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Abnormalities of the External Genitalia

HYPOSPADIAS

Hypospadias is one of the most common genital anomalies that pediatric urologists treat. This defect is easily recognized in most cases, so it is no wonder that hypospadias has been referred to throughout recorded history. The term hypospadias is derived from the Greek word hypo, meaning "under," and spadon, meaning "rent" or "fissure." Hypospadias is a congenital abnormality of the penis that is caused by incomplete development of the anterior urethra. The meatal location can be located anywhere on the ventral surface of the penis, from just below the tip of the glans to the perineum in the most severe cases. Chordee, ventral curvature of the penis, is frequently seen with hypospadias but sometimes is not recognized until an erection test is performed at the time of surgery. Penile torsion or rotation of the penis to the left or right can also be found with hypospadias.

Embyrogenesis

Until the eighth week of embryonic development, fetuses do not differentiate into male or female. Differentiation of the primitive gonad into the testis depends on the presence of genetic material found on the Y chromosome.

Classification

Hypospadias can be classified in several ways. A popular but older classification system was based on Smith's work, wherein hypospadias was classified as first, second, or third degree based on the meatal location.

Incidence

Hypospadias is found commonly in newborn boys and it is seen in approximately 8.2 per 1000 live births. Hypospadias may be inherited, although it is mostly an isolated finding.

Etiology

According to the findings in a report that reviewed cases over a 30-year period, neither maternal age, number of previous pregnancies, deliveries, stillbirths, abortions, preeclampsia history, twinning, number of cesarean sections.

Associated Anomalies

Undescended testes and inguinal hernias are the most common anomalies associated with hypospadias.

Treatment

Timing of Surgery

Before 1980 hypospadias repair usually was performed after age 3 years because of technical considerations. It has been shown that genital surgery at this age could prove psychologically traumatic. Aberrant behavior, feelings of guilt, and gender identity confusion were noted commonly. Manley and Epstein demonstrated disturbing behavioral changes in boys who had surgery between ages 2 and 6 years and subsequently began performing hypospadias.

EXSTROPHY AND EPISPADIAS

Bladder exstrophy is a rare and calamitous congenital anomaly. This condition represents a wide spectrum of anomalies secondary to abnormal development of the cloacal membrane. Classic bladder exstrophy is found in approximately 1 in 30,000 births and accounts for 60% of the various anomalies seen.

Embryologic and Anatomic Considerations

The most commonly espoused theory for exstrophy development comes from the work of Marshall and Muecke, who postulated that early in gestation the cloacal membrane develops abnormally. The typical migration of mesenchyme from the lateral margins of the cloacal membrane medially is inhibited.

Cloacal exstrophy presents with an impressive anatomic array of associated external defects , including the exstrophic cecum and terminal ileal segment separating the bladder into two exstrophic halves. An omphalocele may be present that may include a large portion of the bowel and other organs, including the liver and spleen. In large omphaloceles, abdominal wall closure is exceedingly difficult and may require staged surgery. The phallus in boys is completely and widely separated in half and is small. These findings make penile reconstruction very difficult, if not impossible. Therefore, female gender assignment is the recommendation in most boys born with cloacal exstrophy. Girls also can present with a separated clitoris, a bifid uterus, a duplicate vagina, or an exstrophic vagina.

Management

Upon recognizing a patient with exstrophy, either antenatally or immediately upon birth, referral to surgical specialists at tertiary centers who are experienced should be made without delay.

AMBIGUOUS GENITALIA

Ambiguous genitalia newborn infants can be challenging and confusing for practitioners. To provide an appropriate plan of treatment, it is essential to have a general understanding of the different abnormalities.

FEMALE PSEUDOHERMAPHRODITISM

Typically, these patients have normal ovaries, internal female ductal systems, 46,XX karyotype, and virilization of the external genitalia. The external genitalia are masculinized to a variable degree ranging from mild clitoral enlargement to normal male phenotype with an empty scrotum.

MALE PSEUDOHERMAPHRODITISM

These genotypic males (46,XY) have two testes but an altered phenotype caused by abnormal cellular response to testosterone in 80% of cases and deficient testosterone production in the rest. In the more common cases of androgen insensitivity, the defective androgen receptors may result in external female genitalia with a blind-ending vagina and no mullerian or wolffian duct structures (complete testicular feminization).

MIXED GONADAL DYSGENESIS

Mixed gonadal dysgenesis is caused by chromosomal mosaicism (45,XO, 46,XY) and is one of the more common forms of ambiguous genitalia. Many of these patients seem to have the appearance of patients with classic Turner's syndrome. The internal findings including a streak gonad associated with an ipsilateral fallopian tube and uterus with a contralateral, dysgenetic testis. The streak and testis are both at risk for the malignant transformation. Often, treatment includes gonadectomy with female assignment. Patients who are reconstructed as boys with the testis left in place must be monitored carefully.

PURE GONADAL DYSGENESIS

In patients with pure gonadal dysgenesis, phenotypic girls may have a variable karyotype (46,XO, 46,XX, 46,XY), normal external female genitalia, and bilateral streak gonads. They often present at puberty with amenorrhea.

TRUE HERMAPHRODITISM

True hermaphroditism is an extremely rare form of intersex, accounting for fewer than 10% of all intersex disorders. Most of these patients are genotypic girls (46,XX) who have some Y-chromatin material. Ten percent are male

Evaluation and Management

Evaluation of infants with ambiguous genitalia requires a high index of suspicion that begins in the delivery room. It is imperative that members of the health-care team (i.e., obstetrics, pediatrics, nursing, and specialists including endocrinologists.

VAGINAL ANOMALIES

Embryology

After the seventh week of gestation, the female reproductive tract arises from the paired mullerian ducts.

ABSENT VAGINA

Congenital vaginal agenesis, also known as the Mayer-Rokitansky syndrome, develops when the vaginal plate fails to canalize. These patients are normal genetic female patients (46,XX) and present at puberty with primary amenorrhea and normal external female genitalia. Many of these patients have renal anomalies also, including renal agenesis; renal ectopia; or fusion.

VAGINAL OBSTRUCTION

Obstruction of the vagina most likely results from an incomplete formation of the vaginal canal during gestation. Hydrocolpos is defined as vaginal obstruction only, whereas hydrometrocolpos refers to blockage and distension of the vagina and uterus. Imperforate hymen, vaginal septum, or vaginal atresia.

VAGINAL OR UTERINE DUPLICATION

Disruption of the fusion process of the mullerian structures can result in a variety of duplication anomalies. A result of partial fusion can lead to a bicornuate uterus with a single vagina or complete duplication with uterus didelphys.

Evaluation and Management

Detection of vaginal anomalies depends on the time of presentation, varying from an abdominal mass to bulging introitus in newborn infants to cyclical abdominal pain and amenorrhea at puberty. Obvious findings of an absent or blind-ending vagina lead to the diagnosis of vaginal agenesis. Rectal examination with bimanual palpation in older patients may help to detect masses.