ABSTRACT
To evaluate the triple screening test [using AFP, beta-HCG and uE3] in prenatal diagnosis of Down syndrome through comparing the results of the test with the outcome of pregnancy. We will also compare these results with the results of the double test [using AFP and beta-HCG] or MSAFP test to evaluate the value of combining beta-HCG, alpha-fetoprotein [AFP] and unconjugated estriol with maternal age in this three-analyte maternal serum screening program for Down syndrome. This study was conducted on 50 pregnant women, 35 years or older. Their gestational age ranged from 14th to 19th week of pregnancy detected through 1st day of last menstrual period. Blood samples were taken from them for measurement of alpha-fetoprotein, HCG and unconjugated estriol. Risk ratio was calculated for Down syndrome detection using three protocols: MSAFP alone, MSAFP and HCG, MSAFP, HCG, and unconjugated estriol [triple test] using Prisca software [DPC, France]. The [cut-off] median MoM values in pregnancies with Down syndrome were 0.73 [AFP], 2.02 [beta-HCG] and 0.74 [uE3]. After labour, the newborns of selected women for the study were evaluated clinically for diagnosis of Down syndrome. The results of all tests done before labour are compared with the clinical evidence of cases to evaluate them. The detection rate of triple test, double test, MSAFP test was 75%, 50%, 25% respectively. The false positive rate was 40%, 75% and 94% respectively. The correlation coefficient between each test and actual outcome of pregnancy was 0.626 for triple, 0.267 for double and 0.146 for MSAFP test. Using cut-off value 1:190 kept the same detection rate for triple test and lowered the false positive rate to 25%. Triple screening test using AFP, HCG and uE3 has the upper hand over MSAFP and double test in detection of Down syndrome as it has the highest detection rate and lowest false positive rate. The value of correlation coefficient means that other factors or analytes need to be added to improve the detective power of the tests. It is strongly recommended to lower the cut-off value to be 1:190 instead of 1:270. These results need to be evaluated on a more large scale