General Medical Information

Workup of Prepubertal Children With Ambiguous Genitalia

Claude J. Migeon and Gary D. Berkovitz

The workup of ambiguous external genitalia described in the previous section was devised for newborn infants. It is extremely important to establish early in life the etiology of the ambiguous genitalia and the preferred sex of rearing. Experience has shown that it is hazardous to make a change in sex after 1 or 2 years of age. The optimal time is in the first month of life.

On occasion, one is obliged to deal with a prepubertal child. Although the workup of the prepubertal child with abnormal external genitalia is directed to ask the same questions as those raised in infancy, the gonadal physiology has changed in certain aspects. In particular, Leydig cell function that was quite active during the first 3 months of life remains quiescent throughout childhood until puberty. To determine the potential of the gonads for androgen secretion, it is necessary to stimulate the Leydig cells by intramuscular administration of gonadotropins, usually hCG. The daily dose of hCG is adjusted for body size (3,000 IU per M2 of body surface area). One injection is given every day for 5 consecutive days. A blood sample is obtained before the injections and on the morning of the sixth day.

Interpretation of the values of the various androgens is similar whether after hCG stimulation in childhood or without exogenous stimulation in infancy. An hCG stimulation test also can be helpful in the rare infants with ambiguous genitalia and suspected hypopituitarism.

In some children, the adequacy of penile response to androgen stimulation may be questioned. On such occasions, the hCG stimulation is prolonged to 6 weeks, giving two or three injections weekly. This sustained stimulation results normally in increased penile size. This diagnostic test also is used for therapeutic purposes in male children with small phallus.