There are three germinal components in the embryo, the endoderm, ectoderm, and mesoderm. Most structures within the GU system arise from the mesoderm. These include the nephric system, the Müllerian and Wolffian ducts, and the gonads. However, the external genitalia is formed from the ectodermal layer. The endoderm forms the cloaca and membrane. In general terms, the ectoderm gives rise to the nervous system and skin, the mesoderm gives rise to muscle and other connective tissues, while the endoderm gives rise to the digestive system and other internal organs. Embryological knowledge helps to explain and understand congenital abnormalities of the GU system.1,2
2. Sadler TW, ed. Langman’s Medical Embryology. 13th ed. Philadelphia: Wolters Kluwer Health; 2014 A developing fetus has the ability to develop into male or female and the default differentiation is female (not male) unless this process is interrupted. Male and female differentiation begins at week 6 in the first (not second) trimester. At this point, all fetuses have the precursors for both male and female differentiation. These are the mesonephric (Wolffian) and paramesonephric (Müllerian) ducts that develop into male and female reproductive structures, respectively. The differentiation into a male is influenced by Müllerian inhibiting substance (MIS) which is produced by (and not acts on) Sertoli cells. This substance causes paramesonephric duct regression. A testosterone analog is produced by the interstitial cells of Leydig, which serves to stimulate masculine development of the mesonephric ducts which then form the epididymis, vas deferens, and seminal vesicles. In the absence of MIS, the paramesonephric ducts develop into the upper vagina, fallopian tubes, and uterus.1,2
correct? Mayer-Rokitansky-Küster-Hauser syndrome is a condition of vaginal agenesis, with or without an absent uterus. Although it is a rare condition, incidence varies from 1:4000 to 1:80,000. It is not caused by a congenital absence of the mesonephric duct. It may be caused by either a defect in the paramesonephric duct or fusion of the urogenital sinus with the paramesonephric duct. Associated urinary abnormalities such as ectopy, duplication, and agenesis occur in 25–50%, but not all patients. The clinical findings are of two types: a genetic female with or without a functioning uterus and absent vagina, who is otherwise normal; or a genetic female with or without a functioning uterus and absent vagina, who also has associated skeletal, urinary, or digestive system anomalies.1–3
Several reconstructive options are available for vaginal agenesis. Málaga technique uses vulvoperineal fasciocutaneous flaps, whereas a McIndoe procedure involves a skin graft after dissection of a tunnel in the perineum, between the rectum and the bladder. This is associated with subsequent stricture and fistula formation. Vascularized bowel can be used to reconstruct the vagina but is associated with excessive mucus secretion and bleeding during intercourse. Other flaps have been described, including rectus abdominis, gracilis, and pudendal thigh flaps.1–3 The Vecchietti procedure is performed laparoscopically and uses traction sutures to help form a neovagina.4 The Davydov procedure combines transabdominal and transperineal approaches to dissect space between the bladder and rectum which is lined with peritoneal flaps to avoid skin grafts.5 Vaginal agenesis can be associated with other anomalies, including imperforate hymen, double vagina, and an introitus obstruction. These can be treated surgically. An imperforate hymen can be treated with perforation and oversewing of the edges. A double vagina can be treated with a transverse incision of the septum. An obstructed introitus can be treated with a vaginoplasty. Frank’s technique is a nonsurgical serial dilation procedure.1–5
5. Takahashi K, Nakamura E, Suzuki S, et al. Laparoscopic Davydov procedure for the creation of a neovagina in patients with Mayer-Rokitansky-Kuster-Hauser syndrome: analysis of 7 cases. Tokai J Exp Clin Med 2016;41(2):81–87 The Cordeiro classification1 considers two main features of the vaginal defect: the location (e.g., anterior, posterior, or lateral wall) and the extent of the defect (for example, partial or circumferential defect). The actual size, cause, infection risk, and chronicity are not considered. The classification is as follows (Fig. 65.1): Type IA: Partial defect involving the anterior or lateral wall Type IIA: Circumferential defect involving the upper two-thirds Type IB: Partial defect involving the posterior wall Type IIB: Circumferential total defect Fig. 65.1 Classification system and algorithm proposed by Cordeiro based on anatomic location. Partial defects (type I) Anterior and/or lateral wall (type IA) Modified Singapore flap Rectusab dominis flap Rolled rectusab dominis flap Bilateral gracilis myocutaneous flaps Posterior wall (type IB) Upper twothirds (type IIA) Total (type IIB) Exceptions to theuse of this algorithm • Morbid obesity • Elderly • Significant comorbidities Circumferential defects (type II)
Vaginal and vulvar defects most commonly occur following oncologic resection, but may also be secondary to radiation therapy, infection, and trauma. Cordeiro has proposed a treatment algorithm in keeping with the classification system for vaginal wall defects. Partial defects (Type I) as in this case are either reconstructed with a modified Singapore flap, if they are anterior or lateral, or a rectus abdominis flap, if they are posterior.1 The Singapore flap is a really useful and reliable flap for reconstruction of partial defects of the vagina. It is a fasciocutaneous flap based on the posterior labial arteries. The flap is designed running parallel to the medial thigh crease and raised deep-to-deep fascia from anterior to posterior. The flap can then be tunneled subcutaneously under the labia to be inset into the vaginal vault. The donor defect can be closed directly within the thigh crease with minimal cosmetic consequence. Although not part of the Cordeiro algorithm for partial posterior defects, the modified Singapore flap can be reliably used for these defects too. In larger defects, bilateral Singapore flaps may be combined.2,3 Circumferential defects can be reconstructed using a rolled rectus abdominis flap, if the upper two-thirds are involved, or bilateral gracilis flaps if the defect is total (see Fig. 65.1).4
Hypospadias is a congenital abnormality of the male urogenital tract that occurs in 1:150 to 1:300 males. It involves a proximally based ventral meatus (occurring anywhere between the glans and perineum), a hooded prepuce, and chordee, which may cause a ventral curvature of the penis. Hypospadias can be subdivided based on the meatal position into proximal, middle, or distal third subtypes. Distal are most common (50%), and proximal are least common (20%). Treatment is surgical and is usually performed between 6 and 9 months of age.1,2
Hypospadias surgery has several goals.1 They include release of the chordee to straighten the penis, creation of a new urethra, and advancement of the urethral meatus to the correct anatomic position. Correction of these abnormalities should improve both function and cosmesis of the penis. A number of techniques are currently used. The most common are the single-stage tubular incised plate (TIP) procedure popularized by Snodgrass2 and the two-stage, full-thickness graft technique described by Bracka.3 The meatal advancement and glanuloplasty (MAGPI) technique is indicated for coronal and glanular variants and involves a vertical incision in the transverse mucosal bar distal to the meatal opening, which is closed transversely. A glanuloplasty is achieved by midline approximation of the lateral glans wings. This technique does not treat chordee. In the TIP procedure a longitudinal incision is made through the midline epithelium of the urethral plate, extending from the hypospadias meatus to the end of the glans. The plate is then tubularized on itself, and the dorsal prepuce is mobilized and used to cover the urethroplasty. Mathieu4 described the flip-flap technique, which transposes the proximal soft tissues over the urethral defect. Duckett5 described the preputial flap. This involves an island flap from the prepuce to the ventral surface of the penis that is used as a tube for the urethra. The Cantwell-Ramsey, Young, and W-flap techniques are used for the correction of epispadias rather than hypospadias.
Epispadias is a severe congenital anomaly involving the penis, which is typically short, wide, and stubby with clefting and flattening of the glans and a dorsally placed urethral meatus. The penis usually has a dorsal curvature. It usually occurs in conjunction with bladder exstrophy, but the other abnormalities listed are not specifically associated with this condition. Epispadias occurs in 1 in 30,000 males (compared with 1 in 350 for hypospadias). Principles of reconstruction are similar in each condition but with specific techniques described for epispadias.1,2
Peyronie’s disease is a fibroproliferative condition of unknown cause that affects the penile shaft. It results in abnormal curvature and painful erections and affects approximately 1 in 100 men between 40 and 60 years of age. Although plication techniques are regularly used, they tend to leave a 20% reduction in erect length, which can be unacceptable to men whose penis was short preoperatively.1–3
Peyronie’s disease is a localized penile disorder of collagen primarily involving the tunica albuginea. The penis has a number of key layers. From superficial to deep, these are the skin, Dartos fascia, and then Buck’s fascia. The tunica albuginea lies deeper still and surrounds each corpus cavernosa which are the erectile components of the penile shaft. The deep arteries lie within this tissue. There are two dorsal veins, one deep to skin and the other deep to the deep fascia (Buck’s). The dorsal arteries and nerves are also found in this layer. The urethra is located in the midline and is covered by the corpus spongiosum which is also covered by deep fascia (Buck’s). Knowledge of these layers is important in penile surgery and understanding techniques for hypospadias, epispadias, and Peyronie’s disease. About 10% of patients also have Dupuytren’s contracture of the palmar fascia, and trials of collagenase therapy have been undertaken as an alternative to surgery in this condition.1–4
Fournier’s gangrene is a potentially life-threatening, rapidly progressing, soft tissue infection within the spectrum of necrotizing fasciitis. Patients need urgent resuscitation, intravenous antibiotics, and early debridement in the OR, as in this case. Following initial debridement, the wounds should be temporized with simple dressings with or without topical antibiotics. Sometimes it is necessary to place the testes in temporary thigh pouches or suture them together to stop retraction. The wounds should then be revisited in the OR within 24 hours, or sooner if the patient remains unwell or has visible spread of continued infection/necrosis. There is no justification for attempting to close the wounds at this stage or apply a negative-pressure dressing. A negative-pressure dressing can, however, be very useful beyond the second assessment to manage wound exudate and reduce the defect size, providing that infection is controlled and a satisfactory seal can be achieved. Reconstruction should only be initiated once the infection has completely resolved. Skin grafts are usually preferred for the lower abdomen and groin rather than attempts at direct closure, with or without local tissue flaps or undermining.1–3