Bifid scrotum and anocutaneous fistula associated with a perineal lipomatous tumor complicated by temporary bilateral cryptorchidism in utero mimicking ambiguous genitalia: 2-D/3-D fetal ultrasonography.

Ambiguous genitalia (AG) is a morphological diagnosis defined as genitalia not typical of a male or female. Findings mimicking AG, such as penoscrotal anomalies, anorectal malformations, and perineal lipomatous tumors, may prevent accurate identification of the fetal sex. We report a case of bifid scrotum and anocutaneous fistula associated with a perineal lipomatous tumor complicated by temporary bilateral cryptorchidism in utero, which were findings mimicking AG. Several perineal anomalies are associated developmental occurrences. In the present case, the combination of bifid scrotum and temporary bilateral cryptorchidism in the male fetus mimicked the combination of clitoromegaly and prominent labia, which are commonly observed in female fetuses. However, serial systemic assessments using prenatal 2-D/3-D ultrasonography and magnetic resonance imaging were unable to detect the anocutaneous fistula and differentiate the perineal lipomatous tumor. This case report suggests that the prenatal detection of perineal abnormalities may warn obstetricians of potentially undetected congenital perineal anomalies.