1Hamida Gohar, 1Amal Balbaa, 1Heba Arnaout and 2Omima Idris.
1Microbiology & Immunology and 2Obstetrics & Gynaecology Departments, Faculty of Medicine, Cairo University, Egypt.
The purpose of this study was to assess the utility of triple-marker screening for Down’s syndrome. Two hundred and seventeen pregnant females between 15 and 20 weeks gestation were subjected to triple marker screening test. Serum samples were analyzed for alpha fetoprotein (AFP), human chorionic gonadotrophin (HCG), and unconjugated estriol (uE3). By using the median values of these tests plus maternal age, a specific risk for trisomy 21 was calculated with a specific computer program. A test was considered positive if the calculated risk was £ 270. Using the three markers, the initial screen-positive rate was 30% (65 women). Amniocentesis was offered to all of them. Three ascertained cases of trisomy 21 were identified in the screen positive patients. Two of the three cases of trisomy 21 were > 35 years old. The false positive rate was 28.5%. Omitting unconjugated estriol would have resulted in detection of only 2 of the 3 trisomy 21 cases while the false positive rate would have remained the same. Addition of unconjugated estriol resulted in an increased detection rate of trisomy 21 with no change in the false positive rate.