Etiologic significance of anatomic variations in the main intrahepatic bile ducts in hepatolithiasis

Abnormal union of intrahepatic bile ducts has been suggested as a possible etiologic factor in the occurrence of intrahepatic stones. A series of 241 patients were examined by direct cholangiography, and anatomic variations in the intrahepatic bile ducts were classified into four types: Type A-1, normal union having a true right hepatic duct; Type A-2, absence of a right hepatic duct, with a trifurcation; Type B, posterior segmental duct draining into left hepatic duct; Type C, anterior segmental duct draining into left hepatic duct. The most dominant type was Type A-1, which occurred in 58.3 to 66.0 per cent of the cases, followed by Type A-2 with 12.5 to 19.8 per cent. Type B showed the lowest incidence, occurring in 4.5 to 10.4 per cent. No statistical difference existed in the distribution of the type of union of intrahepatic bile ducts on the one hand and the presence or absence of intrahepatic stones on the other. Thus, anatomic variations in the main intrahepatic bile ducts do not seem to be associated with hepatolithiasis, and their etiologic significance seems to be unlikely.