Bile duct dilatation (differential)

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Bile duct dilatation can be due to several etiologies.

Clinical presentation

Variable, depending on underlying cause, but usually:

Radiographic features

Ultrasound

Harmonic imaging is useful when assessing the biliary system, as it improves the clarity of the lumen.

  • intrahepatic bile ducts
    • >2 mm
    • >40% of adjacent portal vein
  • extrahepatic bile ducts (common hepatic duct and common bile duct)
    • usually measured in the proximal duct, near the proper hepatic artery
    • diameter measured from inner wall to inner wall
    • >6 mm +1 mm per decade above 60 years of age
    • >10 mm post-cholecystectomy
  • It is common practice to refer to the common hepatic/bile duct as the common duct (CD) when reporting ultrasound, as the confluence of the cystic duct with the common hepatic duct (CHD) to form the common bile duct (CHD) is often not clearly defined.

Focal dilatation may be a result of downstream stricture, or damage to the elasticity of that segment of bile duct, possibly from prior stone passage.

Color Doppler can be useful to ensure that dilated structures in the liver are actually bile ducts and not an intrahepatic vascular malformation.

Differential diagnosis

The second thing to establish is which part of the biliary system is dilated:

  • intrahepatic
  • extrahepatic
  • intrahepatic and extrahepatic
Intrahepatic biliary dilatation only
Extrahepatic biliary dilatation only
Intrahepatic and extrahepatic biliary dilatation