Anatomic variants of intrahepatic bile ducts in Thais

Background: The progress in development of hepatobiliary surgical procedure has made understanding of the normal and variations of bile ducts important.

Objective: We determined anatomical variation of intrahepatic bile ducts in detected on magnetic resonance cholangiopancreatography (MRCP) at King Chulalongkorn Memorial Hospital in Thai people in order to perform interventional procedures and/or hepatobiliary surgery safely.

Method: One hundred sixty three Thai subjects were examined by MRCP at KCMH between January 1, 2003 and November 30, 2008. Images of MRCP retrieved were reviewed and classified as type A, conventional pattern; type B, trifurcation; type C, right posterior segmental duct (RP) joining common hepatic duct (CHD); and type D, right posterior segmental duct (RP) joining left hepatic duct (LHD).

Results: The anatomy of the intrahepatic bile ducts was typical (type A) in 65% of cases (n=106). Variations from conventional intrahepatic bile duct anatomy were seen in the remaining 57 patients, showing trifurcation (type B) in 17.2% (n=28), anomalous drainage of RP into CHD (type C) in 5.5% (n=9) and drainage of RP into LHD (type D) in 9.2% (n=15). Other variations in 3.1% (n=5) included the presence of an accessory duct and drainage of RP into common bile duct.

Conclusion: The branching pattern of intrahepatic bile ducts was atypical in 35% of cases. The highest incidence of variation is type B or trifurcation. Our results confirm previous reports. Variant intrahepatic bile duct anatomy is relevant for the practice of safe and efficacious surgical and other hepatobiliary intervention.