Integrating multiple of the median values of serological markers with the risk cut-off value in Down syndrome screening

Abstract

To assess the predictive value of integrating multiple of the median (MOM) with the risk cutoff value for serological screening of Down syndrome. In this retrospective study, women with singleton pregnancies who underwent triple serological screening for Down syndrome were followed, and their screening results and pregnancy outcomes were recorded. The range of MoM value of each indicator was calculated, different protocols integrating various MoM values with the risk cut-off value were compared. A total of 120,269 women with singleton pregnancy were screened and included in the analysis, of those 52 fetuses were confirmed as trisomy-21 by amniocentesis chromosomal karyotyping. Using a risk cut-off value of 1:380, 8,809 samples tested positive and the screen positive rate was 7.32% (8,809/120,269). The normal reference ranges (5-95%) of the MoM value of AFP, β-hCG, and uE3 were 0.60-1.72, 0.43-2.21 and 0.60-1.58, respectively. The detection rate of each screening protocol integrating different MoM percentile values was between 75% and 79%, the positive rate was between 7% and 18%, and the false positive rate was between 7% and 18%. Protocol-6 which combined the screening risk cut-off value and β-hCG MoM ≥ 97.5% percentile is an optimal protocol with a relatively high detection rate (78.8%) and low false positive rate (8.2%). Integrating MoM values of serological indicators can appropriately increase detection rate when interpreting the results of Down syndrome screening.