Analysis Of Serum Screening For Down's Syndrome In Early And Middle Period Of Pregnancy And Interventional Antenatal Diagnosis Of 297 Patients

Objective To explore an effective methods of screening the Down's syndrome and severe birth defects through large sample of Down's syndrome screening in the early and middle period of pregnancy.Methods The technology of time-distinguished fluorescence immunoassay was used to detect the serum AFP,freeβ-hCG andμE3 levels of 4762 pregnant women. The high risk pregnant women was calculated with Multical software. These high risk pregnant women were advised to receive amniocentesis or cordocentesis to know the fetal karyotype.Results①The number of pregnant women who underwent antenatal screening is 4762, and the number of followed up women is 2602. The follow up rate is 54%.②2602 pregnant women underwent antenatal screen ing,140 of them were in high risk of Down's syndrome and trisomy 18,17 of them were in high risk of NTD and the number of unusual single index is 547. We finally make sure that there are 10 case of Down's syndrome,4 case of trisomy 18,2 case of trisomy 13,3 case of monosomy, 2 case of per icentr ic inversion,3 case of chromosome missing,5 case of genet ic polymorphism,2 case of thalassemia,1 case of anencephaly,1 case of inborn dropsical nephritis.③The sensitivity and specificity and false positive rate and false negative rate of the allied screening Dowm's syndrome of serum marker are 60%,94.95%,5.05%,40%; The sensitivity and specificity and false positive rate and false negative rate ofμE3 as the single index are 50%,90.64%,9.36%,50%; The sensitivity and specificity and false positive rate and false negative rate of AFP as the single index are 40%,91.49%,8.51%,60%; The sensitivity and specificity and false positive rate and false negative rate of freeβ-hCG as the single index are 10%,91.09%,8.91%,90%.④The sensitivity and specificity and false positive rate and false negative rate of the allied screening trisomy 18 of serum marker are 25%,99.83%, 0.17%,75%;The sensitivity and specificity and false positive rate and false negat ive rate ofμE3 as the single index are 50%,90.54%,9.46%, 50%; The sensitivity and specificity and false positive rate and false negat ive rate of AFP as the single index are 75%,91.47%,8.53%,25%; The sensitivity and specificity and false positive rate and false negative rate of freeβ-hCG as the single index are 75%,96%,4%,25%.⑤TheμE3 diagnostic point is≤0.733MoM, it can find 50% Dowm's syndrome, the false positive rate is 9.36%; The AFP diagnostic point is lower than 0.6 MoM, it can find 40% Dowm's syndrome, the false positive rate is 8.51%; The freeβ-hCG iagnostic point is lower than 0.4 MoM, it can find 75% trisomy 18,the false positive rate is 4%; The freeβ-hCG iagnostic point is higher than 1.7MoM, it can find 50% trisomy 21,the false positive rate is 21.9%. If the false positive rate is 5%, The freeβ-hCG iagnostic point is higher than 3. OMoM, it can find 10% Dowm's syndrome.Conclusions The serum AFP,freeβ-hCG andμE3 levels of pregnant women are more effect ive in screening trisomy fetus than single index. The women whose single index are positive are advised to receive amniocentesis or cordocentesis. As combined with antenatal diagnosis it would be a practical method of preventing the congenital defect of fetus.