“Pneumobilia should be differentiated from portal venous gas. Portal venous gas is peripherally distributed to within 2 cm of the liver margin, whereas pneumobilia is centrally distributed.” (Gupta, P, et al. “PLAIN FILMS: BASICS.” Acute Care Surgery: Imaging Essentials for Rapid Diagnosis Eds. Kathryn L. Butler, et al. McGraw Hill, 2015.)