The diagnosis of immature teratoma by maternal serum alpha-fetoprotein screening.

We report a case in which maternal serum alpha-fetoprotein (MSAFP) screening of a low-risk patient led to the antepartum detection of an asymptomatic and previously undetected stage Ia immature teratoma of the ovary. It is widely accepted that MSAFP screening is valuable in the antepartum diagnosis of neural tube defects, ventral wall defects, and aneuploid fetuses. Similarly, such screening may lead to the diagnosis of AFP-producing neoplasms not appreciated on physical or ultrasonic examinations. This benefit, though extremely rare, is significant when a potentially aggressive malignancy is detected in the earliest stages, prior to extraovarian spread.