Bile duct

At a glance

English

Bile duct

Latin (TA2)

Ductus biliaris

System

Digestive

Region

Abdomen

Side

Single, on the midline

About the bile duct

Bile made by the liver leaves through the right and left hepatic ducts, which join near the porta hepatis to form the common hepatic duct. A short distance lower, the cystic duct from the gallbladder joins it, and from that point on the channel is the bile duct, often still called the common bile duct. It is about 7 to 8 cm long and normally a few millimetres wide, and it carries bile both directly from the liver and, after a meal, from the gallbladder store.

Its course is described in parts. The upper, supraduodenal part runs down in the free right edge of the lesser omentum (the hepatoduodenal ligament), with the hepatic artery proper on its left and the portal vein behind, forming the front wall of the opening into the lesser sac. It then passes behind the first part of the duodenum, and next lies in a groove on, or tunnelled through, the back of the head of the pancreas. Finally it enters the inner wall of the descending duodenum, where it usually meets the pancreatic duct and opens through the hepatopancreatic ampulla on the major duodenal papilla.

Bile is an alkaline fluid of water, bile salts, cholesterol, phospholipid and the pigment bilirubin. The salts break fat into small droplets so that pancreatic lipase can work on it, and they are later reabsorbed from the ileum and returned to the liver. Smooth-muscle sphincters around the end of the duct close between meals, so bile backs up into the gallbladder, where it is concentrated.

Gallstones that slip out of the gallbladder can lodge in the duct, a condition called choledocholithiasis. The blockage stops bile reaching the bowel, giving jaundice, dark urine and pale stools, and can lead to ascending infection of the ducts (cholangitis) or, at the ampulla, to pancreatitis. A tumour in the head of the pancreas can compress the lower duct and cause painless jaundice. The surgeon's view of the duct in the hepatoduodenal ligament is critical during gallbladder removal, when it must not be mistaken for the cystic duct.

Function and supply

Begins at

Formed by the union of the common hepatic duct and the cystic duct, usually just below the porta hepatis in the hepatoduodenal ligament.

Ends at

Ends in the wall of the descending duodenum, usually joining the pancreatic duct at the hepatopancreatic ampulla on the major duodenal papilla.

Function

Carries bile from the liver and gallbladder to the duodenum, where bile salts emulsify dietary fat.

Nerve supply

Autonomic fibres from the hepatic plexus, with sympathetic and vagal components; pain from distension travels with sympathetic fibres to the upper abdomen.

Blood supply

Supplied by small vessels running along its length from the cystic, right hepatic and gastroduodenal arteries, including the posterior superior pancreaticoduodenal artery.