Screening Clinical Practice Analysis of Down′s Syndrome in the Middle Period Pregnancy Among 3275 Cases

Abstract

Objective To explore the practical value of Down's screening in the middle period pregnancy in detecting congenital birth defect and predicting the outcome of pregnancy. Methods Select 3275 cases of pregnant women who received the second trimester (gestation of 14 to 20 weeks of gestation) were inspected by the maternal serum screening during December 2006 to December 2008. Alpha fetoprotein AFP and Free β-hCG in mother's blood serum were inspected by automatic chemical radiation method, meanwhile, combining the age, body mass index, gestational age and whether or not twins, diabetes mellitus history, smoking history to count the risk probability of Down's syndrome, Edwards' syndrome and neural tube defects by using the DS-specific risk analysis software were the maternal serum screening. The pregnant women whose value at high risk were diagnosed by the ultrasonography, amniotic fluid or cord blood paracentesis(In this study, the procedures followed to comply with the ethical standards developed by the hospital IRB, were approved by the Committee, and the clinical research informed consent were signed by the subjects.). Results The fetal defects' screening total positive rate of the serum markers during the second trimester in this group was 9.22%(302/3275), the true positive rate was 1.74%(57/3275), the false negative rate was 0.49%(16/3275), the detection rate was 78.1%(57/73). The positive rate of the Down's screening in this group was 7.80%(261/3275), the true positive rate was 0.15%(6/3275), the false negative rate was 0.09%(3/3275). The positive rate of the Edwards' syndrome screening was 0.73%(24/3275), the true positive rate was 0.12%(4/3275), the false negative rate was 0%. The positive rate of the neural tube defects screening was 0.52%(17/3275), the true positive rate was 0.15%(5/3275), the false negative rate was 0.06%(2/3275). Two cases of chromosome abnormality were both positive on screening of the serum markers in this group. A total of 53 cases were other various kinds of malformation, among them, 42 cases were positive on maternal serum screening. Conclusions Two associated biochemical maternal serum screening of pregnant women during second-trimester were effective indexes to screen abnormal fetus and predict outcome of pregnancy and fetus, combined with ultrasonography, which would be a practical method of preventing congenital defect. Key words: prenatal screening; Down syndrome; Edwards' syndrome; neural tube defects