Skip to content

Biliary obstruction

Intrahepatic ducts

Normal:
- Often seen as parallel channels adjacent to portal veins
- Should not be >40% diameter of adjacent portal vein
- Should not be >2mm in diameter

  • Can differentiate dilated intrahepatic ducts from portal veins by:
    • Tortuosity or wall irregularity
    • Presence of increased through transmission
    • Stellate configuration centrally
  • May see "parallel channel sign" where there are two parallel channels and assume one represents portal vein and the other is a dilated intrahepatic duct
    • Important to doppler as one of the channels may actually be a hepatic artery that is dilated as a result of portal hypertension where there is increase hepatic arterial flow to compensate for decreased portal venous flow

Extrahepatic ducts

Choledocholithiasis
  • Most stones are in the distal-most portion of the intrapancreatic duct near the ampulla of Vater
  • Much lower sensitivity for detecting ductal stones compared to gallbladder stones (has been reported as ~75%)
    • Even if no stone is seen most of these patients will have dilated ducts
  • Pitfall: cystic duct insertion may look like a stone in some cases