Masculinized external genitalia can be classified into five “Prader” stages. Excessive androgen exposure results in virilization to varying degrees, including clitoral enlargement, labial fold fusion, and rostral migration of the urethral/vaginal perineal orifice. Prader stage V defines virilization resulting in complete labioscrotal fusion, a penile phallus with the urethra opening on the glans. Clitoroplasty is required at an early stage after it is established that a Prader stage V “male” has CAH and needs to be reassigned to the female sex (104).
Teratogens It is important to recognize that ambiguous genitalia can result from the maternal ingestion of various teratogens, most of which are synthetic steroids (Table 29.3). Exposure to the teratogen must occur early in pregnancy, during genital organogenesis. Not all exposed fetuses manifest the same anomalies or even the presence of any anomalies. In principle, most synthetic steroids with androgenic properties, including weakly androgenic progestins, can affect female genital differentiation. The doses required to produce genital ambiguity are generally so great that the concern is only theoretical. The one agent that can lead to genital ambiguity when ingested in
Table 29.3 Androgens and Progestogens Potentially Capable of Producing Genital Ambiguitya aThose agents proved to cause genital ambiguity do so only when administered in relatively high doses. Insufficient data exist regarding effects of dimethisterone and norgestrel. In low doses (e.g., as in oral contraceptives), progestins, even including norethindrone, seem unlikely to virilize a female fetus.
clinically used quantities is danazol. There is no evidence that inadvertent ingestion of oral contraceptives, which contain relatively low doses of either mestranol or ethinyl estradiol and a 19-nor-steroid, results in virilization (105,106).
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