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Bile duct serving liver segment V

The bile duct of segment V (according to Couinaud’s classification) is an intrahepatic biliary branch that drains bile from the anterior inferior segment of the right liver lobe. It is one of the segmental ducts that converge into the right hepatic duct.

Segmental ducts are critical in hepatic anatomy as they define surgical planes for liver resection, transplantation, and interventional radiology procedures. The segment V bile duct is particularly relevant in right hepatectomy and living donor liver transplantation.

Synonyms

  • Segment V bile duct

  • Anterior inferior right hepatic duct branch

  • Right anterior inferior duct

Origin, Course, and Drainage

  • Origin: Collects bile from intrahepatic canaliculi of segment V hepatocytes (inferior anterior portion of right lobe)

  • Course: Runs centrally within segment V toward the hepatic hilum

  • Drainage: Joins with the segment VIII duct to form the right anterior sectoral duct, which drains into the right hepatic duct

Relations

  • Anteriorly: Lies beneath the liver capsule of segment V, adjacent to gallbladder fossa

  • Posteriorly: Related to portal vein branches of segment V

  • Superiorly: Close to segment VIII and its bile ducts

  • Inferiorly: Related to gallbladder and cystic duct insertion region

Function

  • Collects bile produced by hepatocytes in segment V

  • Delivers bile through the right anterior sectoral duct into the right hepatic duct

  • Contributes to overall bile flow toward the common hepatic duct and duodenum

Clinical Significance

  • Hepatic surgery: Segmental ducts define resection margins in segmentectomy or right hepatectomy

  • Living donor transplantation: Careful mapping required to preserve and reconstruct segment V duct

  • Biliary obstruction: Stones, strictures, or cholangiocarcinoma may selectively involve segmental ducts

  • Iatrogenic injury: Segment V duct can be injured in cholecystectomy due to proximity to gallbladder fossa

MRI Appearance

T1-weighted images:

  • Duct lumen: dark (low signal)

  • Wall: thin and not normally visualized unless thickened or enhanced

T2-weighted images:

  • Duct lumen: bright (high signal fluid)

  • Wall: thin dark rim

STIR (Short Tau Inversion Recovery):

  • Bile within duct: hyperintense

  • Fat suppressed for better contrast with surrounding parenchyma

T1 Fat-Sat Post-Contrast:

  • Normal ducts: minimal enhancement

  • Pathology (strictures, cholangitis, tumor): wall thickening and enhancement

T2 Fat-Saturated HASTE (single-shot):

  • Segment V duct: very bright tubular structure within right lobe

  • Stones: appear as dark signal voids

  • Excellent for quick screening

T2 TSE Fat-Saturated 3D (MRCP sequence):

  • Duct appears as high-signal linear/tubular structure

  • Enables 3D reconstruction of intrahepatic biliary tree

  • Ideal for preoperative mapping of biliary anatomy

Thick-slab T2 Fat-Saturated HASTE:

  • Shows segment V duct as part of the bright biliary tree projection

  • Useful for overview of intrahepatic ducts in one thick slice

CT Appearance

Non-Contrast CT:

  • Ducts are usually not visible unless dilated

  • Dilated segment V duct: appears as low-attenuation tubular structure in right lobe

Post-Contrast CT:

  • Duct wall may show subtle enhancement

  • Biliary obstruction: duct dilation visible as branching low-density tubular structures

  • Pathology: cholangiocarcinoma appears as enhancing soft tissue narrowing the duct lumen

MRI image

Bile duct serving liver segment V MRI axial anatomy image-img-00000-00000