Common bile duct

The common bile duct (CBD), which is sometimes simply known as the bile duct, is formed by the union of the cystic duct and common hepatic duct (CHD)

On ultrasound imaging, it is not always possible to confidently see where the cystic duct enters the common hepatic duct to form the common bile duct. Therefore it is common practice to use the term common duct (CD) as a term conflating the common hepatic and common bile ducts. 

The CBD is approximately 8 cm long and usually <6 mm wide in internal diameter but this can be dependent on a number of factors including age and prior cholecystectomy. It joins the pancreatic duct at the ampulla of Vater, which drains into the second part of the duodenum through the major duodenal papilla.

The common bile duct is supplied by a network of arteries from several sources:

There are four main relationships of the CBD with the pancreatic head 2:

  • partially covered posteriorly (most common: ~50%)
  • completely covered
  • completely uncovered
  • CBD may pass laterally to the pancreatic head (least common)
Anatomy: Abdominopelvic
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Article information

rID: 24814
Section: Anatomy
Synonyms or Alternate Spellings:
  • Common duct (ultrasound)
  • CBDs
  • Common bile ducts
  • CBD
  • Common bile duct (CBD)

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Cases and figures

  • Figure 1
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  • Figure 2: common duct anatomy and variation
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  • Case 1: normal CT intravenous cholangiogram
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  • Case 2 : normal MRCP
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  • Case 3: obstructing stones in common bile duct
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