IS Case 410: Variant biliary drainage

Gunvir Gill, MD

University of Rochester

Imaging Sciences URMC 2010
Publication Date: 2010-08-27


Patient is a 49-year-old woman post-cholecystectomy for acute cholecystitis. Patient subsequently had liver function test abnormalities. An endoscopic retrograde cholangiopancreatography (ERCP) was performed to evaluate for obstruction.


Two fluoroscopic views obtained during an ERCP show right posterior segment duct draining into the left hepatic duct and then into the common hepatic duct (CHD). Patient is post-cholecystectomy with surgical clips adjacent to the cystic duct remnant.


Variant biliary drainage


Familiarity with segmental hepatic biliary anatomy is essential for both staging and localization of intrahepatic liver neoplasms or bile duct tumors. Furthermore, evaluation of the biliary anatomy is essential before hepatic lobectomy or segmentectomy. Inaccurate determination of existing biliary anatomic variations may potentiate ligature or section of these aberrant ducts, leading to major complications. Magnetic resonance cholangiopancreatography (MRCP) or ERCP allows delineation of a patient's biliary anatomy.

The right posterior duct usually runs posterior to the right anterior duct and fuses it from a left (medial) approach to form the right hepatic duct. The common hepatic duct is formed by fusion of the right hepatic duct, which is usually short, and the left hepatic duct. The cystic duct classically joins the common hepatic duct below the confluence of the right and left hepatic ducts. This most common biliary anatomy is thought to be present in 58% of the population.

In general, anatomic variants in the branching of the biliary tree involve the right posterior duct and its fusion with the right anterior or left hepatic duct. Of these, drainage of the right posterior duct into the left hepatic duct before its confluence with the right anterior duct is the most common anatomic variant of the biliary system and reported to occur in 13-19% of the population.


  1. Mortelé KJ, Ros PR. Anatomic variants of the biliary tree: MR cholangiographic findings and clinical applications. AJR Am J Roentgenol. 2001 Aug;177(2):389-94. PMID: 11461869

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