Emphysematous cholecystitis is a severe complication of acute cholecystitis caused by a gas forming bacteria such as Clostridium perfringens, Escherichia coli, and Bacillus fragilis.

Gas may be present either within the lumen or the wall of the gallbladder. It is more common in patients with diabetes and carries a greater risk of perforation. Acute gallbladder perforation has a very high mortality due to generalized bile peritonitis.