Re‐evaluating diagnostic thresholds for intrahepatic cholestasis of pregnancy: case–control and cohort study

Objective To determine the optimal total serum bile acid (TSBA) threshold and sampling time for accurate intrahepatic cholestasis of pregnancy (ICP) diagnosis. Design Case–control, retrospective cohort studies. Setting Antenatal clinics, clinical research facilities. Population Women with ICP or uncomplicated pregnancies. Methods Serial TSBA measurements were performed pre‐/postprandially in 42 women with ICP or uncomplicated pregnancy. Third‐trimester non‐fasting TSBA reference ranges were calculated from 561 women of black, south Asian and white ethnicity. Rates of adverse perinatal outcomes for women with ICP but peak non‐fasting TSBA below the upper reference range limit were compared with those in healthy populations. Main outcome measures Sensitivity and specificity of common TSBA thresholds for ICP diagnosis, using fasting and postprandial TSBA. Calculation of normal reference ranges of non‐fasting TSBA. Results Concentrations of TSBA increased markedly postprandially in all groups, with overlap between healthy pregnancy and mild ICP (TSBA