Prenatal screening in the first trimester of pregnancy

Prenatal screening for fetal abnormalities is an accepted part of modern obstetric management. Improvements on current screening procedures need to address increased diagnostic efficacy and earlier diagnosis. This study evaluates the diagnostic efficacy of PAPP-A and F beta-hCG in the detection of first trimester pregnancy abnormalities, including Down syndrome (DS). Of 731 pregnant volunteers: obtained from a mature age population undergoing chorionic villus sampling (CVS), 17 DS and 11 compromised (six numerical (excluding sex chromosome) aneuploidies, five spontaneously failed) pregnancies were detected. Application of an algorithm, which combines PAPP-A and F beta-hCG levels with maternal age, detected 66.6 per cent of DS pregnancies for a five per cent false positive rate. Similarly, for a 1.2 per cent recall rate: 72.7 per cent of compromised pregnancies were detected. This report supports the notion that prenatal screening at 9-12 weeks of pregnancy is achievable with PAPP-A and F beta-hCG quantitation. Whereas mid-gestational screening target-led the detection of fetal abnormalities, screening earlier in pregnancy will detect other pregnancy-related abnormalities, in addition to aneuploidy. (C) 1998 John Wiley & Sons, Ltd.