ELEVATED MATERNAL SERUM ALPHA-FETOPROTEIN LEVELS - WHAT IS THE RISK OF FETAL ANEUPLOIDY

OBJECTIVE: Our purpose was to present the findings of a project to det ermine the efficacy of including routine fetal karyotyping in the inve stigation of an elevated maternal serum alpha-fetoprotein concentratio n. STUDY DESIGN: Targeted ultrasonographic examinations were performed in 658 patients with elevated maternal serum cu-fetoprotein levels. T he scans were normal in 557 women, of whom 427 consented to amniocente sis; 435 fetuses were karyotyped. In the 101 patients with abnormal ul trasonographic examinations 75 had fetal karyotyping. RESULTS: In the 435 fetuses with normal scans, two had karyotypic anomalies, a 47,XYY and an inherited balanced translocation. Three fetuses with normal kar yotypes and high amniotic fluid alpha-fetoprotein levels had congenita l nephrosis. In the 101 patients with abnormal scans, 75 fetuses were karyotyped. There were four aneuploidies. Among the 26 patients with a bnormal scans who declined amniocentesis one fetus with multiple anoma lies was karyotyped after delivery and triploidy was discovered. CONCL USIONS: These results provide little justification for including fetal karyotyping in the investigation of elevated maternal serum alpha-fet oprotein when the targeted ultrasonographic examination is normal. Whe n it is abnormal, selective rather than routine karyotyping is more ap propriate.