A Perspective Study Of Different Serum Prenatal Screening System For Chromosomal Disorder In Second-Trimester Pregnancy

Objective:To compare the performance of different serum prenatal screening systems based on Time-Resolved Fluorescence ImmunoAssay and Chemiluminescence ImmunoAssay and obtain gestational age-specific Medians for local population.Material and Method:About6600serum sample of second-trimester singleton Chinese pregnancy were collected from prenatal screening center of Haidian Maternal and Child Care Center from September2008to January2009. AFP, free β-hCG and uE3were measured by DELFIA system and AFP and total β-hCG were measured by Abbott system. Median of Medians (MoM) of each marker and risk value of double test or triple test were calculated by corresponding Calculation Software. Follow up for pregnancy outcome. Compare the performance of these two systems and MoM distribution. Descriptive statistic and regression analysis were used to obtain gestational age-specific Medians for local population.Result:1. About6600serum sample of second-trimester singleton Chinese pregnancy were collected, all measured by DELFIA system and5383of which were measured by Abbott system. By May30th2009, follow-up of4245cases were obtained,462cases lost, follow-up rate was90.2%. There are3cases of Down Syndrome,5cases of other chromosomal abnormality and1case of Neutral Tube Defects.2. The Detective Rate of DELFIA system triple test and double test were66.7%and33.3%, respectively. The False Positive Rate was5.26%and4.01%.3. For Abbott system, Median MoM of AFP and total β-hCG was0.700using Software Gestational Medians. Replaced by regressed medians of this study, Median MoM of AFP and total β-hCG were0.999and1.009. The distributions of software calculated MoM and re-calculated MoM were significant different.4. Replaced software Medians by regressed Medians of this study, re-calculated risk value and set1/350as Cut-off, the Detective Rate and False Positive Rate of Abbott system double test were33.3%and4.26%, respectively.Conclusion:1. DELFIA system triple test was better than double test.2. Abbott software Medians were different from Medians of local Chinese population. Cut-off value of1/250was not suitable for screening systems based on CLIA. Medians of each screening markers of local Chinese population should be established through large scale study.3. Using regressed Medians of this study, the performance of Abbott system double test was similar to that of DELFIA system double test.4. Abbott system double test is appropriate for most developing areas of China. DELFIA system triple test is more suitable for major cities and large prenatal screening center.