Genital Anomalies

Disorders of the external genitalia are especially troubling for parents because of the potential emotional significance of these reproductive structures and, probably, the possible impact of the anomalies on the child and on future generations.

The demonstration by researchers that castrated rabbit embryos of both sexes developed as females proved that testes are required for development of the male phenotype in mammals. ^[1]  Differentiation of the primitive gonad into testis is controlled by a multitude of genes, beginning with the sex-determining region on the Y chromosome (SRY), which is believed to represent the testis-determining factor. ^[2]

Until 8 weeks' gestation, the human fetus is undifferentiated sexually and contains both male (wolffian) and female (müllerian) genital structures. Wolffian ducts differentiate into the vas deferens, epididymis, and seminal vesicles. Müllerian ducts develop into the fallopian tubes, uterus, and upper one third of the vagina.

In the male fetus, the genital tubercle enlarges to form the penis; the genital folds become the shaft of the penis; and the labioscrotal folds fuse to form the scrotum. Differentiation occurs during weeks 12-16 of gestation and is the result of testicular hormones acting on the undifferentiated genitalia in the following ways:

• Testicular secretion of antimüllerian hormone (AMH), also known as müllerian inhibiting substance (MIS), leads to regression of the female müllerian structures
• Testosterone and its active metabolite, dihydrotestosterone, determine full differentiation and stabilization of internal and external genitalia ^[3]

In the female fetus, without the influence of AMH, the müllerian ducts complete their differentiation, whereas the wolffian structures involute. In the absence of testosterone and dihydrotestosterone, the genital tubercle develops into the clitoris, and the labioscrotal folds do not fuse, leaving labia minora and majora.

For patient education resources, see the following:

• Males - Men's Health Center, as well as  The Male Anatomy
• Females -  Women's Health Center

Penile agenesis

Congenital absence of the penis (aphallia), is an extremely rare anomaly caused by developmental failure of the genital tubercle. Its approximate incidence is 1 case per 30 million population. The phallus is completely absent, including the corpora cavernosa and corpus spongiosum; however, some children reportedly have small portions of corpora cavernosa. ^[4]  Usually, the scrotum is normal and the testes are maldescended. The urethra opens at any point of the perineal midline from over the pubis to, most frequently, the anus or the anterior wall of the rectum.

More than 50% of patients with penile agenesis have associated genitourinary anomalies, the most common of which is cryptorchidism; renal agenesis and dysplasia also occur. Gastrointestinal (GI) defects, such as caudal axis anomalies, have also been described. Reports indicate that aphallia may be associated with pregnancy complicated by poorly controlled maternal diabetes. ^[5]

Historically, these infants have undergone gender reassignment surgery, including bilateral orchiectomy with preservation of scrotal skin for later vaginal reconstruction, labial construction, and urethral transposition. However, questions remain regarding in-utero gender imprinting and long-term psychological effects of gender conversion; the timing, role, and necessity of gender reassignment are controversial. The long-accepted notion regarding the presence of a phallus or phenotypic phallic growth potential should not be the major criterion in recommending gender reassignment.

Because some studies have emphasized that most of these patients have a male sex identity despite reconstruction as female, male sex assignment has been recommended as a prudent decision. ^[6] Accordingly, patients with aphallia should be raised as male, though experience with phalloplasty in pediatric-age patients is limited.

The most commonly performed phalloplasty procedure in postpubertal patients is the microvascular transfer radial forearm flap. For congenital aphallia, a technique by De Castro has been described ^[7] that is based on a suprapubic skin flap as initially described by Bettocchi et al. ^[8] An alternative surgical technique, especially for the presence of midline suprapubic abdominal scars, is a vascularized groin flap fashioned as reported by Perovic. ^[9] A modified scrotal flap technique involving the addition of an acellular dermal matrix patch has been described as well. ^[10]

Penile duplication

Duplication of the penis (diphallia) is another extremely rare anomaly resulting from incomplete fusion of the genital tubercle. Two distinct forms of penile duplication are recognized, as follows:

• The most common form is associated with bladder-exstrophy complex; the patient exhibits a bifid penis, which consists of two separated corpora cavernosa that are associated with two independent hemiglands
• The second form (true diphallia ^[11] ) is an extremely rare congenital condition that presents in many ways, ranging from duplication of the glans alone to duplication of the entire lower genitourinary tract; the urethral opening can be in normal position or in a hypospadiac or epispadiac position

Associated anomalies of the GI, genitourinary, and musculoskeletal systems are expected. Because these anomalies are the principal causes of mortality, examining and treating patients for these conditions as soon as possible is important.

Microphallus

The term microphallus, or micropenis, is applicable only to a normally formed yet abnormally short penis. Specifically, the term applies to a penis with a stretched length that is more than 2.5 standard deviations (SD) below the mean for age. ^[12]

This condition may be considered a minor form of ambiguous genitalia with correlated medical and psychological problems similar to those of the major form seen in a difference (disorder) of sex development (DSD). The scrotum is usually normal, but testes may be small and undescended. In a few cases, the corpora cavernosa are severely hypoplastic. Measurement (ie, stretched penile length) is very important in differenting the various types of pseudomicropenis, particularly the buried penis in the obese infant and the penis concealed by an abnormal skin attachment.

Micropenis results from a multiplicity of endocrine and nonendocrine conditions. The most common etiologies are as follows:

• Hypogonadotropic hypogonadism - In this condition, secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus is impaired, which leads to decreased pituitary secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), depriving the testis of its stimulus to secrete testosterone; this pathogenesis is recognized in some hypothalamic dysfunctions, such as Kallmann syndrome or Prader-Willi syndrome
• Hypergonadotropic hypogonadism - Micropenis secondary to this condition is associated with conditions in which the testes are functionally impaired and unable to respond to hypothalamic-pituitary stimulation (eg, gonadal dysgenesis)
• Idiopathic micropenis - In this condition, endocrine analysis demonstrates a normal hypothalamic-pituitary-testicular axis

Because micropenis is the result of numerous pathologic conditions, assignment of sex of rearing has generally been deferred until a physician determines a potential cause and whether the penis can grow in response to testosterone administration. In individuals with microphallus who are insensitive to the androgen, castration and gender conversion might be an option. However, in most patients with micropenis, male gender assessment can be maintained with androgen stimulation.

Clinical management of micropenis has been contentious, with disagreement regarding the capacity of testosterone treatment to induce a functionally adequate adult penis; moreover, there is no general consensus regarding dosage, method of administration, timing, and duration of androgen treatment. The most common therapeutic regimen includes testosterone enanthate, 25-50 mg intramuscularly (IM) once a month for 3 months. Some physicians also use testosterone cream, but its absorption varies and is not easily controllable. ^[13]

Debate also surrounds the timing of androgen stimulation. Research indicates that testosterone therapy in infancy and childhood augments penile size into the normal range for age in boys with micropenis secondary to fetal testosterone deficiency. ^[13] Replacement therapy at the age of puberty is indicated for gonadal deficiency. Final adult penis size is usually below the mean but within 2.5 SD. ^[14]

In a small (N = 6) single-center study aimed at assessing the effects of continuous subcutaneous infusion of recombinant human gonadotropins on stretched penile length and hormone levels in infants with congenital micropenis, Stoupa et al found that this approach safely corrected micropenis in five of the six patients, including the one infant with partial androgen insensitivity syndrome. ^[15] Long-term follow-up data will be necessary to determine whether this treatment has any impact on future fertility and reproduction.

Penile torsion

Verneuil first described penile torsion in 1857. In the past, physicians did not recommend operative correction, because they believed that attempts to move the skin would not correct spiral alignment of the corpora cavernosa.

The embryologic abnormality is often an isolated skin and dartos defect that can be remedied simply by freeing the penile shaft of its investing tissue. The rotation is usually to the left in a counterclockwise fashion. The urethral meatus is placed in an oblique position, and the median raphe makes a spiral curve from the base of the penis to the meatus. However, in some cases, penile torsion is associated with mild forms of hypospadias or hooded prepuce.

Frequently, torsion is corrected by reflection of the skin and dartos tunic only. In some cases, resection of the Buck fascia provides correction. Careful alignment of the skin during closure gives an excellent cosmetic result, even when the torsion is not corrected by reflection of the penile investments. A newer technique has been described that is based on a dorsal dartos flap rotated around the right side of the penile shaft and attached to the ventral aspect. ^[16]  The relative ease of achieving a normal appearance seems to justify surgical correction.

Lateral penile curvature

Congenital penile curvature secondary to asymmetry of corpora cavernosa length is an uncommon penile deformity. Hemihypertrophy of a corpus cavernosum and thickening of its accompanying tunica albuginea, with or without contralateral concomitant hypoplasia (rudimentary corpus), are responsible for the lateral deviation in congenital curvature of the penis. Rarely, penile deviation is accompanied by penile torsion. The anomaly can be associated with trauma, but often the patient does not have a history of corporal injury.

Although the deformity generally is not severe enough to preclude sexual intercourse, it can be a source of great concern to the patient and may cause him to avoid sexual contact. The Nesbit procedure is a simple effective surgical technique to correct lateral or ventral curvature. Good results have been reported for both the modified Nesbit corporoplasty and the Lue 16-dot plication technique ^[17] ; the reported success rates of corporal plication were similar in prepubertal and postpubertal boys. ^[18]

Penoscrotal transposition

Complete penoscrotal transposition is an uncommon condition in which the scrotum is located in a cephalad position with respect to the penis. A less severe form is a bifid scrotum, in which the two halves of the scrotum meet above the penis. It is a heterogeneous anomaly, and detection warrants careful clinical evaluation to rule out other major and life-threatening anomalies, especially of the urinary system, GI tract, upper limbs, craniofacial region, and central nervous system (CNS).

Major renal anomalies include complete agenesis of the urinary system, unilateral or bilateral renal agenesis, polycystic or dysplastic kidneys, horseshoe kidney, ectopic pelvic kidney, and obstructive uropathy. Genital abnormalities include a disproportionately long flaccid penis, complete urethral atresia, and hypospadias.

Although most reported cases are sporadic, some suggest a genetic basis for a normal penoscrotal relation. The embryologic sequence responsible for this defect remains unclear. Abnormal positioning of the genital tubercle in relation to the scrotal swellings during the critical period at 4-5 weeks' gestation may affect the inferomedial migration and fusion of the scrotal swellings.

If the phallic tubercle is also intrinsically abnormal, development of the corporal bodies and the urethral groove and folds may be affected; this explains the frequent occurrence of the other genital abnormalities. Accurate antenatal diagnosis of this malformation by means of ultrasonography (US) has been demonstrated. ^[19]

Surgical correction is recommended for physiologic and psychological reasons. When associated with severe hypospadias, penoscrotal transposition may involve a staged surgical repair. Scrotoplasty is completed with an inverted omega skin incision that is made around the scrotal skin and the base of the penis, bringing the scrotal flaps beneath the penis.

Webbed and buried penis

Webbed penis (see the image below) is a common congenital abnormality in which a web or fold of scrotal skin obscures the penoscrotal angle. If the physician performing circumcision does not recognize the condition, the penis may become buried in a tentlike fold of skin. Recircumcision to remove the excess skin makes the situation worse by drawing hair-bearing scrotal skin onto the penis.

In hidden penis, the penile shaft is buried below the surface of the prepubic skin. This happens in children with obesity because the prepubic fat is very abundant and hides the penis. The condition may also derive from poor anchorage of penile skin to deep fascia or may be acquired when the shaft of the penis is entrapped in scarred prepubic skin after an extreme circumcision or other trauma. Pensabene et al suggested that a primary buried penis should be viewed as an incomplete manifestation of a micropenis rather than as a simple defect of the penile ligaments and surrounding tissues. ^[20]

The literature describes numerous techniques for correction. ^[21] Usually, treatment is based on resection of adherent bands and deep anchorage of the shaft at the basis of the penis. Some also advocate excision of redundant skin, multiple Z-plasties, liposuction, or preputial island pedicle flap. Others advocate watchful waiting, with emphasis on weight loss and yearly follow-up. Ruling out micropenis in this situation is essential.

Megaprepuce

Congenital megaprepuce is a rare malformation of unknown etiology that is characterized by extensive redundancy of the inner preputial skin, which causes the penis to be buried within the prepuce. This condition may be associated with an abnormal distal preputial opening that prevents normal flow of urine from under the foreskin. ^{[22, 23, 24]} An enormous preputial cavity surrounds the entire shaft before micturition. In one of the first reported patients affected by congenital megaprepuce, micturating cystography was performed; the preputial volume was so huge that it was defined as a “preputial bladder.” ^[22]

The aspect of congenital megaprepuce is typical. The penis is totally buried, and before micturition there is an enormous preputial cavity surrounding the entire shaft; after urination, dribbling may be noted. Numerous surgical techniques have been described to correct this anomaly. The cosmetic arrangement of the shaft skin with excision of the redundant inner preputial skin, especially in the ventral part, is the more difficult step of reconstructive surgery.

Unfortunately, congenital megaprepuce is one such congenital deformity that at birth often goes unrecognized. Circumcision with congenital megaprepuce may yield catastrophic complications, such as scarred buried penis with possible flow obstruction.

Scrotal agenesis

Aside from penoscrotal transposition, the scrotum is generally resistant to embryologic abnormalities; therefore, congenital malformations are unusual. Congenital absence of the scrotum is an extremely rare anomaly ^[25] ; according to a report by Corona-Rivera et al, only nine cases (seven bilateral and two unilateral) had been described in the literature as of January 2014. ^[26]

Reports indicated that upon examination, the scrotum was not present, the skin between the base of penis and the anus was completely flat without rugosa, and both testes were retained in the tubercle area lateral to the base of the penis. Only minor associated abnormalities, including slight bilateral clinodactyly in both fourth toes and bilateral nystagmus, were noted. Chromosomal and hormonal anomalies were not reported.

The idea of constructing the scrotum with a pedicle flap from the perineal skin was discarded. In view of the subsequent development of the neoscrotum, the preputial skin was used because it is richer than other tissues in androgen receptors. The procedures were uneventful, and the results were functionally and cosmetically satisfactory. (See the images below.)

Ectopic and accessory scrotum

Ectopic scrotum is a rare anomaly that includes an anomalously positioned hemiscrotum. Usually, the ectopic scrotum is found near the external inguinal ring, but it may assume several forms. Accessory scrotum is a small empty pouch of scrotal tissue attached to the scrotum or the perineum. One review identified 16 reported cases of a suprainguinal ectopic scrotum, four cases of a femoral ectopic scrotum, and 19 cases of accessory perineal scrotum. ^[27]

The testis generally accompanies the hemiscrotum to its abnormal position and may be normal or dysplastic. These congenital lesions of the scrotum can occur as an isolated anomaly but are often accompanied by abnormalities of the upper urinary tract.

Accessory perineal scrotum has also been observed in association with anorectal malformation. ^[28]  The gubernaculum is a prerequisite for the ultimate location of both the testis and scrotum, and its role is complicated by subsequent differential growth of the labioscrotal folds in which the gubernaculum is stabilized. If this interaction is disturbed, the result may be suprainguinal ectopia, penoscrotal transposition, or perineal scrotum.

Although the etiology of these malformations is probably multifactorial, the existence of an inbred strain of rats that are characterized by a high incidence of ectopic scrotum suggests a genetic component to this anomaly.

Treatment should attempt to bring down the scrotum and the testis. If the gonad is dysplastic and the ectopic scrotum is rudimentary, removal of one or both structures should be considered.

Splenogonadal fusion

Splenogonadal fusion is a congenital anomaly that affects both sexes, with a male-to-female ratio of 16:1. ^[29] In males, the left testicle or other derivatives of the mesonephros connect to splenic tissue, usually an accessory spleen. In the female, a similar fusion occurs between the left ovary and splenic tissue. The connection may be either continuous (56%) or discontinuous (44%). In the continuous type, the spleen is connected to the gonad by a strand of tissue.

Patients often exhibit limb defects, micrognathia, or other congenital malformations, such as anal atresia, microgastria, spina bifida, craniosynostosis, thoracopagus, diaphragmatic hernia, hypoplastic lung, and abnormal lung fissures. The discontinuous type is not usually associated with congenital defects, and the fused gonad has no connection with the native spleen ^[30] .

As of 2023, only about 200 cases had been reported, mostly in the urology and pathology literature. ^{[29, 31, 32, 33, 34]} This is because diagnosis typically occurs during orchiopexy or herniorrhaphy, or on autopsy.

In many cases, the accessory spleen that is attached to the testicle may be misinterpreted as a primary malignant testicular tumor or an adenomatoid tumor. Knowledge of this distinction is important if the testis is to be preserved at surgery, though a rare case of simultaneous splenogonadal fusion and mixed malignant tumor of the testis has been reported. ^[35]

If splenogonadal fusion is suspected preoperatively, technetium-99m radiocolloid spleen scintigraphy can establish the correct diagnosis and permit testicular salvage. Simple excision of the splenic nodule is sufficient in all cases of discontinuous fusion. In continuous splenogonadal fusion, exploratory laparotomy is usually required to clarify the anatomy.

Labial adhesion

Labial adhesion (see the image below) is an acquired anomaly frequently encountered in prepubertal girls; its etiology is unclear, but it is generally presumed to result from reepithelization of microtraumatized hypoestrogenized labial skin in combination with chronic inflammation of the vulva. ^{[36, 37]} This condition must be distinguished from labial fusion, a different rare lesion attributed to in-utero virilization of the female external genitalia.

Labial adhesion usually is asymptomatic, but when the introitus is completely sealed, vaginal micturition with consequent dribbling can occur; moreover, urinary stasis can predispose the child to UTI. A single case of hydroureteronephrosis has been reported as an extreme and unusual complication that resolved after incision of the adherent labia. ^[38]

Treatment consists of topical application of 1% estrogen cream three times daily for 2 weeks; this is usually ineffective but does facilitate subsequent manual lysis. The procedure may be performed in an office setting with a cotton-tipped swab or a probe. When the lesions are dense, the patient may require sedation. Topical application of estrogen or antibiotic cream after the procedure is important to avoid recurrence of the adhesion. In the event of persistent symptomatic readhesion, suturing of the labia majora with an absorbable stitch is an effective long-term treatment.

Ectopic labium majus and clitoral duplication

Ectopic labium majus is a rare anomaly and is homologous with ectopic scrotum in the male. It has been reported with renal agenesis or dysplasia and the VATER (vertebral defects, anal atresia, tracheoesophageal fistula, esophageal atresia, renal anomalies) association. Clitoral duplication is also a very rare anomaly, usually seen in the bladder exstrophy-epispadias complex in girls.

Clitoral hypertrophy

Hypertrophy of the clitoris (see the image below) is observed in cases of fetal exposure to androgens. The disorder is usually the result of congenital abnormalities of the adrenal enzymes responsable for cortisol synthesis, as is seen in certain female forms of DSD; more rarely, it is caused by idiopathic virilization or exposure to progestational agents in utero. ^[39] Clitoral hypertrophy caused by neurofibromas of the clitoral corpora, though rare, has been described, including a case of localized neurofibromatous infiltration of the prepuce only. Transient clitoral preputial edema can be misinterpreted as clitoromegaly. ^[40]

Treatment is dictated specifically by the degree of clitoral hypertrophy and the need for vaginal reconstruction. The various surgical techniques employed for management of clitoromegaly can broadly be divided into three categories as follows ^[41] :

• Clitorectomy
• Reduction clitoroplasty
• Corpora-sparing techniques

Reduction clitoroplasty with resection of the corpora according to the Spence-Allen technique has given better results than the plication technique described by Pelleren; furthermore, the latter technique often is complicated by painful engorgement of the recessed corpora at puberty. ^[42] A newer surgical technique for clitoroplasty has been reported that completely preserves corporeal bodies and neurovascular bundles without dismembering the clitoris. ^[43]

Interlabial masses

Identification of an interlabial mass in a young girl may cause much concern in parents and physicians because of confusion about diagnosis, etiology, implications, and treatment. However, knowledge of the most frequent anomalies responsible for interlabial masses may allow a prompt and correct assessment.

Urethral prolapse

Urethral prolapse, an uncommon entity that primarily occurs in prepubertal Black girls, involves circumferential eversion of the distal urethral mucosa at the level of the external meatus. Patients present with perineal bleeding and are diagnosed upon physical examination that reveals a purplish dark lesion of variable size located right above the vaginal hymen. Anatomic defects include marked eversion of the urethral mucosa, vascular congestion of the corpus spongiosum urethrae muliebris, and a cleavage plane between the inner longitudinal and outer circular-oblique smooth-muscle layers of the urethra.

Some have suggested that urethral prolapse results from poor attachments between the smooth-muscle layers of the urethra that are aggravated by episodic increases in intra-abdominal pressure. Treatment consists of excising the prolapsed urethral mucosa and suturing the remaining mucosa to the mucosa of the vestibule.

Prolapsed ectopic ureterocele

Another cause of interlabial mass, prolapsed ectopic ureterocele, appears as a smooth cystic mass that protrudes from the urethral mucosa and obscures it. Ectopic ureteroceles are associated with an upper moiety of a duplex renal collecting system. Any combination of vesicoureteral reflux (VUR) or obstruction in any of the associated renal units may result, but upper-pole obstruction and lower-pole reflux are most common. The child may present with urinary symptoms such as straining to void; this is felt to be due to the ureterocele ball-valving at the level of the bladder neck.

Management of this condition should be based on a careful urologic evaluation and tailored to the findings, with the presence of VUR and upper-pole renal moiety function being important factors in the decision-making process.

Hydrocolpos or hydrometrocolpos

Accumulation of fluid due to congenital vaginal obstruction is the cause of hydrocolpos (ie, vaginal distention due to fluid) and hydrometrocolpos (ie, distention of the vagina and uterus). The obstruction process is frequently caused by imperforate hymen or, less commonly, transverse vaginal septum. Obstructing genital anomalies may present at birth with mucocolpos (mucus being the accumulated fluid), but the obstructive anomaly is often asymptomatic and escapes detection.

An imperforate hymen is often difficult to diagnose perinatally because of the small size of the genitalia and the influence of maternal estrogens, which cause thickening and enlargement of the labia minora. The neonate with hydrocolpos related to congenital vaginal obstruction can present with a bulging interlabial cyst (see the image below), associated with a mass in the lower abdominal quadrants, often inducing urinary tract obstruction.

Achieving a correct diagnosis is the most difficult aspect of management. In the past, the abdominal swelling was sometimes mistaken for an ovarian cyst, and the patient was subjected to laparotomy. Today, abdominal US helps to determine the anatomy, revealing a large midline translucent mass displacing the bladder forward. If the imperforate hymen is not associated with a palpable mass on rectal examination, surgical correction can be delayed until tissues are estrogenized; however, it should be performed before the occurrence of hematocolpos. ^[44]

If no abdominal mass is present at birth, congenital vaginal obstruction may only become evident at menarche, when the child presents with primary amenorrhea, and intermittent or chronic lower abdominal pain, which is usually caused by accumulation of menstrual blood (ie, hematocolpos)  within the blind ending of the vaginal lumen.

The vagina can accommodate a considerable volume of blood, but a small amount may collect in the uterus (ie, hematometra). Physical signs are similar to those of hydrocolpos and include lower abdominal mass and a bulging membrane at introitus (bluish in this case; see the image below). Treatment consists of a cruciate incision in the membrane with excision of the excess mucosal tags; in most instances, the procedure is curative, and no further procedure is necessary.

Sarcoma botryoides or rhabdomyosarcoma

Sarcoma botryoides or rhabdomyosarcoma is another cause of interlabial mass and is considered the most common malignant tumor of the lower genitourinary tract in infant girls. The presenting symptoms may be vaginal bleeding or a firm grapelike vaginal mass protruding through the introitus. Patients presenting with these findings on physical examination should be evaluated with US and computed tomography (CT).

Other masses of the introitus include polyps of the urethra, ^[45] hymen (see the first image below), and vagina (see the second image below). In these cases, surgical resection is mandatory to assess the histology and to exclude neoplastic lesions (especially rhabdomyosarcoma).

Vaginal skin tags

Hymenal tags, also known as hymenal polyps, are not uncommon findings in infant girls. Clinically, a hymenal tag presents as an elongated projection of hymenal tissue extending from the hymenal rim. The majority of these lesions are small and do not need treatment; spontaneous resolution has been observed before the age of 3 years. ^[46]

Periurethral cyst

Periurethral cyst is a rare lesion that probably arises from embryonic remnants of the urogenital ducts, müllerian structures, or mesonephric (Gartner) duct. Diagnosis is based on identification of the cyst on the urethral meatus and direct needle aspiration of a small quantity of its milky fluid. Spontaneous rupture or regression has been observed, but incision and drainage are indicated for persistent lesions.

Similar cystic lesions have been described in males. Since the first report in 1956 by Thomson and Latin, fewer than 50 additional cases have been reported. The origin of these cysts is unknown, but they may result from a parameatal glans obstruction. Treatment consists of simple unroofing or total excision of the lining to avoid recurrence. ^[47]

Persistent urogenital sinus and cloaca

Congenital malformation involving the urogenital sinus and cloaca remains one of the most severe birth defects compatible with life. Moreover, management of this malformation is one of the greatest challenges of pediatric surgery and urology. Development of the lower urinary tract and genital and anorectal systems is correlated closely in females. Consequently, abnormal embryologic development can involve all three systems.

Despite the long tradition of embryologic studies, the mechanisms of development of many congenital malformations are still debated. In very young embryos, the hindgut is a simple structure that is in continuity with the midgut cranially and with the ectoderm caudally, thus forming the cloacal membrane.

As development progresses, the caudal part of the hindgut or cloaca separates into two distinct organ systems, the urogenital tract and the anorectal tract. This separation may be the result of a subdivision of the cloaca by a septum, the so-called urorectal septum. However, the nature of this septum and its mechanism of development are controversial.

Kluth and Lambrecht demonstrated that the hindgut enters the cloaca from the dorsocranial direction, whereas the allantois (ie, the forerunner of the bladder) can be individuated as a cranioventral diverticulum. ^[48] The urorectal folds can be observed between this diverticulum and the hindgut, marking the cranial border of the undifferentiated hindgut or cloaca.

The importance of the septation process has likely been overestimated, and normal development of the hindgut probably depends primarily on normal formation of the cloacal membrane. After the cloacal septum separates the hindgut from the urogenital sinus, the fused caudal ends of the müllerian ducts form the müllerian tubercle as they come in contact with the posterior aspect of the sinus.

Persistence of the urogenital sinus can be associated with anorectal anomalies. Two different situations can arise. In the first, agenesis of Rathke plicae and failure of the müllerian ducts to migrate to the vestibule result in a persistent cloaca with a possibly septated vagina; in the second, defective caudal migration of the müllerian ducts or failure of the distal sinus to evert gives rise to persistence of the urogenital sinus after urorectal septation has occurred.

Clinically, persistent urogenital sinus in females is classified into the following three categories:

• Simple urogenital sinus in patients with normal anus and rectum and without DSDs
• Urogenital sinus in patients with DSDs
• Urogenital sinus associated with anorectal malformation (ie, persistent cloaca)

Simple urogenital sinus is defined as a common channel into which genital and urinary tracts both open. Depending on the timing of the arrest of vaginal differentiation, various degrees of anomaly can be identified, as follows:

• An early-stage defect is characterized by a long urogenital sinus with a short vagina and a high urethral opening
• Later-stage anomalies are characterized by a short urogenital sinus with an almost normal vagina and low urethral orifice
• The most severe degree of urogenital sinus persistence often is associated with anterior displacement of the anus, suggesting that a urorectal septum anomaly also is involved

The most important points in patient evaluation are definition of the exact anatomic picture, ^[49] investigation of other anomalies (especially of the genital and urinary tracts), and identification of the mechanism of incontinence, if present.

Genitography, with retrograde injection of contrast material, is useful for delineating the anatomic aspects of the sinus and for clarifying the relation between the vagina and the urethra. Voiding cystourethrography (VCUG), urodynamic studies, and endoscopy are essential. US of the upper urinary system and pelvis can help screen for associated anomalies and define internal genital anatomy.

Anatomy dictates treatment. If the urogenital sinus is low, simple U-flap vaginoplasty is effective in correcting the anomaly. If the vaginal entry into the urogenital sinus is high, a more challenging surgical approach is required. In fact, a division of the vaginal moiety with an associated pull-through vaginoplasty is needed. Moreover, relocation of the anus, if displaced anteriorly, may be necessary.

Persistent urogenital sinus may be associated with an anorectal anomaly called persistent cloaca. Girls with persistent cloaca have the typical appearance of a closed perineum with a single orifice located behind the clitoris and no anus or vagina. If the convergence of bladder, vagina, and colon is low, the appearance may be of a relatively normal female perineum with imperforate anus. In such patients, obstruction of the urinary system is uncommon, because it opens, like the vagina and rectum, into a wide funnel-shaped urogenital sinus that drains freely.

However, when the three organ systems converge at a higher level, the urogenital sinus is long. Frequently, the skin folds around the clitoris are so prominent that the structure has the appearance of a penis, thus inducing an erroneous gender assignment. In these cases, obstruction of the urinary tract is common.

Treatment of the various forms of persistent cloaca is one of the most challenging problems of reconstructive surgery in pediatrics. Once the anatomy has been clearly defined, ^[50] surgery may be performed. Most surgeons perform a colostomy to relieve colon obstruction. Distention of the bladder and vagina, which often obstructs both ureters, may be relieved by intermittent catheterization, thus avoiding the necessity of vesicostomy or vaginostomy. Complete definitive reconstruction for cloacal persistence should be deferred until the child is older than 1 year.

When the sinus is shorter than 3 cm, the rectum is mobilized and detached from the vagina. The sinus should not be opened but should be mobilized and brought down intact. The common channel is divided, and the separated openings of the urethra and vagina are placed in their normal positions. When the common channel of the cloaca is longer than 3 cm, the posterior approach to correction is preferred. Hendren emphasized the necessity of correcting both urinary and rectal defects simultaneously. ^{[51, 52]}

Minimally invasive approaches to surgical treatment of cloaca have been described. ^{[53, 54]}