Gas-containing gallstones as a cause of the 'effervescent gallbladder' sign and pneumobilia

The "effervescent gallbladder" sign, the sonographic finding of tiny echogenic foci rising from the dependent portion of the gallbladder, reminiscent of bubbles rising in a glass of champagne, has been reported previously as a finding of emphysematous cholecystitis. We report two additional cases of this unusual finding in an asymptomatic patient and in a patient with acute, gangrenous cholecystitis, confirmed in both cases by CT, to be secondary to the release of gas from gallstones. These two cases cast doubt on the sonographic sign as a pathognomonic finding of emphysematous cholecystitis.