Quality specifications for S-AFP and S-HCG-beta determinations for screening of fetal abnormalities

High levels of maternal serum alpha-1-fetoprotein (S-AFP) are associated with fetal structural abnormalities like neutral tube defects and congenital nephrosis. It has a very high detection rate when used for screening of these diseases. On the other hand, the low levels of maternal S-AFP act as a marker of many fetal chromosomal aberrations. The detection rate of S-AFP alone for the screening of Down's syndrome is low. Wald et al. have shown that the addition of the determination of maternal serum chorionic gonadotrophin (S-HCG-beta) to S-AFP analysis, and using a computer program for risk estimation increases the detection rate for Down's syndrome to about 57% with a false positive rate of 5%. In this study we present the results of our screening program for structural fetal defects and chromosomal aberrations in Eastern Finland, and describe the standardization and quality control of maternal serum AFP and HCG-beta analysis.