• May occur due to sphincterotomy, or Roux loop procedure.
  • Reflux of gas from intestinal tract into biliary tree
  • Linear distribution radiating from hilum 
  • Air predominantly in non-dependent portions of biliary tree
  • US: echo-reflective linear structures. Distinguished from calcification by their movement with respiration, bowel peristalsis or patient position. 
  • CT: extremely sensitive, easily visualized. 
Read more

Shah, Priti A., et al. “Hepatic gas: widening spectrum of causes detected at CT and US in the interventional era.” Radiographics 31.5 (2011): 1403-1413.

Sherman, Scott C., and Huy Tran. “Pneumobilia: benign or life-threatening.” The Journal of emergency medicine 30.2 (2006): 147-153.