Comparison Of Two Different Strategies In Prenatal Screening For Down Syndrome

Objective To assess and compare the effectiveness of two different strategies （the integratedscreening and second trimester screening） in prenatal screening for trisomy-21（Down syndrome,DS）,in order to find more effective screening programs.Methods1760cases of pregnant women received B ultrasound to detect the fetal necktranslucency thickness （NT） when they were9¹3⁺⁶weeks), detect the level of PAPP-A, Free-β-HCG, in mid-term pregnancy (15weeks to19⁺⁶weeks) detect the level of AFP, Free-β-hCG, uE3,calculate the occurrence of trisomy-21and trisomy-18, high risk of trisomy need to have prenataldiagnosis and pregnancy outcome was followed up.Results Complete screening and pregnancy outcome data of1632cases were obtained.26cases were integrated screening positive.High risk cases received fetal karyotype analysis,detectingabnormal fetal chromosome in4cases,including2cases of trisomy-21,1cases of trisomy-18,1cases of46，XY，inv（9）.In the second trimester screening group, there were1330cases of DSpositive and138cases of ES positive. High risk cases received fetal karyotype analysis,detecting20cases of trisomy-21,4cases of trisomy-18.The false positive rate（FPR） of two strategies were1.47%、3.27%.（χ²=16.44，P﹤0.05），the Positive Predictive Value（PPV） of two strategieswere7.69%、1.50%.（χ²=6.12，P﹤0.05）.Conclusion There were statistically significant difference between two strategies, integratedscreening has a higher positive predictive value, lower false positive rate, is a more effectivescreening models, if conditions permit, we recommend to use integrated screening.