Common bile duct
Ductus choledochus (ductus biliaris)
Also known as: bile duct, CBD, choledochus
The common bile duct is formed by the union of the cystic and common hepatic ducts. It runs about 6–8 cm behind the duodenum and through the head of the pancreas, then joins the pancreatic duct to open at the major duodenal papilla.
Overview
The bile duct is normally up to about 6 mm in diameter; it is often slightly wider in older people and after cholecystectomy. It has four parts. The supraduodenal part lies in the free edge of the lesser omentum, in front of the portal vein and to the right of the hepatic artery proper, and forms the anterior boundary of the omental foramen. The retroduodenal part passes behind the 1st part of the duodenum, to the right of the gastroduodenal artery. The pancreatic part runs in a groove or tunnel in the back of the pancreatic head, in front of the IVC. The intraduodenal part passes obliquely through the wall of the 2nd part of the duodenum to join the main pancreatic duct at the hepatopancreatic ampulla.
Around its terminal part, the sphincter of the bile duct (part of the sphincter of Oddi complex) controls flow. Its tone between meals diverts bile into the gallbladder.
The supraduodenal duct is supplied by small axial arteries running at 3 and 9 o'clock, fed from the retroduodenal and right hepatic arteries. Stripping or diathermy near the duct can devascularise it and cause an ischaemic stricture.
- Location
From the junction of the cystic and common hepatic ducts (in the hepatoduodenal ligament) to the major duodenal papilla.
Parts & subdivisions
- In the free edge of the lesser omentum; the anterior boundary of the omental foramen.
- Behind the first part of the duodenum, near the gastroduodenal artery.
- Groove or tunnel in the posterior pancreatic head; compressed by pancreatic head tumours.
- Oblique course through the duodenal wall to the ampulla.
Anatomy
- Arterial supply
Small branches of the cystic, right hepatic, gastroduodenal and posterior superior pancreaticoduodenal (retroduodenal) arteries, forming the 3 o'clock and 9 o'clock axial vessels.
- Lymphatic drainage
Hepatic and pancreaticoduodenal nodes.
- Relations
Supraduodenal: hepatic artery proper (left), portal vein (posterior). Retroduodenal: gastroduodenal artery (left), IVC (behind). Pancreatic: embedded in the head, IVC behind.
Function
- Carries bile from the liver and gallbladder to the duodenum.
Clinical significance
Choledocholithiasis and cholangitis
Stones in the bile duct cause obstructive (conjugated) jaundice with pale stools, dark urine, pruritus and raised ALP and GGT. Infection above an obstruction causes ascending cholangitis. Its signs are the Charcot triad (fever, jaundice, right upper quadrant pain) or the Reynolds pentad (adding hypotension and confusion). It is an emergency needing antibiotics and ERCP drainage.
Pancreatic head carcinoma
Compresses the pancreatic part of the duct and causes painless progressive jaundice, often with a palpable gallbladder (Courvoisier). Imaging shows the "double-duct sign" (dilated bile and pancreatic ducts).
Biliary atresia
Progressive fibrosing obliteration of the extrahepatic ducts in infancy. It presents with persistent conjugated jaundice beyond 2 weeks of age and pale stools. Kasai portoenterostomy should be done early, ideally before about 60 days. It is the commonest indication for paediatric liver transplantation.
Compiled from standard anatomy and physiology references — see the Digestive System sources. For education only; not medical advice.