Biliary Tree

Overview

Series of coalescing ducts conducting bile from the hepatic parenchyma to the duodenum with some bile stored in the gallbladder when quiescent. The organisation of the biliary system follows that of the portal system and segmentation of the liver.

Segments

Intrahepatic Ducts and Hepatic Ducts

• Bile canaliculi unite to form segmental bile ducts which drain each liver segment
• Segmental bile ducts of segments VI and VII combine to form right posterior duct, coursing horizontally
• Segmental bile ducts of segments V and VIII combine to form right anterior duct, coursing more vertically
• The right posterior and anterior ducts unite to form right hepatic duct
• Segmental bile ducts of segments II, III and IV unite to form left hepatic duct
• The left and right hepatic ducts unite to form common hepatic duct
• Segment I is drained by several ducts joining both the right and left ducts close to the biliary confluence at the hilum (or may join left hepatic duct)

Cystic Duct

• Arises from neck of gallbladder
• Courses posteroinferiorly to join the common hepatic duct
• In front of right hepatic artery and its cystic branch

Common Bile Duct

Leaves the liver through invagination of Glisson’s capsule at the hilum. Travels within free border of hepatoduodenal ligament with the portal triad (bile duct on the right, hepatic artery on the left, and portal vein posteriorly and in between). There are three parts:

• Supraduodenal – lies in free edge of lesser omentum and with the portal triad
• Retroduodenal – Posterior to 1st part of duodenum
  • Slopes right (portal vein is now on its left with GDA)
  • IVC is a posterior relationship
• Paraduodenal – grooves back of head of pancreas and crosses anterior to right renal
  vein
  • Joins pancreatic duct at ampulla of vater (surrounded by sphincter of oddi)
  • Drains into major duodenal papilla

Arterial Supply

The arteries of the supraduodenal bile duct arise from the:

• Retroduodenal artery
• Gastroduodenal artery
• Right branch of the hepatic artery
• Cystic artery

Venous Drainage

The veins draining the bile duct usually exist parallel to corresponding arteries along the border of the common bile duct.

Lymphatic Drainage

Two usual pathways:

• Superiorly with lymph nodes along the cystic duct, hepatic artery, and celiac axis
• Inferiorly with lymph nodes along the cystic duct, the anterolateral aspect of the portal vein, the posterior pancreas, and between the aorta and inferior vena cava.

Anatomical Variants

Large variations in intrahepatic draining patterns exists:

• Right posterior duct draining into left hepatic duct
• Right anterior duct draining into left hepatic duct
• Right posterior duct draining into anterior aspect of right anterior duct
• Triple confluence – union of right posterior duct, right anterior duct and left hepatic duct to form common hepatic duct
• Aberrant hepatic duct (typically right posterior duct draining into common hepatic duct)
• Low insertion of RHD into CHD
• Accessory hepatic ducts
• Subvesical bile ducts