Efficacy of maternal serum PAPP-A detection in first trimester combined with dual-marker screening test in second trimester in screening for Down's syndrome and open neural tube defect

  Objective  To assess the efficacy of maternal serum pregnancy associated plasma protein-A (PAPP-A) in first trimester combined with detections of maternal serum alpha fetoprotein (AFP) and free β subunit of human chorionic gonadotropin (free β-hCG) in second trimester for screening Down syndrome (DS) and open neural tube defect (ONTD).

  Methods  We analyzed clinical data on 46 089 pregnancies in prenatal screening centre of Yuhang district of Hangzhou Maternity and Child Health Care Hospital in Zhejiang province from July 1, 2014 to December 31, 2016, retrospectively. PAPP-A was detected in first trimester and AFP and free β hCG were detected in second trimester for DS screening. The detection results of first and second trimester were combined as a triple-marker of screening to calculate the risk rate of DS and ONTD. We followed pregnancy outcomes and karyotype analysis of amniocentesis to make a definite diagnosis.

  Results  The screening sensitivity was 68.30%, 100%, and 83.33% for the test in first trimester, second trimester, and of triple-marker, without significant difference (χ² = 0.540, P = 0.463). Both screening results of dual-marker in second trimester for one case and triple-marker test for 6 cases were low risk of ONTD and the sensitivity of the tests was 0%.

  Conclusion  Triple-marker screening test is better than dual-marker screening test in second trimester; however, the difference is not significant. Serum screening test is not applicable for the screening of ONTD.