The value of nipt combined with serum cell-free dna, estriol, afp, and -hcg levels in the recognition of trisomy 21 and 18 in the second trimester

Background: This study aimed to evaluate the clinical application value of noninvasive prenatal testing from DNA (NIPT) and serum screening for screening in detecting fetal trisomy 21 and 18.Methods: As a retrospective analysis, we collected data from 1383 women (singleton pregnancy) who underwent serum screening and noninvasive prenatal testing from DNA (NIPT) in our department from May 2015 to September 2017 and calculated the diagnostic value of the two methods.Results: In 1383 cases, the sensitivity of serum screening to trisomy 21 and 18 was 76.9%, specificity 74.7%, PPV 2.9%, NPV 99.7%, and AUC 0.758 (95% CI: 0.625- 0.891). The sensitivity of noninvasive prenatal testing from DNA (NIPT) to trisomy 21 and 18 was 100%, specificity 99.8%, PPV 81%, NPV 100%, and AUC 0.999 (95% CI: 0.000-1.000).Conclusion: Serum screening can detect high-risk preg-nant women in time, but the incidence of false positives and negatives is high; the accuracy of noninvasive prenatal testing from DNA (NIPT) is high, which can effectively reduce the rate of defective babies.