STUDY OF THE EFFICIENCY OF SCREENING FOR TRISOMY-21 BASED ON MATERNALSERUM LEVELS OF AFP AND HCG COMBINED WITH MATERNAL AGE

We evaluated second trimester human chorionic gonadotropin (hCG) and a lpha-fetoprotein (AFP) concentrations for 5,787 maternal serum samples between 15 and 19 weeks' gestation and compared them with maternal ag e data to evaluate the efficiency of a combined protocol in the predic tion of mid-trimester risk for trisomy 21, The hCG and AFP measurement s were performed using kits developed in our tenter, and the probabili ty risk calculation was similar to that of Crossley (Prenatal Diagnosi s 1991; 11:83-101), With a cut-off value of 1:200, we obtained a 75% d etection rate and a false-positive rate of 7.2%, The individual values of hCG and AFP in abnormal outcomes were reviewed and confirmed that the hCG value used alone provides a greater predictive value than othe r biochemical markers, Of nine cases with fetal aneuploidy, five had h CG values above 2 multiples of the median (55.5%), We conclude that th e introduction of this combined protocol efficiently measures the risk for Down's Syndrome in the second trimester of pregnancy.