Variations in the vascular and biliary structures of the liver: a comprehensive anatomical study

Purpose: Vascular structures of the liver and the bile ducts are crucial during liver transplantation or liver resection surgery. Here, we report on variations in the vascular structures and bile ducts of 200 patients. Materials and Methods: We reviewed magnetic resonance cholangiopancreatographic and multiple-detector computed tomographic data. Results: Michels type 1 was detected in 54% of the patients. The other most common variations were, respectively, Michels type 5 (13%) and type 2 (11%). Unclassified variations were defined as Michels type 11; 5% of patients were in this group. Type 1 variations in the hepatic portal vein were detected in 76% of our study group. Other common variations were type 2 (9%) and type 3 (8.5%). The left and intermediate hepatic veins united to become a single vein and then joined the inferior vena cava in 64% of the patients. The right, intermediate, and left hepatic veins joined the inferior vena cava separately in 36% of the patients. Type A, which represents the classic anatomy of the bile duct, was observed in 51.5% of our patients. Type C1 and type B were detected in 15% and 12% of patients, respectively. Conclusions: We describe vascular and biliary variations in the livers of our patients.