How accurate is the prenatal diagnosis of abnormal genitalia?

Purpose: The prenatal diagnosis of abnormal genitalia may have a major impa ct on prenatal counseling and postnatal outcome. We studied the accuracy an d clinical implications of the prenatal diagnosis of abnormal genitalia. Materials and Methods: Between 1991 and 1999 the prenatal and/or postnatal diagnosis of abnormal genitalia in 53 cases was made at our institution. Al l cases were prenatally assessed at our Obstetrics and Fetal Medicine Depar tment. Outcome was confirmed postnatally or by a fetopathologist in the cas e of pregnancy termination. Results: A genital anomaly was prenatally diagnosed in 43 cases and was acc urate in 34, while in 9 cases anomalies were absent at birth. In 10 eases a mbiguous genitalia were not detected prenatally. The primary anomalies susp ected were male pseudohermaphroditism in 19 cases and female pseudohermaphr oditism in 12, including 2 cases of congenital adrenal hyperplasia. Male ps eudohermaphroditism was detected prenatally in 17 cases and diagnosis was c onfirmed at birth. Female pseudohermaphroditism was detected prenatally in 12 cases and only 5 were confirmed and the anomaly was discovered at birth in 6. The prognosis was highly altered when many malformations or aneuploid y was associated with ambiguous genitalia. Of the 15 patients with many mal formations only 3 survived, and pregnancy was terminated in 3 of 4 cases of aneuploidy. Conclusions: When pseudohermaphroditism was detected in a male fetus by an experienced ultrasonographer at a tertiary center the prenatal diagnosis wa s accurate in 100% of cases. The prenatal diagnosis was less accurate (46% correct) in a female fetus.