Objective: To establish reference values for bile acids and bilirubin levels in amniotic fluid and to assess their correlation to amniotic fluid digestive enzymes in normal pregnancies as a foundation for future diagnostic studies.
Methods: This prospective cross-sectional study included pregnant women with a singleton pregnancy at 17-23 weeks' gestational age who underwent amniocentesis. Levels of bile acids, total bilirubin, direct bilirubin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, lactate dehydrogenase, and γ-glutamyltransferase were assessed. Gestational age reference ranges were established for bile acids and bilirubin levels.
Results: A total of 133 women were recruited. The most common indication for amniocentesis was advanced maternal age. The 5th, 50th, and 95th percentile of bile acids for the entire cohort was 1.3, 7.2, and 30.8 µM, respectively. There was no significant change in bile acid levels throughout gestational weeks. Mean, standard deviation, and median values for all hepatobiliary enzymes were calculated. On regression analysis a significant positive correlation between bile acids and GGT was found.
Conclusion: Reference values for amniotic fluid bile acids and bilirubin at 17-23 weeks in normal pregnancies were established. The significant correlation between bile acids and GGT, combined with the direct biological relevance of bile acids in biliary pathology, suggests potential utility as complementary or alternative biomarkers in pregnancies complicated with non-visualization of the fetal gallbladder.
S. Karger AG, Basel.