The aim of the study is to investigate the efficiency of the second-trimester biochemical screening, with maternal serum
alpha-fetoprotein (MS-AFP) and free b-subunit of human chorionic gonadotropin (free b-hCG), during the ten-year
period. The study included 11,292 of pregnant women between the 15th and 18th gestational week, who underwent screening
from November 1996 to December 2006. The risk for trisomy 21 and trisomy 18 were calculated by computer software,
based on a model which generated the final risk for fetal aneuploidies from the pregnant woman’s a priori age risk
and the likelihood ratio of the distribution of the biochemical markers, according to the second-trimester gestation. With
the cut-off value of the final risk 1:250, the detection rate for trisomy 21 was 75% (21/28). In women less than or equal to
35, the detection was 57.1% (8/14) and 92.9% (13/14) in those over 35 years, respectively. The detection rate of trisomy 18
was 50% (2/4). The results confirmed that the implementation of double-test, as non-invasive screening for fetal aneuploidies,
should be accepted as a complementary method of antenatal care
