Markedly elevated maternal serum alpha-fetoprotein associated with a normal fetus and choriocarcinoma of the placenta.

Determination of maternal serum alpha-fetoprotein (MSAFP) has become an important screening test for a variety of fetal and maternal abnormalities. A 33-year-old multiparous white woman had a markedly elevated MSAFP level (140 multiples of the median). Extensive antepartum work-up for fetal anomalies, fetal-maternal transfusion, or maternal etiology revealed no explanation. The patient subsequently delivered a healthy male infant. Pathologic examination of the placenta demonstrated a small, discrete area of choriocarcinoma. Computed tomography showed a solitary pulmonary metastasis. Because the patient did not desire future pregnancies, a total abdominal hysterectomy was performed, followed by four courses of EMA-CO chemotherapy. Her serum hCG levels subsequently became undetectable. Choriocarcinoma of the placenta must be considered in the differential diagnosis of an otherwise unexplained elevated MSAFP level.