Biliary and Pancreatic Ductal Anatomical Variations in a South Indian Population: An MRCP Based Analysis and its Clinical Applications

Introduction: The biliary and pancreatic ductal systems exhibit considerable anatomical variability, which holds significant surgical and clinical relevance. Accurate preoperative delineation of these variations helps prevent inadvertent injuries during hepatobiliary or pancreatic procedures. Magnetic Resonance Cholangiopancreatography (MRCP) serves as a safe, noninvasive modality for evaluating ductal anatomy with high diagnostic accuracy. Aim: To determine the prevalence of anatomical variations in the biliary tree, cystic duct, and pancreatic duct in a South Indian population using MRCP. Materials and Methods: A cross-sectional study was conducted at a Chettinad Hospital and Research Institute, Kelambakkam, Chennai, Tamil Nadu, India from January 2023 to July 2025. A total of 345 MRCP studies were reviewed retrospectively, of which 45 were excluded due to poor image quality. The remaining 300 studies were analysed independently by two senior radiologists, with discrepancies resolved by consensus. Variations of the right and Left Hepatic Ducts (LHD) were classified according to Lyu SY et al., while cystic duct and pancreatic duct morphology were evaluated based on their course and insertion patterns. Data were analysed using Statistical Package for Social Sciences (SPSS) version 23. Results: Among 300 patients (mean age 44.3 years), the most common Right Hepatic Duct (RHD) variant was Type A1 (48%), followed by A2 (30%). LHD anatomy was predominantly Type B1 (82%). Right lateral insertion of the cystic duct was the most frequent variant (62%), while low insertion was noted in 15% of cases. The mean CBD diameter was 6.5±3.2 mm, and the mean Main Pancreatic Duct (MPD) diameter was 2.1±1.2 mm. The descending type of pancreatic duct was observed in 78% of patients, and pancreatic divisum was identified in two cases. No statistically significant association was found between ductal variations and gender (p-value >0.05, using chi-square test). Conclusion: MRCP effectively characterises hepatobiliary and pancreatic ductal variations, many of which bear important surgical and endoscopic implications. Understanding these variants is essential for safe operative planning, particularly in donor hepatectomy, laparoscopic cholecystectomy, and Endoscopic Retrograde Cholangiopancreatography (ERCP). Further multicentric studies across India are recommended to improve demographic representation.