The air-filled left hepatic duct: the saber sign as an aid to the radiographic diagnosis of pneumobilia.

Abstract

In the supine patient, gas rises to the left hepatic duct. Radiographically, this can be recognized as a saber-shaped lucency to the right of the spine. In a retrospective analysis and review of the radiographs of 40 patients shown to have gas in the biliary tree by ultrasound (US), computed tomography (CT), or radiography, the diagnosis could be made in 37 patients. In 18 of these 37 cases pneumobilia could be identified by the saber-shaped distribution of gas. Knowledge of the medial distribution of biliary gas in the supine patient and appreciation of the saber sign can increase the sensitivity of the radiographic detection of pneumobilia.