Vicarious Excretion of Contrast by the Gallbladder

 

 Hello Glias !!

Vicarious excretion refers to the elimination of contrast media through an alternate organ when the primary pathway (usually kidneys) is impaired or overloaded. When the gallbladder shows opacification after intravenous iodinated contrast, it indicates that the liver and biliary system are partially taking over the role of excreting contrast.

Why does it happen?

Typically seen when:
• Renal function is compromised (AKI, CKD)
• High contrast load is administered
• Delayed imaging after contrast injection
• Hypotension or hemodynamic instability reduces renal clearance

The contrast is taken up by hepatocytes and excreted into bile, causing visible density in:
• Intrahepatic bile ducts
• Common bile duct
• Gallbladder lumen

CT Findings

• Hyperdense bile within gallbladder on delayed or follow-up scans
• Densities can mimic stones or sludge
• No associated wall thickening or obstruction typically

Clinical Importance

• Usually benign and transient
• Clue for reduced renal clearance
• Helpful reminder to check renal function, especially before repeat contrast studies

- Written By Dr. Upasana Y