MATERNAL SERUM AND AMNIOTIC-FLUID ALPHA-FETOPROTEIN IN PREGNANCIES WITH TRISOMY AND OTHER CHROMOSOMAL-ABNORMALITIES

Objective: The aim of this study was to investigate the association be tween low maternal serum alpha-fetoprotein (MSAFP) and amniotic fluid alpha-fetoprotein (AFAFP) and fetal chromosomal abnormalities includin g Down's syndrome. Methods: A retrospective review of 27 pregnancies w ith chromosomal abnormalities included 11 fetuses with Down's syndrome , four with trisomy-18 and 12 with other chromosomal abnormalities. MS AFP and AFAFP levels were studied between 16 and 24 weeks' gestation. Results: The MSAFP median value of Down's syndrome is 0.7 MoM (multipl e of median), of trisomy-18 it is 0.45 MoM, and of other abnormalities it is 0.79 MoM. The AFAFP median value of Down's syndrome is 0.55 MoM , of trisomy-18 it is 1.0 MoM, and of other abnormalities it is 1.0 Mo M. The mean values of MSAFP (0.72 +/- 0.26 MoM) and AFAFP (0.63 +/- 0. 23 MoM) with Down's syndrome were significantly lower than controls. T he mean values of MSAFP with trisomy-18 (0.51 +/- 0.33 MoM) and other abnormalities (0.80 +/- 0.25 MoM) were also significantly lower than c ontrols. There was no difference in the AFAFP mean values with trisomy 18 (1.01 +/- 0.09 MoM) and other abnormalities (1.05 +/- 0.22 MoM) wh en compared with controls. Conclusions: Screening patients with low MS AFP values could detect 20-30% of fetuses with Down's syndrome. Patien t with low MSAFP should be counseled that not only Down's syndrome, bu t other abnormalities may be considered.