PRENATAL DIAGNOSIS OF NEURAL TUBE DEFECTS .3. RE-EVALUATION OF ALPHA-FETOPROTEIN ASSAY

Abstract

.alpha.-Fetoprotein was measured in 2209 human amniotic fluid samples under improved assay conditions. All cases of open neural tube defects had elevated values greater than 5 SD above the mean. The false positive rate based on the 3 SD cutoff was estimated at less than 9.15%. .alpha.-Fetoprotein assays were recommended for all patients undergoing 2nd trimester amniocentesis, optimally between 14-16 wk gestation.