The relationship between first and second trimester biochemical parameters used to screen down syndrome and intrahepatic cholestasis of pregnancy

Objective: To assess the role of first and second-trimester screening biomarkers pregnancy-associated plasma protein-A(PAPP-A), free beta-human chorionic gonadotropin(free ß-hCG), estriol, alpha-fetoprotein and total β-hCG in the early diagnosis of intrahepatic cholestasis of pregnancy (ICP). Materials and Methods: Patients with ICP admitted to Mersin University Hospital for delivery between 2015 and 2019 and had first and second-trimester aneuploidy screening tests performed in the same facility were retrospectively assessed. Randomly 60 pregnant women without comorbid conditions during the same period were included as controls. Data regarding demographic characteristics, laboratory values including free ß-hCG and PAPP-A in first-trimester screening and total ß-hCG, estriol and alpha- fetoprotein in second-trimester screening were compared. Results: There were 46 eligible patients with ICP. In first trimester screening, it was found that PAPP-A MoM was significantly lower (0.89±0.55 vs. 1.94±0.73; p=0.035) while free ß-hCG MoM was significantly higher in ICP group when compared to controls (1.84±0.59 vs. 0.99±0.47; p=0.018). In second trimester screening, no significant difference was detected in aneuploidy markers between groups. For prediction of ICP development, first trimester free β-hCG >1.44 MoM was found to have a sensitivity of 50%, a specificity of 80% and positive and negative predictive values of 33% and 88.9% respectively. Similarly first trimester PAPP-A values <1.075 MoM was found to have 80% and 75% sensitivity and specificity with positive and negative predictive values of 75% and 44% respectively. Conclusion: Low PAPP-A MoM value and elevated free ß-hCG in first trimester seem to be associated with ICP development.