maternal serum AFP

maternal serum AFP,  human
chorionic gonadotrophin (HCG) and unconjugated estriol
(uE3) in the second trimester was shown to be an effective
screening test for Down syndrome, providing a composite risk
figure taking maternal age into account. When 5% of women
were selected for diagnostic amniocentesis following serum
screening, the detection rate for Down syndrome was at least
60%, well in excess of the detection rate achieved by offering
amniocentesis on the basis of maternal age alone. Serum
screening does not provide a diagnostic test for Down
syndrome, since the results may be normal in affected
pregnancies and relatively few women with abnormal serum
screening results actually have an affected fetus. Serum
screening for Down syndrome is now in widespread use and
diagnostic amniocentesis is generally offered if the risk of Down
syndrome exceeds 1 in 250. Screening strategies include
combinations of first trimester measurement of pregnancy
associated plasma protein A(PAPP-A) and HCG, second
trimester measurement of AFP, HCG, uE3 and inhibition A and
first trimester nuchal translucency measurement.