Rapid Diagnosis of Intrahepatic Cholestasis of Pregnancy (ICP): Validation of an Automated Enzymatic Total Bile Acid Assay and Assessment of Ursodeoxycholic Acid Impact on Bile Acid Profiles in an ICP Cohort

BACKGROUND: Intrahepatic cholestasis of pregnancy (ICP) requires timely diagnosis to guide management, including initiation of ursodeoxycholic acid (UDCA) and delivery planning. LC-MS/MS provides fractionated bile acid profiles but has a turnaround time (TAT) of approximately 1 week, delaying treatment. Enzymatic total bile acid (TBA) assays offer faster results but measure all bile acids collectively, which some have reported can be impacted by UDCA treatment. METHODS: We validated the Diazyme enzymatic TBA assay on a Roche Cobas analyzer, assessing analytical measurement range, reference interval, precision, and accuracy vs LC-MS/MS. The comparison cohort included samples from 100 pregnant patients (median age 31 years; gestational age 34 weeks) presenting with pruritus and suspected of ICP. A secondary analysis examined UDCA and tauroursodeoxycholic acid in a UDCA-detectable subset. TAT was evaluated retrospectively in 971 specimens. RESULTS: We verified the assay's analytical measurement range of 1 to 180 µmol/L and reference interval of