Serological screening and antenatal diagnosis of patients with Down's syndrome in early pregnancy

Objective To explore the practical value of Down's syndrome screening in early pregnancy.Methods Serum(PAPP-A and free-β-hCG) level of 4 186 pregnant women(at 10~13~(+6)weeks of congestation) were detected by time-distinguished fluorescence immunoassay.Down's syndrome risk value was calculated with Multicalc software,its cut-off value was 1:250.The pregnant women whose risk value was higher than or equal to 1:250 were regarded as to be at high risk and need to receive cordocentesis for fetal karyotype analysis after 18 weeks of congestation.Results 4 186 pregnant women underwent antenatal screening,233 of them were in high risk of Down's syndrome,and the false positive rate was 5.5%.Fetal karyotypes of 138 cases were examined by cordocentesis,Three cases of Down's syndrome(one of them was leaked by diagnosis) and 21 cases with fetal other abnormal chromosome were determined.The detectable rate was 15.2%.There was significant difference in rate of abnormal outcome of pregnant women and fetuses in the two groups(high risk and low risk of Down's syndrome groups)(26.1% and 10.5% respectively,P0.05). Conclusion Serum PAPP-A and free-β-hCG level of pregnant women in the first-trimester were effective index to identify those abnormal fetuses.As combined with antenatal diagnosis,it would be a practical method of preventing congenital defects.