Biliary Gas – Xray, Ultrasound and CT Scan Examination

Clinical Characteristics of Biliary Gas

Gas within the biliary tree is often an incidental finding secondary to medical intervention, such as a sphincterotomy or cholecystoenterostomy.

Other cause include:

• A lax sphincter of oddi in the elderly.
• Passage of a gallstone
• Bialiary fistulae caused by stones, neoplasia or duodenal ulceration.
• Biliary gas may result in gas within gallbladder.
• Gas within the gallbladder may be secondary to emphysematous cholecystitis. This is an infection with gas forming organisms, seen in diabetics and leading to mural and intraluminal gallbladder gas.

Radiological Examinations - Biliary Gas

Xray Examination

A branching radiolucencies are seen within the liver. These radiolucencies do not extend to the liver edge: a feature that helps to differentiate biliary gas from gas in the portal vien. Gas in the gallbladder may result in a gas-fluid level on an erect radiographic film.

Ultasound Examination – Biliary Gad

Linear echogenic shadows, paralleling the portal venous system, are the characteristic appearance of biliary gas. Biliary calculi in ultrasound may be identified.

Air in the biliary tree seen as linear echogenic shadow
paralleling the portal venous system ( arrowhead).

Computed Tomography Examination

Branching air densities that parallel the portal system will be seen. Calculi, fistulae or neoplastic masses may be identified.

Air in the biliary tree. CT scan elegantly demonstrates the air (arrows).
The relationship to the portal venous system is clear.