Studies of prenatal screening and diagnosis for Down′s syndrome in second trimenster

Objective To study the important role of prenatal screening and diagnosis for Down′s syndrome in second trimenster to interfere birth defects.Methods The value of AFP and β-HCG in the serum was detected in 3 327 pregnant women at about 14th～20th weeks gestation with ELISA and calculate their risk coefficient with professional software.Karyotyping on cultured cells in amniotic fluid was carried out on pregnancie at high risk of Down′s syndrome.Gene diagnosis and FISH were employed to confirm the result of karyotyping.B-ultrasonography was offered to women at high risk of carrying neural tube defect(NTD)fetus.Results In 3 327 pregnant women,212 cases(6.37%) were high risk,160 cases(4.81%) were at high risk for Down′s syndrome.With further prenatal diagnosis,4 cases were detected in 119 high risk pregnancies with chromosome disease.With B-ultrasonography detection,only one fetus was detected with NTD in the 36 cases with NTD high risk.4 of 16 cases at high risk of trisomy 18 and trisomy 13 accepted amniocentesis,and no abnormality was found.Conclusion Prenatal screening and prenatal diagnosis play an important role in the prevention of Down′s syndrome and other congenital abnormality.