Biliary tree anatomy

Dr Henry Knipe and Dr Omar Bashir et al.

Various channels that collect bile from the hepatic parenchyma and transport it to the duodenum constitute the biliary tree.

Gross anatomy

By convention the biliary tree is divided into intra- and extra-hepatic bile ducts 1. There is significant variation in the biliary tree with the classical description below thought to be present in ~60% of the population 2.

Intrahepatic bile ducts 

Bile canaliculi unite to form segmental bile ducts which drain each liver segment. The segmental ducts then combine to form sectional ducts with the following pattern 5:

  • segments VI and VII: right posterior duct (RPD), coursing more horizontally 
  • segments V and VIII: right anterior duct (RAD), coursing more vertically
  • right posterior and anterior ducts unite to from the right hepatic duct (RHD)
  • segmental bile ducts from II-to-IV unite to form the left hepatic duct (LHD)

The left and right hepatic ducts unite to form the common hepatic duct (CHD). Bile duct(s) from segment I drain into the angle of their union. 

The ducts of the left hepatic lobe are more anterior than those of the right lobe; it is important particularly when contrast cholangiogram is performed because contrast may not opacify nondependent ducts 3

Extrahepatic bile ducts

The common hepatic duct is joined by the cystic duct (from the gallbladder) to form the common bile duct. 

The common bile duct travels initially in the free edge of the lesser omentum, then courses posteriorly to the duodenum and pancreas to unite with the main pancreatic duct to form the ampulla of Vater, which drains at the major duodenal papillae on the medial wall of the D2 segment of the duodenum. 

Variant anatomy

Intrahepatic bile ducts

Variant anatomy is quite common 2:

  • RPD draining into LHD ~15% (range 13-19%)
  • RAD draining into LHD ~6%4
  • RPD draining into anterior (not posterior) aspect of RAD ~12%
  • "triple confluence": union of RPD, RAD and LHD to form CHD ~11%
  • aberrant hepatic duct (typically RPD draining into CHD) ~6%
  • low insertion of right common duct into common hepatic duct ~2%4
  • accessory hepatic ducts ~2%
  • subvesical bile ducts
Extrahepatic bile ducts
Anatomy: Abdominopelvic
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Article information

rID: 18877
Section: Anatomy
Tag: cases
Synonyms or Alternate Spellings:
  • Bile duct

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Cases and figures

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    Case 1: variant "triple confluence" on MRCP
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    Case 2: variant, triple confluence
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