch of the dorsal vein nor to enter the anterior prostatic fascia covering Santorini’s plexus and the dorsal venous complex.

3. The common trunk of the dorsal vein over the urethra was isolated with a right angle clamp, transected, and ligated, thus avoiding most of the major bleeding associated with this procedure. The development of this technique made the operation safer and provided a relatively bloodless field which made it possible to view the periprostatic anatomy in a way not possible previously. Shortly after this technique was developed, a patient reported that he was fully potent after surgery. This patient continues to do well 20 years postoperatively. Based on that experience, I questioned why any man was impotent after radical prostatectomy. At this time it was believed that impotence after radical prostatectomy was neurogenic in origin, and that it was caused by injury to the cavernous nerves that traveled through the prostate. For this reason, it was assumed that impotence was a necessary complication of a radical prostatectomy. From this one experience, I knew that was not true.

Autonomic Innervation of the Corpora Cavernosa

The autonomic innervation to the corpora cavernosa is derived from the pudendal nerve and the pelvic plexus. The pudendal nerve provides both autonomic supply to the corpora cavernosa and sensory supply to the skin. Because the pudendal nerve is not close to the operative field, and because sensation is intact in impotent men after surgery, injury to the pudendal nerve could not be implicated. Rather, it was assumed that injury to the pelvic plexus or its branches must be responsible. The pelvic plexus provides autonomic innervation to all of the pelvic organs but, until the time of this work, the exact location of the pelvic plexus and the branches to the corpora cavernosa in man was not known.

In 1981 I had the opportunity to perform fetal dissections with Dr. Pieter Donker, Emeritus Professor of Urology at Leiden University, The Netherlands. Dr. Donker identified the fetus as an ideal model for these studies because the fibrofatty tissue was less abundant, the pelvic structures were not disturbed by the pressure of the abdominal viscera, and the nerves were correspondingly larger in relationship to adjacent structures. At the time that I met Dr. Donker, he was performing dissections of the pelvic plexus to characterize the autonomic innervation to the bladder. After informing him that the branches of the pelvic plexus to the corpora cavernosa were also not known, we traced these pathways in stillborn male infants. The pelvic plexus, which provides autonomic innervation to all of the organs, rests on the lateral surface of the rectum. The branches that innervate the corpora cavernosa were seen clearly outside the capsule of the prostate and its surrounding tissue as they travel between the prostate and rectum before penetrating the urogenital diaphragm and innervating the corpora cavernosa103. . .This study showed clearly that the prostate could be removed completely with preservation of these nerves. This study provided the schematic anatomy of the pelvic plexus and cavernous nerves. Next, landmarks in the adult needed to be developed.

In the operating room, it became clear that the capsular arteries and veins of the prostate were located in the same region as the cavernous branches. This finding suggested that these vessels may serve as the scaffolding for these microscopic nerves and that the neurovascular bundle could be used as a visual landmark for their identification. To confirm this impression, an adult cadaver was perfused completely with Bouin’s solution shortly after death. The pelvic organs were removed en bloc, 10,000 whole-mount step sections were prepared, and a 3-dimensional reconstruction performed.123 This 3-dimensional reconstruction showed clearly that the cavernous nerves did travel in association with the capsular arteries and veins of the prostate outside the capsule and fascia of the prostate. Armed with these findings, we characterized the full neuroanatomy of the male pelvis using dissections performed in fresh cadavers.124 This study showed that the pelvic plexus is located 5-11 cm from the anal verge traveling on the lateral surface of the rectum with its midpoint at the tip of the seminal vesicle. After providing branches to the bladder, lower ureter, and prostate, the branches from the pelvic plexus travel in association with the capsular arteries and veins of the prostate dorso-lateral to the prostate, where the nerves exit to innervate the corpora cavernosa.

Anatomy of the Striated Sphincter Continence Mechanism

For years it was widely believed that the urinary continence mechanism in man was composed of a group of horizontally oriented pelvic floor muscles contained in the levator ani complex. However, in 1980 Oelrich showed that the sphincteric complex responsible for passive urinary control was a vertically oriented tubular sheath.125 In utero, this sphincter extends without interruption from the bladder to the perineal membrane. As the prostate develops from the urethra, it invades the sphincter muscle thinning the overlying parts and causing a reduction or atrophy of some of the muscle. In the adult, at the apex of the prostate the fibers are circular and form a tubular striated sphincter surrounding the membranous urethra (Fig. 25-48). Thus, as Myers and colleagues have shown, the prostate does not rest atop a flat transverse urogenital diaphragm like an apple on a shelf with no striated muscle proximal to the apex.126 Rather, the external striated sphincter is more tubular and has broad attachments over the fascia of the prostate near the apex. This anatomy had important implications in transection of the dorsal vein complex (which is intimately associated with the striated sphincter), the apical dissection, and reconstruction of the urethra.127

Fig. 25-48.

A, Cross-section of urethra just distal to apex of prostate demonstrating inner circular layer of smooth muscle, outer striated urethral sphincter, perineal body. B, Anatomic relationship of prostate to pelvic fascia, pelvic plexus, neurovascular bundle (NVB). Window of fascia removed to illustrate prostatic capsule. Note attachment of striated urethral sphincter to apex of prostate. SV, seminal vesicle. (Modified from Walsh PC. Anatomic radical prostatectomy: cancer control with preservation of quality of life. In: Fortner JG, Sharp PA (eds). Accomplishments in Cancer Research 1996. Philadelphia: Lippincott-Raven, 1997, pp. 41-53; with permission.)

Pelvic Fascia

The prostate is covered with two distinct and separate fascial layers: Denonvilliers’ fascia, which covers the posterior surface of the prostate, and the lateral pelvic fascia, which covers the pelvic musculature. This fascia has also been called the prostatic fascia. All of these fascial layers are intimately associated with the dorsal vein complex, the neurovascular bundle, and the striated sphincter (Fig. 25-48). These intimate relationships must be well understood in order for the surgeon to completely remove localized prostate cancer.

Anatomic Complications

Transurethral Resection

Complications of transurethral resection include:

 

Bleeding from the prostate parenchyma or bladder neck

Injury of the bladder wall and prostatic capsule or intraperitoneal perforation into the space of Retzius

Urethral strictures at the membranous urethra, penoscrotal junction, or fossa navicularis

Incontinence

Bleeding from the prostate parenchyma or bladder neck may occur with transurethral resection. Catheter traction will usually stop bleeding, if electrocautery is not successful. According to Smith,128 the most common area for bleeding is the anterior bladder neck. The surgeon must visualize and inspect the prostatic fossa thoroughly. Occasionally, exploration, complete enucleation of the adenoma, direct fulguration/electrocautery and/or ligation may be necessary. The prostatic urethra as well as the prostatic fossa may be compressed with a balloon catheter to stop bleeding, if necessary.

Another complication is injury of the bladder wall and prostatic capsule, or intraperitoneal perforation into the space of Retzius. With intra- or extraperitoneal injury, laparotomy and repair should be performed. Small extraperitoneal perforations usually respond to prolonged Foley catheter drainage.

Urethral strictures may form at the membranous urethra, the penoscrotal junction, or the fossa navicularis. A soft and gentle technique is the only prophylactic measure against urethral strictures.

Incontinence may follow transurethral resection. There are two functional sphincters for urinary control. One, the internal sphincter, is at the bladder neck; this is the sphincter typically damaged during transurethral prostatectomy (TURP). Thus, after TURP, the patient is more reliant on the external sphincter. The best method to prevent incontinence is to avoid damage to the external sphincter caused by overzealous resection.

Anticholinergic treatment is used in dealing with incontinence resulting from sphincter damage; urologists try anticholinergics because their use is simple. Alpha-receptor stimulators, such as Ornade, are beneficial to some patients.

Transabdominal Approach

Complications of the transabdominal approach (through the urinary bladder) include:

 

Damage to the external sphincteric apparatus

Injury to the posterior capsule with injury to the seminal vesicles

Bleeding at the bladder neck

To avoid damage to the external sphincteric mechanism, the surgeon must cut apical attachments very carefully.

Inspect the prostatic fossa for bleeding or injury of the seminal vesicles. If injury to the seminal vesicles is discovered, repair the posterior capsule and anastomose it to the bladder neck.

Bleeding at the bladder neck can be controlled by ligating bleeding points using figure of eight at 5 and 7 o’clock with 2-0 absorbable sutures. If bleeding continues, a purse-string suture around the bladder neck should be considered.

Radical Retropubic Approach

Complications of radical retropubic prostatectomy (through the space of Retzius) include:

 

Bleeding

Rectal injury

Ureteric injury

Obturator nerve injury

Impotence

Bladder neck contracture

Incontinence

Venous bleeding is the most common intraoperative complication during radical retropubic prostatectomy. The anatomic entities involved are the venous plexuses around the prostate and the deep dorsal vein of the penis; these are referred to collectively as the dorsal venous complex. During lymphadenectomy, any branch of the internal iliac vein can be involved.

To avoid venous bleeding

 

Incise the endopelvic fascia carefully under direct vision. Large veins may lie directly behind the endopelvic fascia. These may be controlled with cautery or ligature.

Carefully ligate the dorsal venous complex.

Carefully divide the puboprostatic ligaments. Approach from lateral to medial. Blunt dissection between the puboprostatic ligaments will almost always cause bleeding. When transecting the puboprostatic ligaments, take care to avoid branches of the dorsal venous complex; these are located immediately behind the ligaments.

After successful control of the previous elements, follow with careful exposure of the prostatic apex. This cannot be accomplished unless the incision, ligation, and division described above have been followed.

Epidural anesthesia may result in a “regional” hypotension which can decrease blood loss.

Walsh129 advises bulldog clamps to both hypogastric (internal iliac) arteries for reduction of blood flow to the prostate. Beware of the artery to the seminal vesicle at the very tip of the seminal vesicle; it can cause troublesome bleeding.

Rectal injury is very rare (1% according to Borland and Walsh130). It most commonly occurs during dissection of the apex of the prostate. This is where the prostatic fascia is most adherent to the rectal fascia. Upward retraction of the prostate will tent the rectum; this can increase the risk of iatrogenic injury to the rectum.

Close a rectal laceration in two layers. Interpose omentum between the rectum and the vesicourethral anastomosis through a small peritoneal opening. Administer antibiotics during and after surgery, along with copious irrigations. Rarely, it may be necessary to perform a diverting colostomy. However, if the bowel has not been prepared, the surgeon must weigh that risk when deciding whether the colostomy is appropriate.

Ureteric injury may occur after the lateral, anterior, and posterior surfaces of the prostate are free. Then the prostate is attached only to the bladder. Administer indigo carmine to assist in identifying the ureteric orifices. Incise the anterior bladder neck, and identify the orifices. Then, dissect the posterior bladder neck from the prostate, seminal vesicles, and ampullae of the ducti deferentes. Ureteric reimplantation is advised in instances of ureteric injury close to the trigone.

Division injury of the obturator nerve at the pelvic sidewall requires end-to-end re-anastomosis. Division of the obturator nerve will be followed by paralysis of the adductor muscle group, the gracilis, and the obturator externus. A sensory deficit will also be present along the medial part of the thigh.

Impotence is the result of excision of the neurovascular bundle (which was described previously with the innervation of the prostate). According to Walsh,129 the father of nerve-sparing prostatectomy, “A number of factors may be responsible for postoperative impotence other than injury to the cavernous nerves.”

Bladder neck contracture (vesicourethral anastomotic stricture) can be avoided by good mucosa-to-mucosa apposition of the bladder neck and the urethra. Use six interrupted 2-0 absorbable sutures at 2, 5, 7, and 10 o’clock.

Incontinence can be prevented by avoiding injury to the muscles of the pelvic floor and by leaving as much urethral length as possible. The surgeon should perform a good mucosa-to-mucosa vesicourethral anastomosis. Use of alpha-adrenergic agonists, anticholinergics, etc, is recommended.

Steiner131 lists the anatomic components of the urethral sphincter complex whose preservation is necessary for continence:

 

entire circumference of rhabdosphincter musculature

periurethral fascial investments (pubourethral ligaments anterolaterally and median fibrous raphe posteriorly)

The innervation of the rhabdosphincter is preserved by way of the intrapelvic branch of the pudendal nerve (somatic). The innervation of the mucosal and smooth muscle components is preserved by way of the urethral branch of the inferior hypogastric plexus (autonomic).

Perineal Prostatectomy

Complications of the perineal approach to the prostate include:

 

Inability to identify the anterior rectal fascia and the pathway to the prostate and prostatic apex

Bleeding

Bladder neck injury and occlusion of ureteric orifices

Urinary perineal leakage

Stricture at the urethrovesical anastomosis

Incontinence

Impotence

The inability to find the pathway to the prostate by failure to identify the anterior rectal fascia is a true anatomic complication. Incise the central tendon very carefully. Avoid any injury to the bulbospongiosus muscle, the penile bulb, or the membranous urethra. Divide the variably distinct rectourethralis muscle without injury either to the rectal wall or the urethra.

Venous bleeding results from separation of the prostate from the bladder.

Avoid injury to the bladder neck by incising the posterior bladder neck transversely between 5 and 7 o’clock, until the fascia enveloping the seminal vesicles can be identified. Care must be exercised during reconstruction of the bladder neck to avoid injury of the ureteric orifices.

Urinary perineal leakage is a very benign complication, and will heal rapidly. A Foley catheter should be positioned in the most dependent area of the urinary bladder.

In perineal prostatectomy, the complications of stricture at the urethrovesical anastomosis, incontinence, and impotence are similar to the conditions mentioned previously.

Ahearn et al.132 reported two cases of transient lumbosacral polyradiculopathy after radical prostatectomy.

Bulbourethral Glands of William Cowper

History

Table 25-1 presents a historical note about the bulbourethral glands.

Embryogenesis and Congenital Anomalies

The spongy urethra is responsible for the genesis of the urethral and bulbourethral glands.

Congenital anomalies of the bulbourethral glands include syringocele (retention cyst) and diverticulum of the anterior urethra. Syringocele may produce intraurethral urinary retention or incontinence.

Surgical Anatomy

The two round bulbourethral glands have an approximate diameter of 0.5-1.5 cm. They are located within the sphincter urethrae muscle, adjacent to the membranous part of the urethra; therefore, they are below the prostate (see Fig. 25-12). Each gland has a minute duct which penetrates the inferior fascia of the urogenital diaphragm. It enters and traverses the penile substance, ending in the lower aspect of the spongy urethra (bulbous) on either side at 3 and 9 o’clock.

Histology

Each bulbourethral gland is formed by several tubuloalveolar glands with columnar or cuboidal glandular epithelium.

Very rarely, the bulbourethral glands may develop an adenocarcinoma that invades the prostate. According to Hopkins and Grabstald,133 it is possible in most cases to visualize the perineal mass and feel the prostate behind the tumor.

Physiology

The bulbourethral and urethral glands secrete mucus consisting of sialoproteins and amino sugars. This mucus may aid in lubricating the urethra.

Potential Spaces under the Urogenital Diaphragm

Surgical Anatomy

Potential spaces under the urogenital diaphragm include the peripenile space, the periscrotal space, and the superficial perineal cleft.

It is well known that there is a potential space between the superficial fascia and the deep fascia on the anterior abdominal wall. This potential space is continuous superiorly with the retromammary space. It is also continuous inferiorly. Its continuation over the penis and the scrotum could be referred to as the peripenile and periscrotal spaces, respectively. In the perineal area, this potential space is named the superficial perineal cleft (see “Layers of the Scrotum” in this chapter).

The potential space is sealed off from the thighs laterally by the attachment of Colles’ membranous fascia to the ischiopubic rami. It is closed off from the ischioanal fossae posteriorly by the fusion of Colles’ fascia with the posterior edges of the superficial compartment (at the superficial transversus perineus muscle and the perineal body) and the urogenital diaphragm.

The superficial perineal cleft can always be found by blunt dissection, though the distinction between the fascial layers in the perineum may be difficult to visualize clearly. Begin in the perineum and probe upward. Or begin in the space between the superficial and the deep fascia on the anterior abdominal wall and probe inferiorly around the scrotum.

Male Urethra

History

The anatomic and surgical history of the male urethra is shown in Table 25-1.

Embryogenesis

Normal Development

The pelvic part of the urogenital sinus in the male is responsible for the genesis of the prostatic and membranous parts of the urethra.

The endodermal and splanchnic mesoderm participate in the formation of the urethra, the former being responsible for the epithelium and the latter for the connective tissue and smooth muscle.

Congenital Anomalies

Congenital anomalies of the male urethra can be found in Table 25-2.

Atresia and Stenosis

Atresia and stenosis may be caused by failure of the urethral plate to canalize. By definition, the urethral plate is “the endodermal layer of the attenuated distal portion of the urogenital sinus … displayed on the caudal aspect of the phallus… [w]ith proliferation of mesenchyme within the genital folds, the urethral plate sinks into the body of the phallus forming a primary urethral groove,” according to Gray’s Anatomy.134 Meatal stenosis is treated by meatomy. Urethral reconstruction or replacement are the procedures of choice for more extensive atresias.

Duplications of the Penile Urethra

Duplication of the penile urethra is a rare anomaly. One can only speculate about the origin of this malformation. The existence of an extra endodermal canal or closing or splitting of the urethral plate are speculative etiologic factors.

Collateral duplications consist of complete duplication with diphallia and abortive duplication (one urethra is a blind sinus).

Treatment consists of excision of the more atretic accessory channel.

Dislocations of the Penile Urethra

In epispadias, the opening of the urethra is located at the dorsum of the penis. This condition may be caused by a shift of the lateral anlage of the genital tubercle. Epispadias is treated surgically.

In hypospadias, the urethral opening may be on the underside of the penis, on the scrotum, or on the perineum. The urethral canal becomes a gutter secondary to partial or total failure of function of the urethral folds. Surgery is the preferred treatment. A study by Erol et al.135 found that the urethral plate is well vascularized, and has a rich nerve supply and an extensive muscular and connective tissue backing. Based on the findings, they advocate preservation of the urethral plate and the onlay island flap for hypospadias reconstruction.

Surgical Anatomy

Fig. 25-49 will orient the reader to the relationships of the male urethra, which has a length of 8 inches (20 cm).

Fig. 25-49.

Anatomic relationship of bladder, prostate, prostatomembranous urethra, and root of penis. Prostate, situated just below bladder base, has its apex resting on genitourinary diaphragm, within which Cowper’s glands, with ducts extending distally, open into bulbous part of the urethra, surrounded by corpus spongiosum. Two corpora cavernosa diverge at this point, each one gaining fixation to pubic arch. (From Tanagho EA. Anatomy of the lower urinary tract. In: Walsh PC, Retik AB, Stamey TA, Vaughan ED Jr (eds). Campbell’s Urology (6th ed). Philadelphia: WB Saunders, 1992, pp. 40-69; with permission.)

The urethra has 3 relatively narrow areas:

 

at the membranous part of the urethra

at the juncture of the glans penis with the corpus spongiosum

at the external urethral meatus

Topographic Anatomy

Tanagho71 (Fig. 25-50) subdivides the urethra into prostatic, membranous, bulbous, and penile areas.

Fig. 25-50.

Urethral lumen, prostatic urethra, membranous urethra, bulbous urethra, and penile urethra, which opens into external meatus after fusiform dilatation of navicular fossa. (Modified from Tanagho EA. Anatomy of the lower urinary tract. In: Walsh PC, Retik AB, Stamey TA, Vaughan ED Jr (eds). Campbell’s Urology (6th ed). Philadelphia: WB Saunders, 1992, pp. 40-69; with permission.)

Hinman,66 however, considers the prostatic urethra an anatomic entity that belongs to the prostate. He defines the combined membranous-penile urethra to be composed of three segments (Fig. 25-51): bulbomembranous, bulbospongy, and penile. The bulbomembranous urethra is related to the urogenital diaphragm with the striated urethral sphincter and has a length of 2 cm. The bulbospongy urethra extends from within a few centimeters of the anatomic membranous urethra distally to the level of the suspensory ligament. The bulbourethral ducts (Cowper’s) empty into this segment at 3 and 9 o’clock.

Fig. 25-51.

Gross structure of urethra shows bulbomembranous urethra (A), bulbospongy urethra (B), and penile urethra (C), as used by Hinman.66 (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunder, 1993.)

In our discussion below, we will use the following terminology: prostatic urethra (including the preprostatic part), membranous urethra, and spongy or penile urethra, as widely accepted.

Prostatic Urethra

That part of the urethra from the vesical neck to the prostate is referred to as the preprostatic segment. It is 1-1.5 cm long, and has a stellate-shaped lumen. Smooth muscle of this segment of the urethra prevents retrograde ejaculation.

The segment of the prostatic urethra (Fig. 25-52) in the gland above the superior fascia of the urogenital diaphragm traverses the prostatic parenchyma, between the anterior and middle thirds of the gland. The prostatic urethra has a length of approximately 3 cm, and is the widest and most distensible of the segments. Its pathway is not straight, forming an acute angulation at the area of the verumontanum (Fig. 25-52, Fig. 25-53).

Fig. 25-52.

Anterior aspect of the neck of the bladder and posterior aspect of the urethra. Inset shows details of the prostatic urethra. (Modified from McVay CB. Anson & McVay Surgical Anatomy, 6th Ed, Vol II. Philadelphia: WB Saunders, 1984; with permission.)

Fig. 25-53.

Section of the prostate gland shows the prostatic urethra, verumontanum, and crista urethralis, in addition to the opening of the prostatic utricle and the two ejaculatory ducts in the midline. Note that the prostate is surrounded by the prostatic capsule, which is covered by another prostatic sheath derived from the endopelvic fascia. The prostate is resting on the genitourinary diaphragm. (Modified from Tanagho EA. Anatomy of the lower urinary tract. In: Walsh PC, Retik AB, Stamey TA, Vaughan ED Jr (eds). Campbell’s Urology (6th ed). Philadelphia: WB Saunders, 1992, pp. 40-69; with permission.)

The student of urethral anatomy should remember the 3 elevations within the lumen of the prostatic urethra:

 

crista urethralis

verumontanum

prostatic utricle

The crista urethralis (Fig. 25-52) is an elevation of the mucous membrane in the form of a median longitudinal ridge, located posteriorly on cross-section. For all practical purposes, the crista urethralis is the downward continuation of the superficial trigone of the urinary bladder. It bifurcates into the bulbous urethra. The prostatic sinus is located on each side of the crista urethralis. The orifices of the prostatic ducts are found in the floor of the prostatic sinus.71

The verumontanum is an elevation at the middle area of the urethral crest.

The prostatic utricle (utriculus masculinus) and the orifices of the right and left ejaculatory ducts are located upon the summit of the verumontanum.

Membranous Urethra

The membranous urethra is the urethral segment within the urogenital diaphragm. Tanagho71 stated that it is the thickest segment. It is also the narrowest (except for the external urethral meatus), shortest (2-2.5 cm) and least dilatable part of the urethra. The membranous urethra takes a curved pathway forward and downward through the urogenital diaphragm, becoming concave ventrally.

Smooth and striated muscle thickly invests this part of the urethra. The most important muscular component is the striated external coat, which is the voluntary urinary sphincter. The skeletal muscle is supplied by somatic motor fibers (from sacral levels S2-S4) carried by the perineal branch of the pudendal nerve. The muscle forms an incomplete ring at the posterior midline, resembling the Greek letter ‘omega’ (). Therefore, its action is perhaps more compressive than truly sphincteric.

The bifurcation of the crista urethralis extends from the prostatic apex to the penile bulb.

Anteriorly, the deep dorsal vein of the penis enters the pelvis between the arcuate pubic ligament and the transverse perineal ligament.

The right and left bulbourethral glands (Fig. 25-52) are located lateral to the membranous urethra. They drain into the proximal spongy urethra (bulbous). According to Tanagho,71 the cavernous nerves also pass through the diaphragm (at 3 and 9 o’clock) before they penetrate the crura of the penis.

Penile Urethra

The penile urethra is the distal part of the urethra. It extends from the inferior fascia of the urogenital diaphragm to the external meatus of the penis. The proximal segment is called the bulbar part, because it is enveloped by the penile bulb and the bulbospongiosus muscle. The distal part is called the pendulous part of the penile urethra. The penile (or spongy) urethra is located within the corpus spongiosum of the penis (Fig. 25-54). Its pathway is upward and downward as well as downward and forward when the penis is flaccid.

Fig. 25-54.

Cross section of penis, demonstrating the relationship between the corporal bodies, penile fascia, vessels, and nerves. (Modified from Devine CJ Jr, Angermeier KW. The anatomy of stress incontinence. AUA Update Series, 1994; 13(2):10; with permission.)

The lumen of the penile urethra is transversely slitlike until micturition, when it expands to about 6 mm. The adult spongy urethra has an approximate length of 15 cm. It is dilated at its intrabulbar part and distally at the navicular fossa, just internal to the meatus. The external meatus, which is also about 6 mm in length, is sagittal in orientation.

The termination of the urethra is characterized by the fossa navicularis (Fig. 25-52), a widening of the urethral lumen which corresponds to the entrance of the urethra to the glans penis. Its opening at the external meatus is the narrowest part of the entire urethra. A calculus can lodge at this point.

Vascular Supply

Arteries

The arterial supply of the prostatic, membranous, and penile urethra:

 

Prostatic: inferior vesical artery, middle rectal artery

Membranous: artery of bulb (from internal pudendal artery)

Penile: urethral artery, bulbar artery, tiny branches from dorsal and deep arteries of penis

Veins

The veins drain into the prostatic plexus by way of the deep dorsal vein and into the internal pudendal veins by way of the paired dorsal veins.

Lymphatics

The prostatic and membranous lymphatics drain into the internal and external iliac nodes. The spongy lymphatics drain into the deep inguinal lymph nodes, with a minority draining into the external iliac nodes.

Innervation

The possible innervation of the prostatic urethra is by the prostatic plexus. The cavernous nerves from the prostatic plexus innervate the membranous urethra. The penile urethra is innervated by the pudendal nerve.

We quote Strasser and Bartsch136 on the innervation of the rhabdosphincter:

The rhabdosphincter presents as a vertical structure extending from the bulb of the penis to the region of the bladder neck along the prostate and the membranous urethra. Inserting dorsally into the perineal body via a broad tendinous raphe, the striated muscle fibers form an omega-shaped loop around the anterior and lateral aspects of the membranous urethra. The existence of a “urogenital diaphragm” and a strong, circular, striated “external sphincter urethrae” completely encircling the urethra caudal to the apex of the prostate cannot be confirmed by anatomical and histological investigations. The rhabdosphincter is supplied by branches of the pudendal nerve after leaving the pudendal canal.

Histology

The wall of the urethra is formed by 3 layers:

 

muscular coat

mucosal coat

submucosal layer

The muscular coat of the prostatic and membranous urethra is the downward continuation of the detrusor muscle of the urinary bladder. Therefore, it is especially innervated by sympathetic nerve fibers. The sphincter urethra is formed by striated muscle which surrounds the membranous urethra.

After studying 50 male and 15 female cadavers, Rother et al.137 stated that the volume of muscle cells and fibers in male and female urethral sphincter muscles decreases with age, beginning in early childhood.

The mucosal coat is composed proximally of transitional epithelium continuous with that of the bladder. This cell type terminates at the verumontanum, just distal to the openings of the ejaculatory ducts. Distally, a mixture of stratified columnar epithelium and pseudostratified epithelium with mucous glands can be found. The mucous membrane of the penile urethra is characterized by frequent recesses associated with the tubular mucous glands of Littre, particularly in the dorsal part of the urethra. Distally in the penile urethra, the mucosa becomes stratified squamous in character.

The submucosal layer has a rich vascular and erectile network.

Anatomic Complications

If the male urethra is divided by traumatic injury or for clinical reasons, the pathway taken by extravasating urine and blood differs between the anterior (bulbous and pendulous) segments and the posterior (prostatic and membranous) segments, because of the anatomic arrangement of fascial layers and their connections.

If the deep fascial layer is torn from rupture of the anterior urethra, the extravasate can flow into the superficial perineal cleft (see preceding section “Potential Spaces Under the Urogenital Diaphragm” in this chapter). From this space, it can readily track superiorly into the periscrotal and peripenile spaces, and upward upon the abdominal wall, even reaching the level of the nipples. Rupture of the urethra is shown in Figs. 25-55, 25-56, 25-57, and 25-58. Hackler138 stated that Colles’ fascia resists the penetration of urine into the pelvis, the thigh, and the anal triangle.

Fig. 25-55.

A, Rupture of urethra above urogenital diaphragm. B, Rupture of bulbous urethra and muscle fascia (deep perineal fascia) of Gallaudet. Diagonal lines represent extravasation of urine. (Modified from Decker GAG, Du Plessis DJ. Lee McGregor’s Synopsis of Surgical Anatomy (12th ed). Bristol UK: Wright, 1986; with permission.)

Fig. 25-56.

Anterior urethral rupture. Extravasation limited to penile shaft when Gallaudet’s (Buck’s) fascia remains intact. (Based on Hackler RH. Complications of urethral and penile trauma. In: Greenfield LJ (ed). Complications in Surgery and Trauma. Philadelphia: JB Lippincott, 1984, pp. 741-748.)

Fig. 25-57.

Rupture of anterior urethra. Extravasation limited within Buck’s fascia. (From Hackler RH. Complications of urethral and penile trauma. In: Greenfield LJ (ed). Complications in Surgery and Trauma (2nd ed). Philadelphia: JB Lippincott, 1990, pp.784-791; with permission.)

Fig. 25-58.

Disruption of prostatomembranous urethra. Extravasation into retroperitoneal space above the perineal membrane. Note rupture of puboprostatic ligament. (Based on Hackler RH. Complications of urethral and penile trauma. In: Greenfield LJ (ed). Complications in Surgery and Trauma. Philadelphia: JB Lippincott, 1984, pp. 741-748.)

Rupture of the anterior urethra at the junction of the penile bulb and the inferior fascial layer of the urogenital diaphragm (that is, the perineal membrane) results in extravasation of urine and blood. If there is no break in the continuous layer of deep fascia, which includes the perineal fascia of Gallaudet and the penile fascia of Buck, extravasation is limited to the penile shaft (Fig. 25-56).

Rupture of the posterior urethra at the junction of the prostatic apex and the urogenital diaphragm produces an extraperitoneal pelvic collection of urine and blood (Fig. 25-58). We believe that Denonvilliers’ fascia posteriorly and the urogenital diaphragm inferiorly are the anatomic entities responsible for the limits of extravasation in the extraperitoneal area and into the space of Retzius.

According to Hackler,138 pelvic fractures are responsible for 90% of the injuries of the posterior urethra (prostatomembranous), but the injury is significant in only 10% of male patients. Frick et al.139 reported that approximately 13% will also have urinary bladder disruption.

The treatment of urethral injuries depends upon the severity of the injury. Observation, suprapubic cystostomy, or exploration with urethral realignment are the procedures of choice, according to the injury.

Penis

History

The anatomic and surgical history of the penis is shown in Table 25-1.

Embryogenesis

Normal Development

Under the influence of testosterone, the genital tubercle is responsible for the genesis of the penis.

Congenital Anomalies

Congenital anomalies of the penis will be found in Table 25-2. These include agenesis of the glans penis, phimosis, duplication, transposition of the penis and scrotum, and defects of the corpus spongiosum and corpora cavernosa.

Agenesis of the penis may be associated with several other anomalies. The scrotum is normal and the testes may be descended or undescended. The embryogenesis of this malformation may be lack of formation of the genital tubercle, with no pars phallica to the urogenital sinus. Treatment includes reconstruction of the phallus and inflatable penile prosthesis.

Penoscrotal transposition is a rare anomaly with partial or complete positional exchange between the penis and scrotum. It may be associated with severe chordee and hypospadias.140

Surgical Anatomy

Topographic Anatomy

Structure

The penis can be divided into three parts: the root, the body, and the glans. The root, or penile bulb, is located within the superficial perineal pouch. According to Tanagho,71 it provides fixation and stability. The body is formed by the three spongy erectile anatomic entities: two corpora cavernosa and one corpus spongiosum. The glans is the distal end of the corpus spongiosum.

The paired corpora cavernosa are located on the dorsum of the pendulous part of the penis, partially separated by the penile septum. Proximally, each begins as a slender cylinder firmly attached to the ischiopubic ramus. From this origin to the pendulous part of the shaft, each of the two erectile bodies is referred to as a crus penis; the continuation is the corpus. The penile crus is surrounded by fibers of the ischiocavernosus muscle, stoutly attached to the ischiopubic ramus and the perineal membrane (Fig. 25-59).

Fig. 25-59.

Corpora cavernosa and crus penis. Parasagittal section of the perineum. (Based on O’Rahilly R. Gardner-Gray-O’Rahilly Anatomy (5th ed). Philadelphia: WB Saunders, 1986.)

The corpus spongiosum, or penile bulb, lies in the ventral midline area of the penis (Fig. 25-60). Its proximal part is covered by the bilateral bulbospongiosus muscles (Fig. 25-61). After taking origin from the perineal membrane and the perineal body, the muscle fibers pass anteromedially, inserting into the midline penile raphe. The corpus spongiosum surrounds the urethra, which is open at the end of the glans. The bulbospongiosus muscles and ischiocavernosus muscles are covered externally by a very distinct muscle fascia, the fascia of Gallaudet. This fascial layer is continuous from the crura to the bulb, and also attaches deeply to the perineal membrane.

Fig. 25-60.

Structural layers of penis. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-61.

Bulbospongiosus and ischiocavernosus muscles cover corpora cavernosa and corpus spongiosum.

Ligaments

The penis is supported by two ligaments, the fundiform and the suspensory. The fundiform ligament is a downward continuation of the superficial fasciae of Camper and Scarpa, which lose their individual identity as they merge to form the fundiform ligament (see “Potential Spaces Above the Urogenital Diaphragm” in this chapter). When approaching the penile dorsum, it splits, surrounds the body of the penis, and unites at the penile ventral area with the scrotal septum. The suspensory ligament under and deep to the fundiform ligament arises from the fascia of Gallaudet (deep fascia of the abdominal wall) and from the frontal aspect of the pubic bone and the symphysis, blending below with the deep penile fascia on each side.

Hoznek et al.141 stated that the anatomy of the suspensory ligament of the penis consists of separate ligamentous structures, as follows:

The suspensory apparatus consisted of separate ligamentous structures: the fundiform ligament, which is lateral, superficial and not adherent to the tunica albuginea of the corpora cavernosa; the suspensory ligament properly so-called, further back, stretching between the pubis and the tunica albuginea of the corpora cavernosa and consisting of two lateral, circumferential, and one median bundles, which circumscribed the dorsal vein of the penis. These structures were identifiable in MRI and their supporting role was evidenced during tests of erection. The suspensory ligament seemed to maintain the base of the penis in front of the pubis and to behave as a major point of support for the mobile portion of the penis during erection.

Penile Coverings

From superficial to deep, the penile coverings are: the skin, the superficial fascia, the tela subfascialis, the deep fascia (Buck’s), and the tunica albuginea (Fig. 25-60, Fig. 25-62). These structures cover the shaft of the penis and, therefore, the three erectile, cylindrical, tubelike entities (two corpora cavernosa and one corpus spongiosum).

Fig. 25-62.

A, Cross-section of penis. B, Arterial and venous supply. (Modified from Siegel SW. Anatomy and embryology. In: Novick AC (ed). Stewart’s Operative Urology, 2nd ed. Baltimore: Williams & Wilkins, 1989, pp. 454-478; with permission.)

The skin that covers the penis is thin, with a very thin areolar layer which covers, or is mixed with, the superficial penile fascia. The distal part of the skin forms two anatomic entities, the foreskin (prepuce) and the frenulum. The prepuce or foreskin is a fold of skin at the area of the penile neck. The frenulum is a narrow, midline ridge of redundant skin on the ventrum of the shaft which extends from the meatal groove to the coronal sulcus.

The superficial penile fascia is the downward continuation of the fasciae of Camper and Scarpa. It is without an adipose content, but with some smooth muscle fibers, like the dartos tunic of the scrotum.

Occasionally, the superficial fascia is called Colles’ fascia in the literature. However, we like to reserve this eponym for the part of the fascia of Scarpa that continues immediately after the formation of the tunica dartos, and that terminates by fusing posteriorly with the urogenital diaphragm. Colles’ fascia, therefore, participates in the formation of the superficial perineal cleft. Several authors also name the superficial pouch as the pouch of Colles.142

The tela subfascialis a very thin areolar tissue layer. It occupies the interval between the superficial dartos tunic and Buck’s deep fascia over the extracorporal segments of the cavernous arteries, veins, and nerves.66 Also in this interval are the bilateral dorsal arteries, dorsal veins, and dorsal nerves.

The deep penile fascia (fascia of Buck) covers the corpora cavernosa and the corpus spongiosum. Buck’s fascia splits to invest the deep dorsal vein in the midline of the penile shaft.

The tunica albuginea is a thick white connective tissue matrix formed by two fibrous layers, the outer longitudinal and the inner circular, with little in the way of elastic tissue. It is strongly attached to the overlying fascia of Buck; or perhaps it is better to say that the fascia of Buck is firmly fixed to the tunica albuginea.

Vascular Supply

Arteries

The arterial blood supply of the penis is formed by a superficial and a deep system (Fig. 25-62B). The external pudendal artery is responsible for the formation of the superficial system; the internal pudendal artery provides the deep system.

Superficial System

The arterial blood supply of the skin of the penis is very good. It originates from the external pudendal artery (from the common femoral artery), which gives origin to a dorsolateral and a ventrolateral branch (Fig. 25-63).

Fig. 25-63.

Superficial arterial system. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Deep System

The internal pudendal arteries, right and left, give origin to the penile artery. The penile artery gives three or four bilateral branches to the penis: the bulbourethral artery (the artery to the bulb and the urethral artery), the deep artery (central or cavernous), and the dorsal artery. Figure 25-64 summarizes both the superficial and deep systems.

Fig. 25-64.

Arteries of the penis.

The bulbourethral artery and the deep artery arise within the urogenital diaphragm. There are good anastomoses between the deep artery and the bulbourethral artery, but not between the deep and dorsal arteries.

The dorsal artery can be regarded as the terminal continuation of the internal pudendal artery (Fig. 25-65). The dorsal artery leaves the urogenital diaphragm by piercing the transverse perineal ligament (the fusion of the superior and inferior fasciae of the diaphragm) and by passing onto the dorsum of the shaft beneath the superficial fascia.

Fig. 25-65.

Vasculature of penis. (Modified from Redman JF. Anatomy of the genitourinary system. In: Gillenwater JY, Grayhack JT, Howards SS, Duckett JW (eds). Adult and Pediatric Urology, 2nd ed. St. Louis: Mosby Year Book, 1991, pp. 3-62; with permission.)

The beneficiaries of the dorsal artery are the corpora cavernosa, the corpus spongiosum, the tunica albuginea, and the urethra which are pierced by branches of the dorsal artery. The dorsal artery also gives off laterally directed circumflex branches which pass to the corpus spongiosum, with similarly named tributaries to the deep dorsal vein. The fellow traveler with the dorsal artery is the more laterally situated dorsal nerve.

According to Gardner et al.,143 the dorsal artery provides most of the blood supply to the glans. Remember that the dorsal arteries and nerves curve ventrally before entering the glans (Fig. 25-66). The dorsal artery terminates as the artery to the glans.

Fig. 25-66.

Blood supply to glans and frenulum. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

The bilateral deep artery of the penis (cavernous) enters each corpus cavernosum on the deep surface of the crus and continues its pathway toward the glans (Fig. 25-67). However, its branches terminate approximately at the penile neck without anastomosing with the branches of the dorsal artery.

Fig. 25-67.

Distal arterial distribution to penis. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

NOTE: The bulbourethral artery is presented in some anatomy books as the bulbar and urethral arteries (Fig 25-65), and in others as a a single artery (Fig. 25-67).

The bulbourethral artery is often short and wide. It enters the bulb of the penis after piercing the inferior fascia of the urogenital diaphragm. This artery supplies the bulb, the urethra, the corpus spongiosum and the glans. It may arise from the bulbar artery.

Droupy et al.144 described three patterns of penile arterial supply based on dissection of twenty fresh cadavers.

 

Type I arises from the internal pudendal arteries (3 of 20)

Type II arises from both accessory and internal pudendal arteries (14 of 20)

Type III arises from accessory pudendal arteries (3 of 20)

Veins

The veins of the penis form a very peculiar and enigmatic system. The heterogeneity and complexity of this system approaches that of the human venous system as a whole. Moscovici et al.145 studied the venous vasculature of 25 cadaveric penises and reported as follows:

The superficial veins arising from the tegumentary layers drain into the superficial dorsal vein which in three-quarters of cases empties into the left great saphenous vein. The veins of the deep internal system, running below the deep fascia of the penis, emerge from the erective bodies and can be divided into two systems, one anterosuperior and the other posteroinferior. The anterosuperior system comprises the veins of the glans which will form the deep dorsal vein; the latter receives blood from the medial portion of the the corpus spongiosum and from the free portion of the corpora cavernosum mainly via the circumflex veins. It ends in the pre-prostatic plexus. The posteroinferior system, issuing from the posterior portion of the erectile bodies, is composed of the bulbar, cavernous and crural veins which drain towards the pre-prostatic plexus and the internal pudendal veins. Anastomoses link the two networks, superficial and deep. Study of the structure of the veins of the deep system reveals the presence of muscular cushions, which we have shown to have adrenergic innervation. (Fig. 25-68, Fig. 25-69, Fig. 25-70, Fig. 25-71)

Fig. 25-68.

Dorsal view of the penis after injection-corrosion showing the veins of the glans, the retrocoronal plexus and the deep dorsal vein. (From Moscovici J, Galinier P, Hammoudi S, Lefebvre D, Juricic M, Vaysse P. Contribution to the study of the venous vasculature of the penis. Surg Radiol Anat 1999;21:193-199; with permission.)

Fig. 25-69.

Dorsal view of a dissection revealing two dorsal veins of unequal calibre. (From Moscovici J, Galinier P, Hammoudi S, Lefebvre D, Juricic M, Vaysse P. Contribution to the study of the venous vasculature of the penis. Surg Radiol Anat 1999;21:193-199; with permission.)

Fig. 25-70.

Ventral view of the penis after injection-corrosion showing the inferior emissary veins and the origin of the circumflex veins. (From Moscovici J, Galinier P, Hammoudi S, Lefebvre D, Juricic M, Vaysse P. Contribution to the study of the venous vasculature of the penis. Surg Radiol Anat 1999;21:193-199; with permission.)

Fig. 25-71.

The two drainage systems of the erectile bodies: the anterosuperior system comprising the veins of the glans, the retrocoronal plexus (RCP), the circumflex veins (CiV) and the deep dorsal vein (DDV); and the posteroinferior system comprising the bulbar (BV), cavernous (CaV), and crural (CrV) veins. (Modified from Moscovici J, Galinier P, Hammoudi S, Lefebvre D, Juricic M, Vaysse P. Contribution to the study of the venous vasculature of the penis. Surg Radiol Anat 1999;21:193-199; with permission.)

. . .The blockage of the anterosuperior system during erection by the deep fascia of the penis and possibly by vasomotor changes involving polsters could play a role in maintaining erection. However, its main mechanism remains the compression of the sub-albugineal venous plexus inside the cavernous bodies. The posteroinferior system could be a preferential route for nutritive drainage of the penis.

An excellent presentation of the penile veins is given by Hinman.66 He divides the penile venous network into three systems: superficial, intermediate, and deep (Fig. 25-72).

Fig. 25-72.

Three drainage systems of penis: superficial, intermediate, and deep. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Superficial System

The superficial dorsal vein is the major component of the superficial (subcuticular) venous penile network. The superficial dorsal vein, which is rarely double, is formed from several minute veins of the dorsolateral penile surface. The superficial venous system drains the penile skin.

Intermediate System

The intermediate system is formed by the following entities.

 

Deep dorsal vein

Circumflex vein

Prostatic plexus

Lateral venous plexus

Retrocoronal plexus

These multiple veins are located under Buck’s fascia. They drain the glans penis, corpus spongiosum, and distal two-thirds of the corpora cavernosa. The intermediate system drains into the deep dorsal vein or veins, which terminates into the internal iliac veins via the prostatic and vesical plexuses.

Topographicoanatomically the deep dorsal vein, invested by Buck’s fascia, is disposed between the bilateral lymphatics, the dorsal artery, and the dorsal nerve. Small veins leave the deep dorsal vein before its passage into the pelvis to drain into the internal pudendal vein. Passing through the perineum, the internal pudendal veins receive tributaries from the penile bulb and from the scrotum.

The deep dorsal vein is located between the two corpora cavernosa. It receives much of their venous drainage by way of deep perforating vessels. These vessels arise from minute tributaries of the corpus spongiosum, the adjacent corpora cavernosa, and the circumflex veins from the corpus spongiosum (Fig. 25-73). The perineal and penile veins are valveless.

Fig. 25-73.

Blood vessels and nerves of penile shaft (cross section). (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Deep System

The deep system drains into the deep dorsal vein which goes to the internal pudendal vein. It is formed by the following veins.

 

Cavernous

Bulbar

Crural

We refer the student who wants to know more about the complicated relations of the deep system to the excellent book of Hinman.66

Lymphatics

The lymphatic drainage of the penis is peculiar. The skin and prepuce drain into the superficial inguinal lymph nodes (Fig. 25-74). The lymphatics of the glans and penile urethra drain into the deep inguinal and external iliac lymph nodes (Fig. 25-75).

Fig. 25-74.

Superficial lymph drainage system. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Fig. 25-75.

Deep inguinal drainage system. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Innervation

Somatic

The dorsal nerves originate from the pudendal nerve within Alcock’s canal (Fig. 25-76). They enter the dorsum of the penis to innervate the skin and glans of the penis. The perineal nerves and their branches innervate the vessels of the erectile elements and the urethra. The sensory fibers enter the dorsal gray of the cord at cord levels S2-S4. Likewise, the motor supply to the ischiocavernosus and bulbospongiosus muscles is supplied by motor fibers from the ventral gray area at the same cord levels. The ilioinguinal nerve innervates the skin of the root of the penis.

Fig. 25-76.

Somatic innervation of penis. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

The dissection studies of Colombel et al.146 showed evidence of communication between the cavernous nerves and the dorsal nerve of the penis.

Autonomic

The sympathetic nerves arise from spinal cord levels L1 and L2, synapsing in the sympathetic chains at vertebral levels S2, S3, and S4. The postganglionic fibers join the sacral nerves and pass into the pudendal nerve. These nerve fibers are responsible for vasoconstriction. According to Andersson et al.,147 they produce erection through a series of complex interactions. Stimulation of the sympathetic pathways also mediates detumescence and contributes to the maintenance of the penis in a non-erect state.

The parasympathetic nerves from S2, S3, and S4 (the nervi erigentes) produce vasodilation and resultant erection. The cavernous nerve originates from the prostatic plexus and supplies the corpus cavernosum (Fig. 25-77). Occasionally, it bifurcates. One branch is responsible for the erectile tissue of the corpus spongiosum and the penile urethra. The other branch is responsible for the erectile tissue of the corpora cavernosa.

Fig. 25-77.

Autonomic innervation of penis. (Based on Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993.)

Remember

 

The terminology for the nerve plexuses in the lower abdomen and pelvis is inconsistent and confusing. In this regard, one hears of superior and inferior mesenteric plexuses, preaortic plexuses, superior and inferior hypogastric plexuses, and so on. There is little doubt that many of the terms, such as “hypogastric,” are outdated. It would perhaps be simpler to refer to a preaortic plexus that bifurcates into right and left pelvic plexuses. These, in turn, would give rise to more precisely named entities, such as the vesical plexus, the prostatic plexus, and so on. However, the prostatic plexus is formed by the inferior hypogastric plexus (autonomic) which is responsible for the genesis of the cavernous nerve (a forward continuation of the prostatic plexus).

The inferior hypogastric plexus is synonymous with the pelvic plexus. It is located on the lateral pelvic wall (Fig. 25-78). It is formed by:

 

– postganglionic sympathetic nerves that have descended through the hypogastric plexus from ganglia in the lumbar part of the sympathetic chains

– preganglionic parasympathetic fibers that arise directly from the ventral rami of S2-S4 as pelvic splanchnic nerves

– sensory fibers for pain and other modalities from the pelvic organs

Fig. 25-78.

Nerves of posterior abdominal wall. 1, Celiac ganglia. 2, Cardia of stomach. 3, Subcostal nerve. 4, Transversus abdominis. 5, Iliohypogastric nerve. 6, Genitofemoral nerve. 7, Ilioinguinal nerve. 8, Testicular artery (unusual origin from renal artery). 9, Femoral nerve. 10, Lateral cutaneous nerve of thigh. 11, Inferior hypogastric (pelvic) plexus. 12, Obturator nerve. 13, Ductus deferens. 14, Ilioinguinal nerve. 15, Nervi erigentes. 16, Superior hypogastric plexus. 17, Testicular vessels. 18, Internal oblique muscle. (From Last RJ. Anatomy Regional and Applied (5th ed). Baltimore: Williams & Wilkins, 1972; with permission.)

 

The nervi erigentes from S2-S4 are responsible for general sensations from the left colon and the pelvic organs. Parasympathetic functions include the sense of distention and reflex behavior for emptying of the urinary bladder and rectum. Pain from the epididymis is also carried by these nerves.

Pain fibers from visceral structures are usually carried by nerves which are principally associated with the sympathetic nervous system; this is obviously a primary protective feature of the “fight or flight” function of that system. Pain from the urinary bladder passes upward through the hypogastric plexus. Passing into the sympathetic chains by way of the sacral and lumbar splanchnic nerves, these pain fibers then ascend in the chains to spinal cord levels T10-L2, where they gain access to the spinal cord. It is for this reason that lumbar sympathectomy can alleviate pain from the uterus and certain other pelvic tissues. However, the innervation of the pelvic organs does not enjoy complete unanimity among those who study the neurophysiology in this area.

Initially, the penile neurovascular bundle is located posterolateral to the prostate and anterior to Denonvilliers’ fascia, together with branches of the prostatovesicular artery and veins. To be more specific concerning penile surgery, the neurovascular bundle is located between Buck’s fascia above and the tunica albuginea below. It can be uncovered by an incision lateral to the midline.

Below we reprint a very interesting exchange between investigators of penile innervation. The subject under consideration is the anatomy of the lateral rectal ligaments, anatomic entities related to the pelvirectal spaces above the levator ani which divide the spaces into anterior and posterior compartments. Rutegård et al.148 stated:

The contents of the so-called lateral rectal ligaments are defined differently in surgical and anatomical texts. In surgical texts the middle rectal arteries are referred to as the main structures within them.149-151 In contrast, the meticulous anatomical work by Sato and Sato152 has shown that arteries are found in only about 20 per cent of cadaver dissections, whereas nerve branches from the pelvic plexuses, also called the neurovascular bundles, are uniformly constant structures within the ligaments. This view of the lateral ligaments as important nerve-containing structures is supported by clinicophysiological results after sphincter-saving surgery reported in the Japanese literature.153,154

The autonomic nerve supply of the lower rectum has been postulated to arise from the pelvic side wall plexuses.152,155 The close relationship of the ligaments to the pelvic plexuses, which contain merging sympathetic and parasympathetic nerve fibres, makes the dissection of the ligaments crucial in maintaining genitourinary function.156,157

However, Enker et al.158 recently considered the ligaments to be structures that are surgically developed by medial traction during operation. This view has been further established by the same group after cadaveric studies.159

In disagreement with the hypothesis of Enker et al.,158 Rutegård et al.148 continued:

In fact, the lateral ligaments encountered in rectal surgery correspond well to the medial portion of the lateral ligaments of the rectum as described by Sato and Sato.152 Accordingly, the authors consider the ligaments to be real anatomical findings and not merely surgically developed structures, as recently described.158,159

Rutegård et al.148 show the right lateral rectal ligament in a highly diagrammatic fashion in Fig. 25-79.

Fig. 25-79.

Diagram of the autonomic nerve supply in the pelvis. Surgeon’s view from the head end of the patient. Within the dashed circle, notice that two nerve fibers in the right lateral rectal ligament are divided as they bridge over from the pelvic plexus to the rectum. (Modified from Rutegård J, Sandzén B, Stenling R, Wiig J, Heald RJ. Lateral rectal ligaments contain important nerves. Br J Surg 84:1544-1545, 1997; with permission.)

Liang et al.160 responded to the findings of Rutegård et al.148 as follows:

We endorse the presence of the lateral ligament demonstrated by Rutegård et al. (Br J Surg 1997;84: 1544-5). The lateral ligaments are closely interrelated to the pelvic plexus which is a fenestrated rectangular plate of sympathetic and parasympathetic fibres. This provides innervation to the bladder, ureter, prostate, seminal vesicles, membranous urethra and corpora cavernosa via anterolateral branches, and to the distal rectum via medial branches.161 Conceivably, the nerve fibres elegantly illustrated by the authors by immunohistochemistry were the rectal branches of the pelvic plexus. It is only the medial segment of the lateral ligament that is included in the resection during rectal cancer surgery.152 Before sharp dissection of the lateral ligament we routinely find the location of the plexus by tracing the exposed hypogastric nerve or direct palpation. The pelvic plexus is, therefore, rarely injured during the division of the lateral ligament. Partial injury of the pelvic plexus results in temporary loss of genitourinary function.

The periprostatic plexus represents a further chal-lenge for the colorectal surgeons endeavouring to per-form autonomic nerve-preserving lower rectal cancer surgery. The periprostate plexus, running between the anterolateral rectal wall and the prostate, is vulnerable to inadvertent dissection which results in sexual dysfunction.162

Whether the middle rectal artery is included in the lateral ligament or not is of little clinical significance because its small size allows easy control by cautery.

In the same journal, Rutegård’s reply was as follows:

We appreciate the comments from Liang et al. and agree with their description of the nerve anatomy. Their illustration [Editors’ note: We have not reproduced the illustration in this chapter] has the advantage of clearly showing the sympathetic trunk which can often be visualized even in the presacral area but may give rise to the misunderstanding that the hypogastric nerves and the pelvic plexuses lie close to the rectal wall; in fact they can usually be found on the pelvic side wall.

 

Finally, we quote the cadaveric studies of penile innervation and vascularization by Benoit et al.163:

The pelvic nerve plexus had both parasympathetic and sympathetic roots. It was distributed to the external urethral sphincter giving rise to cavernous nerves which anastomosed in 70% of the cases with the pudendal nerve in the penile root. Accessory pudendal arteries were present in the pelvis in 70% of the cases, anastomosing in 70% of the cases with the cavernous arteries that originated from the pudendal arteries. Transalbugineal anastomoses were always seen between the cavernous artery and the spongiosal arterial network. There were 2 venous pathways, 1 in the pelvis and 1 in the perineum with a common origin from the deep dorsal penile vein. It is concluded that there are two neurovascular pathways destined for the penis that are topographically distinct. One is located in the pelvis and the other in the perineum. We were unable to determine the functional balance between these two anastomosing pathways but experimental data have shown that they are both involved in penile erection. These 2 neurovascular pathways, above and below the levator ani, together with their anastomoses, form a neurovascular loop around the levator ani.

Histology

Both dorsally located corpora cavernosa are covered partially by tunica albuginea; also, the tunica albuginea completely envelops the ventrally located corpus spongiosum of the urethra. All three cylindrical masses are composed of dilated blood vessels lined by epithelium.

Physiology

The anatomy and physiology of erection is beautifully presented in Table 25-8, which describes the blood circulation during tumescence and detumescence. In brief, in response to psychic and tactile stimuli, parasympathetic fibers act to cause vasodilation of the arterial branches supplying the spongy tissues of the corpora cavernosa and the corpus spongiosum, resulting in profuse inflow of blood to them. The relatively inelastic tunica albuginea impedes venous return as the erectile tissue becomes engorged with blood. Contraction of the overlying skeletal musculature is also a part of these processes.

Table 25-8. Blood Circulation during Erection and Detumescence

Arterial Supply  Venous Drainage 
Tumescence Detumescence
Corpora Cavernosa 
Principal cavernous arteries (accessory cavernous arteries) to (dorsal arteries) to helicine arteries to sinusoids 1. Emissary veins to circumflex veins to deep dorsal vein to periprostatic plexus
2. Cavernous vein to internal pudendal vein
3. Crural vein to internal pudendal vein
Corpus Spongiosum 
Bulbourethral arteries to urethral arteries to circumflex branches of dorsal arteries Vein of the bulb to periprostatic plexus to internal pudendal vein
Glans 
Dorsal artery to urethral artery Retrocoronal venous plexus to deep dorsal vein to periprostatic plexus

Source: Hinman F Jr. Atlas of Urosurgical Anatomy. Philadelphia: WB Saunders, 1993; with permission.

Erection of the penis occurs as the cavernous bodies become rigid. The tunica of the corpus spongiosum is not as dense or inelastic as the corpora cavernosa. The tunica of the corpus spongiosum and the terminal glans do not become so turgid as to impede the ejaculate. Following ejaculation, an act principally under sympathetic control, sympathetic domination causes vasoconstriction and detumescence.

Surgical Applications

The following are the most common surgical procedures of the penis:

 

Dorsal slit

Circumcision

Release of chordee

Hypospadias repair

Epispadias repair

Partial penectomy

Total penectomy

Insertion of penile prosthesis

Correction of penile curvature

Excision and incision of Peyronie’s disease

Surgical procedures for priapism

Surgery for penile trauma

Penile replantation

Penile reconstruction

Anatomic Complications

Complications of penile surgery can be avoided by good anatomic knowledge. The most important anatomic complications are injury of the urethra, which was described previously in the section on the male urethra, and bleeding.

Bleeding is avoided by good ligation of the vascular network (superficial dorsal veins, deep dorsal vein, two dorsal arteries). Be sure to ligate the frenulum above its division. This will ligate the frenular branch of the artery to the glans, which originates from the dorsal artery of the penis.

Also presented here are anatomic complications of circumcision in adults and of the amputated penis.

Circumcision in adults consists of partial removal of the excess foreskin of the penis. Bleeding, with hematoma formation, is the most frequent complication of this simple operation. A number of iatrogenic complications have been reported:

 

Removal of too much or too little skin

Amputation of the glans

Skin pathology, such as adhesions, epidermal inclusion cysts, and trapped deposits of smegma. The latter is the result of a bad suture line that does not approximate the mucosal and cutaneous edges.

Laumann et al.164 reported the following:

[C]ircumcision provides no discernible prophylactic benefit and may in fact increase the likelihood of STD [sexually transmitted disease] contraction . . .circum-cised men have a slightly lessened risk of experiencing sexual dysfunction, especially among older men . . .cir-cumcised men displayed greater rates of experience of various sexual practices. While evidence regarding STD experience contributes to ongoing debates, our results concerning sexual dysfunction and practice represent largely unprecedented effects. These findings suggest the need for continued research that should further aid parents in weighing the benefits and risks of circumcising their sons.

 Read an Editorial Comment

For the survival of an amputated penis, microsurgery must be performed. Hackler138 recommended anastomosis of at least one of the dorsal arteries, the deep dorsal vein, and the superficial dorsal vein. Necrosis of the penile skin should be treated by total distal excision to 0.5 cm from the glans penis, and graft of split-thickness skin from the defect to the coronal sulcus. According to Peters and Sagalowsky,166 this will avoid the production of lymphedema.

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