MATERNAL SERUM-FREE BETA-HCG SCREENING - RESULTS OF STUDIES INCLUDING480 CASES OF DOWN-SYNDROME

The median maternal serum free beta human chorionic gonadotropin (hCG) multiple of the median (MOM) of 480 Down syndrome cases in the second trimester was 2.64, significantly greater than the reported median MO M of intact hCG (p<0.0001). In 234 of these cases from retrospective a nd prospective studies, the effectiveness of maternal serum free beta hCG was evaluated in combination with alpha-fetoprotein (AFP) and mate rnal age in second-trimester Down syndrome screening. Down syndrome de tection in the gestational age range of 14-16 weeks was 82 per cent. I n all gestational weeks (14-22), a 77.7 per cent Down syndrome detecti on rate was achieved. In prospective screening of 44272 patients under the age of 35 years, 69 per cent of Down syndrome cases were detected (73 per cent in gestational weeks 14-16). The false-positive rate for the prospective study was 3.8 per cent. The use of free beta hCG comb ined with maternal serum AFP and maternal age-related risk for Down sy ndrome in a screening population (i.e., women under 35 years) yields a n improved detection efficiency over other protocols.