[Trisomy-21 screening using AFPplus in the eastern part of Switzerland]

Two years after introduction of maternal serum screening for Down's syndrome in German-speaking Switzerland, based on measurements of alpha-fetoprotein, unconjugated estriol and total beta-HCG, results were analyzed of the two cytogenetic laboratories in Zurich and of a separate collective of the Department of Obstetrics at the University of Zurich. In a total of 489 cases with increased risk for Down's syndrome (> or = 1:380 at term) 19 (1:26; approximately 4%) had an abnormal fetal karyotype from which 16 had a trisomy 21. 13 out of these 16 mothers were aged below 35 years. Thus, after ultrasound, maternal serum screening detects the highest percentage of fetuses with chromosomal abnormalities. At the Department of Obstetrics 2962 serum screening tests were performed during a period of 2 1/2 years. 14.6% of the women were > or = 35 years old, 7.6% showed increased risk and 14 fetuses had an abnormal karyotype including 10 with Down's syndrome. 7 of these 10 were detected by the serum test. Nevertheless, the limited sensitivity of serum screening, its limitation predominantly to detection of fetuses with Down's syndrome and the rather late stage of screening, make effective first trimester screening mandatory.