Assessment of biliary tree anatomy and its clinical implications

Anatomical variations in the intrahepatic duct (IHD) and cystic duct (CD) are common, and their accurate identification is essential for preoperative planning. The present study aimed to assess the prevalence of biliary ductal variations using magnetic resonance cholangiopancreatography (MRCP), to explore the association between IHD and CD and to evaluate potential associations with common biliary disorders. In the present retrospective study, a total of 259 patients, who were referred for MRCP due to various biliary-related clinical indications, including biliary stones, cholecystitis and obstructive jaundice, between January 2019 and December 2023, were included. Variations of the IHD and CD were classified based on imaging findings. Associations with biliary stones, cholecystitis and obstructive jaundice were assessed using the χ² test and univariable and multivariable logistic regression analyses. IHD variations were identified in 38.6% of cases, which was most commonly attributed to a trifurcation pattern (22%), followed by drainage of the right posterior duct into the common hepatic duct (8.5%) or the left hepatic duct (7.7%). CD variations were observed in 36.7% of cases, which were most commonly medial anterior (17.8%) or posterior (18.9%) spiral insertions. A significant association was found between IHD and CD variations (P=0.010). CD variations were also associated with a higher prevalence of biliary stones (P=0.023) and cholecystitis (P=0.048). In multivariable analysis, IHD variation [adjusted odds ratio (aOR)=1.95; 95% confidence interval (CI), 1.14-3.35; P=0.015] and biliary stones (aOR=1.79; 95% CI, 1.03-3.12; P=0.041) were independent predictors of CD anatomical variants. In conclusion, anatomical variations of the IHD and CD were common and strongly associated. Recognizing these variants could be essential for preoperative planning and aid in anticipating complications, particularly given their association with stone formation and cholecystitis.