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INTRODUCTION: Practice guidelines utilize absolute bile acid levels to diagnose intrahepatic cholestasis of pregnancy (ICP) or to determine its severity, but the normal reference range varies by laboratory. We sought to evaluate variation in total bile acid assays by laboratory, testing method, and fasting state. METHODS: Using a search engine, we compiled a list of laboratories located within North America, the United Kingdom, and Australia. We obtained laboratory-specific information on bile acid assays, including testing method, reference range, and fasting requirements. Reference ranges were evaluated in relation to ICP severity thresholds (40 or 100 micromoles/L). RESULTS: We identified seven laboratories with total bile acid assays: four in the U.S., one in Canada, one in the U.K., and one in Australia. Three labs also offered a fractionated assay (ARUP, Lab Corp, Quest). Depending on the test employed, the upper limit of normal for total bile acids ranged from 6.8 to 19.0 micromoles/L. Assay methods included chromatography/mass spectrometry, quantitative enzymatic, and spectrophotometry. Fasting was preferred or required in 10 of 11 assays—either overnight, 8 hours, 12–14 hours, or duration unspecified. Utilizing ICP severity thresholds, a total bile acid level greater than 40 micromoles/L or 100 micromoles/L was 2–6 times or 5–15 times the upper limit of normal, respectively, depending on the assay used. CONCLUSION: Multiple bile acid assays are available, but the normal reference range varies due to assay methodology and fasting recommendations. Thus, caution is warranted if a definitive bile acid is utilized to define disease severity or perinatal risk. [ABSTRACT FROM AUTHOR]