Air in the biliary tree in the plain abdominal radiograph

Causes of air in the biliary tree include:

• ERCP +/- sphincterotomy
• gas producing infections - emphysematous cholangitis
• trauma
• gallstone perforation
• recent passage of a stone
• sclerosing cholangitis } processes that hold the
• cirrhosis with scarring } biliary tree open
• tumour - cholangiocarcinoma }