AMNIOCENTESIS RATE AND THE DETECTION OF DOWN-SYNDROME AND OTHER CHROMOSOMAL-ANOMALIES IN ISRAEL

We investigated the contribution of different screening criteria to th e prenatal detection of Down syndrome (DS) as well as other chromosoma l anomalies in the Jewish population in Israel during 1990 and 1992. T here was a significant decrease (P<0 . 03) in the incidence of DS live -births during 1992 (40:78 442) compared with 1990 (69:73 751) which p aralleled a marked increase in total prenatal testing and in DS cases detected prenatally. Private laboratories, which perform amniocenteses mostly for women with a low risk of DS and without genetic counsellin g, had a significantly lower detection rate (1:917) compared with that of the genetic institutes, which following genetic counselling test b oth women greater than or equal to 37 years of age (1:91) and women yo unger than 37 years (1:113). The detection of chromosomal anomalies ot her than DS was less affected by the reason for amniocentesis. Amnioce ntesis indicated by maternal serum marker screening of women younger t han 37 years identified a greater number of chromosomal anomalies othe r than DS than amniocentesis based on age (greater than or equal to 37 years) alone (111:9604 versus 94:9810; P<0 . 06). Prenatal detection of DS is most effective when the indication for amniocentesis follows genetic counselling. The increasing use of maternal serum marker scree ning leads to a significant improvement in the positive detection rate of chromosomal anomalies other than DS in young women.