Analysis on medians of maternal serum screening markers at second trimester in China / 中华围产医学杂志

ABSTRACT

Objective To investigate the current situation in application of median levels in second trimester in prenatal screening laboratory throughout China and to understand the methods and importance of quality control.Methods Of those laboratories that participated in the national external quality assessment (EQA) for second trimester maternal serum screening in 2013, 442 submitted the medians for α-fetal protein (AFP), human chorionic gonadotropin (hCG), β-hCG, free β-hCG and unconjugated estriol (uE3) and related information.We categorized the medians according to the platform.There were 170, 210, 31, 26, 13, 11 and nine laboratories using the detection systems from Perkin Elmer, Beckman Coulter, Fenghua, Roche, Darui, Siemens and Abbott, respectively.The method of setting up the medians for each laboratory was analyzed.The number of laboratories, which was the outliers, was determined according to the reported medians on the third day of each week from 14th to 20th gestational weeks.Single sample t-test was applied to compare the result of this study with published results from a multi-center study of pregnant women in China.Results Among all laboratories, 19.0％ (84/442) of the recruited laboratories setup the median on their own.And 4.3％ (19/442) did this with their vendors;76.7％ (339/442) used the default median from the software, among them 97.9％ (332/339) did not verify their medians and 84.3％ (280/332) had no idea of how to do.Medians of AFP and uE3 increased with gestational age, while medians of hCG, β-hCG and free β-hCG decreased in all detection systems.More outliers were found for AFP, free β-hCG and uE3 medians in Perkin Elmer system, which scattered in each gestational age.A higher proportion of AFP in Fenghua system, free β-hCG in Darui system and uE3 in Siemens system were reported [9.5％ (20/210), 13.2％ (12/91) and 23.4％ (18/77), respectively].The medians of AFP and β-hCG using Perkin Elmer platform were compared between this study and the previous multi-center study in Chinese women.The results did not show significant difference in AFP median at 14th and 18th week of gestation (both P ＞ 0.05), while higher medians in AFP at 15th, 16th, 17th, 19th and 20th week of gestation (t=-7.257,-3.204,-5.479,-3.253 and-20.089, respectively, all P ＜ 0.05) and higher β-hCG median at 14th to 20th week of gestation (t=-80.749,-199.779,-142.601, -90.732,-72.984,-47.935 and-39.409, respectively, all P ＜ 0.01) were found in the previous study.Conclusion Most laboratories in our country never verify their medians for second trimester screening program and the medians vary among different settings.