Common bile duct compression by an abdominal aortic aneurysm: an unusual cause of biliary tract dilatation.

Extra-hepatic bile duct compression is encountered commonly among patients with pancreatic disease, primary sclerosing cholangitis, and cholangiocarcinoma. However, in an elderly lady with predominantly cholestatic liver test abnormalities, magnetic resonance cholangiopancreatography (MRCP) demonstrated a large abdominal aortic aneurysm that was causing extra-hepatic bile duct compression and concomitant proximal bile duct dilatation. This unusual and uncommon finding was almost certainly the explanation for her liver test dysfunction. This report draws attention to the increasing role for MRCP as an accurate, but non-invasive means of appraisal of the pancreatico-biliary tree. In addition, an unusual and uncommon cause of extra-hepatic bile duct compression is discussed.