View source for Biology:Common bile duct

{{Short description|Gastrointestinal duct}}
{{Infobox anatomy
| Name        = Common bile duct
|acronym      = CBD<ref name="AgabegiAgabegi2012">{{cite book|last1=Agabegi|first1=Steven S.|last2=Agabegi|first2=Elizabeth D.|title=Step-Up to Medicine|date=23 August 2012|publisher=Lippincott Williams & Wilkins|language=en |isbn=9781609133603|page=136}}<!--|access-date=10 June 2015--></ref>
| Latin       = ductus choledochus,<ref name=":0" /><br />ductus biliaris<ref name=":0" />
| Image       = Diagram showing the position of the perihilar bile ducts CRUK 357.svg
| Caption     = Diagram of the biliary tree showing the common bile duct
| System      =
| part_of = [[Medicine:Biliary tract|Biliary tract]]
}}
The '''bile duct'''<ref name=":0">{{Cite web |title=Anatonomina |url=http://terminologia-anatomica.org/en/Terms/Occurence/2767 |access-date=2023-07-07 |website=terminologia-anatomica.org}}</ref><ref name=":022" /> (formerly known as the '''common bile duct'''<ref name=":022">{{Cite book |last=Sinnatamby |first=Chummy S. |title=Last's Anatomy |vauthors= |publisher= |year=2011 |isbn=978-0-7295-3752-0 |edition=12th |pages=263–266}}</ref>) is a part of the [[Medicine:Biliary tract|biliary tract]].<ref name=":022" /> It is formed by the union of the [[Biology:Common hepatic duct|common hepatic duct]] and [[Biology:Cystic duct|cystic duct]]. It ends by uniting with the pancreatic duct to form the hepatopancreatic ampulla. It possesses its own [[Biology:Sphincter|sphincter]] to enable regulation of bile flow.

== Anatomy ==
The bile duct is some 6–8&nbsp;cm long, and normally up to 8&nbsp;mm in diameter.<ref name=":022" />

Its proximal supraduodenal part is situated within the free edge of the lesser omentum. Its middle retroduodenal part is oriented inferiorly and right-ward, and is situated posterior to the first part of the duodenum, and anterior to the inferior vena cava. Its distal paraduodenal part is oriented still more right-ward, is accommodated by a groove upon (sometimes a channel within) the posterior aspect of the head of the pancreas, and is situated anterior to the right renal vein.<ref name=":022" />

The bile duct terminates by uniting with the pancreatic duct (at an angle of about 60°) to form the hepatopancreatic ampulla.<ref name=":022" />

The distal extremity of the bile duct invariably features its own [[Biology:Sphincter|sphincteric muscle]] (the pancreatic duct and the hepatopancreatic ampulla usually possess sphincters of their own to allow the flow of pancreatic juice to be regulated independently, however, these two can be absent).<ref name=":022" />

==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 <ref>{{Cite web|last=Oh|first=Lawrence|title=Common bile duct {{!}} Radiology Reference Article {{!}} Radiopaedia.org|url=https://radiopaedia.org/articles/common-bile-duct|access-date=2021-08-30|website=Radiopaedia|language=en-US}}</ref> with a further 1mm diameter allowed for each decade over 60 years.

It normally gets slightly dilated after [[Medicine:Cholecystectomy|cholecystectomy]], with upper limit (95% [[Prediction interval|prediction interval]]) being about 10&nbsp;mm after a few months.<ref name="FengSong1995">{{cite journal|last1=Feng|first1=B|last2=Song|first2=Q|title=Does the common bile duct dilate after cholecystectomy? Sonographic evaluation in 234 patients.|journal=American Journal of Roentgenology|volume=165|issue=4|year=1995|pages=859–861|issn=0361-803X|doi=10.2214/ajr.165.4.7676981|pmid=7676981}}</ref>

On [[Medicine:Abdominal ultrasonography|abdominal ultrasonography]], the common bile duct is most readily seen in the porta hepatis (where the CBD lies anterior to the portal vein and hepatic artery). The absence of [[Medicine:Doppler ultrasonography|Doppler]] signal distinguishes it from the portal vein and hepatic artery.

<gallery>
File:Ultrasonography of common hepatic duct, labeled.jpg|Borderline of a dilated perihilar bile duct, measuring 8&nbsp;mm.
File:Ultrasound Scan ND 090551 0930550 cr.png|Dilatation of CBD due to Ampullary tumor.
</gallery>

=== Obstruction ===
Tumours in the head of the pancreas [[Medicine:Mass effect|may come to]] obstruct the distal bile duct.<ref name=":022" />

If obstructed by a [[Medicine:Gallstone|gallstone]], a condition called choledocholithiasis can result.<ref>{{cite book|last1=Humes|first1=H. David|title=Kelley's Essentials of Internal Medicine|date=2001|publisher=Lippincott Williams & Wilkins|isbn=978-0781719377|page=229|url=https://books.google.com/books?id=ejEQBW9P8uUC&q=choledocholithiasis+gall+stone}}</ref> In this obstructed state, the duct is especially vulnerable to an infection called [[Medicine:Ascending cholangitis|ascending cholangitis]]. One form of treatment is a [[Medicine:Cholecystenterostomy|cholecystenterostomy]]. Rare deformities of the common bile duct are cystic dilations (4&nbsp;cm), choledochoceles (cystic dilation of the ampula of Vater (3–8&nbsp;cm)), and [[Medicine:Biliary atresia|biliary atresia]].

==History==
Obstruction of the common bile duct and related [[Medicine:Jaundice|jaundice]] has been documented since at least since the time of Erasistratus.<ref>{{cite book|editor-last1=Bateson|editor-first1=Malcolm C.|title=Gallstone Disease and its Management|date=1986|publisher=Springer Netherlands|location=Dordrecht|isbn=9400941730|page=Epidemiology (chapter)}}</ref>

==Additional images==
<gallery>
File:Gray1095-gall_bladder.png|The gall-bladder and bile ducts laid open.

</gallery>

== See also ==
* Choledochoduodenostomy - a surgical procedure to create a connection between the common bile duct (CBD) and an alternative portion of the duodenum.

== References ==
{{Reflist}}
* {{cite journal |last1=Miederer |first1=S. |last2=Lindstaedt |first2=H. |last3=Siedek |first3=M. |last4=Franken |first4=Th. |title=Endoskopische transpapilläre Spaltung einer Choledochocele |journal=Deutsche Medizinische Wochenschrift |date=1978 |volume=103 |issue=5 |pages=216–219 |doi=10.1055/s-0028-1104409 |trans-title=Endoscopic transpapillary Splitting of a choledochocele |language=de|pmid=631041}}

==External links==
* {{SUNYAnatomyFigs|38|06|08}}—"The gallbladder and extrahepatic bile ducts."
* {{SUNYAnatomyImage|8|3|36}}
* {{SUNYAnatomyImage|7|9|57}}
* {{NormanAnatomy|Liver}} ({{NormanAnatomyFig|biliarysystem}})


{{DEFAULTSORT:Common Bile Duct}}
[[Category:Digestive system]]
[[Category:Hepatology]]

{{Sourceattribution|Common bile duct}}