Hypospadias

Hypospadias is a birth defect of the urethra in the male that involves an abnormally placed urethral meatus (opening). Instead of opening at the tip of the glans of the penis, a hypospadic urethra opens anywhere along a line running from the tip along the ventral (bottom) shaft to the junction of the penis and perineum.

Hypospadias are among the most common birth defects of the male genitalia (second to cryptorchidism) and occur in about 1 in 150 boys. The urethral meatus opens on the glans in about 75%; these are categorized as first degree. Second degree (when the urethra opens on the shaft), and third degree (when the urethra opens on the perineum, as in females) occur less often, but are more likely to be associated with chordee in which the phallus is incompletely separated from the perineum or is still tethered downwards by connective tissue.

The causes of most hypospadias are unknown. Most are sporadic, without inheritance or family recurrence. In animals, several teratogenic drugs or chemicals can cause hypospadias by interfering with androgen action in the embryo. Although a slight worldwide increase in hypospadias was reported in the 1980s, continued increases have not been documented and some registries have reported decreases. Speculation that environmental agents might be interfering with human hormone systems has not been proven. The agents that have caused hypospadias in a small number of boys have been maternal use of synthetic progestins and finisteride in the first two trimesters of pregnancy.

A minority of hypospadias arise from deficiencies of, or reduced sensitivities to, androgens (testosterone and dihydrotestosterone) during the third and fourth months of gestation. These are often associated with a chordee, and in severe cases a residual perineal urogenital opening and small phallus. This combination of birth defects is referred to as pseudovaginal perineoscrotal hypospadias and is part of the spectrum of ambiguous genitalia. Treatment with testosterone postnatally does not close the urethra.

First degree hypospadias are primarily a cosmetic defect and have little effect on function except for direction of the urinary stream. If uncorrected, a second or third degree hypospadias can make male urination messy, necessitate that it be performed sitting, reduce fertility, or interfere with erections. Most hypospadias are surgically repaired in infancy. Surgical repair of first and second degree hypospadias is nearly always sucessful in one procedure.

When the hypospadias is third degree, or there are associated birth defects such as a chordee, the best management can be a more complicated decision. Surgical repair may require multiple procedures and in a minority of patients produces unsatisfactory results, such as fistula formation or scarring. A fistula is an unwanted opening through the skin along the course of the urethra, and can result in urinary leakage or an abnormal stream. Because of the difficulties and lower success rate of surgical repair of the most severe degrees of undervirilization, some of these genetically male infants have been assigned and raised as girls, with feminizing surgical reconstruction. Opinion has shifted against this approach in the last decade because adult sexual function as a female has often been poor, as well as increased concern about development of a male gender identity despite female sex assignment and rearing, as has occurred in some children after reassignment for cloacal exstrophy.

A much rarer and unrelated type of urethral malformation is an epispadias. This is not a problem of the urethral groove or meatus, but a failure of midline penile fusion much earlier in embryogenesis. An isolated opening of the dorsal ("top") side of the penis is rare, and most of these children have much more severe defects, involving a small and bifid phallus with bladder exstrophy or more severely, cloacal exstrophy involving the entire perineum. The cause of this defect of early embryogenesis is unknown but does not involve androgens.

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