The common bile duct, sometimes abbreviated as CBD, is a duct in the gastrointestinal tract of organisms that have a

gallbladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath the liver, although ...

. It is formed by the confluence of the

common hepatic duct The common hepatic duct is the first part of the biliary tract. It joins the cystic duct coming from the gallbladder to form the common bile duct. Structure The common hepatic duct is the first part of the biliary tract. It is formed by the c ...

and

cystic duct The cystic duct is the short duct that joins the gallbladder to the common hepatic duct. It usually lies next to the cystic artery. It is of variable length. It contains ' spiral valves of Heister', which do not provide much resistance to the ...

and terminates by uniting with

pancreatic duct The pancreatic duct, or duct of Wirsung (also, the major pancreatic duct due to the existence of an accessory pancreatic duct), is a duct joining the pancreas to the common bile duct. This supplies it with pancreatic juice from the exocrine pancr ...

, forming the ampulla of Vater. The flow of bile from the ampulla of Vater into the duodenum is under the control of the

sphincter of Oddi The sphincter of Oddi (also hepatopancreatic sphincter or Glisson's sphincter), abbreviated as SO, is a muscular valve that in some animals, including humans, controls the flow of digestive juices (bile and pancreatic juice) out of the pancreas ...

. When the sphincter of Oddi is closed, newly synthesized bile from the liver is forced into storage in the gallbladder. When open, the stored and concentrated bile (now mixed with pancreatic secretions) exits into the duodenum and takes part in

digestion Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intest ...

. This conduction of bile is the main function of the common bile duct. The hormone

cholecystokinin Cholecystokinin (CCK or CCK-PZ; from Greek ''chole'', "bile"; ''cysto'', "sac"; ''kinin'', "move"; hence, ''move the bile-sac (gallbladder)'') is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat an ...

, when stimulated by a fatty meal, promotes bile secretion by increased production of hepatic bile, contraction of the gallbladder, and relaxation of the sphincter of Oddi.

Clinical significance

Several problems can arise within the common bile duct, usually related to its obstruction. Opinions vary slightly on the maximum calibre of a normal CBD, but 6mm is one accepted upper limit of normal with a further 1mm diameter allowed for each decade over 60 years. It normally gets slightly dilated after cholecystectomy, with upper limit (95%

prediction interval In statistical inference, specifically predictive inference, a prediction interval is an estimate of an interval in which a future observation will fall, with a certain probability, given what has already been observed. Prediction intervals are ...

) being about 10 mm after a few months. On

abdominal ultrasonography Abdominal ultrasonography (also called abdominal ultrasound imaging or abdominal sonography) is a form of medical ultrasonography (medical application of ultrasound technology) to visualise abdominal anatomical structures. It uses transmission a ...

, the common bile duct is most readily seen in the

porta hepatis The porta hepatis or transverse fissure of the liver is a short but deep fissure, about 5 cm long, extending transversely beneath the left portion of the right lobe of the liver, nearer its posterior surface than its anterior border. It join ...

(where the CBD lies anterior to the portal vein and

hepatic artery The common hepatic artery is a short blood vessel that supplies oxygenated blood to the liver, pylorus of the stomach, duodenum, pancreas, and gallbladder. It arises from the celiac artery and has the following branches: Additional images ...

). The absence of Doppler signal distinguishes it from the portal vein and

. File:Ultrasonography of common hepatic duct, labeled.jpg, Borderline of a dilated perihilar bile duct, measuring 8 mm. File:Ultrasound Scan ND 090551 0930550 cr.png, Dilatation of CBD due to Ampullary tumor. If obstructed by a

gallstone A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of mi ...

, a condition called

choledocholithiasis Common bile duct stone, also known as choledocholithiasis, is the presence of gallstones in the common bile duct (CBD) (thus '' choledocho-'' + ''lithiasis''). This condition can cause jaundice and liver cell damage. Treatments include choledocholi ...

can result. In this obstructed state, the duct is especially vulnerable to an infection called ascending cholangitis. One form of treatment is a

cholecystenterostomy A cholecystoenterostomy is a surgical procedure in which the gall bladder is joined to the small intestine. It is performed in order to allow bile to pass from the liver to the intestine when the common bile duct The common bile duct, sometim ...

. Rare deformities of the common bile duct are cystic dilations (4 cm), choledochoceles (cystic dilation of the ampula of Vater (3–8 cm)), and biliary atresia.

History

Obstruction of the common bile duct and related jaundice has been documented since at least since the time of

Erasistratus Erasistratus (; grc-gre, Ἐρασίστρατος; c. 304 – c. 250 BC) was a Greek anatomist and royal physician under Seleucus I Nicator of Syria. Along with fellow physician Herophilus, he founded a school of anatomy in Alexandria, where th ...

Additional images

File:Gray1095-gall_bladder.png, The gall-bladder and bile ducts laid open.

References

External links

* - "The gallbladder and extrahepatic bile ducts." * * * () {{DEFAULTSORT:Common Bile Duct Digestive system Hepatology Gallbladder

Clinical significance

History

Additional images

See also

References

External links