The ultrasound appearance of acute calculous cholecystitis has been discussed in a previously published case [click here to view]

This case has been illustrated here to demonstrate one of the complications of acute cholecystitis - empyema of the gallbladder. Bacterial infection of the bile in the obstructed gallbladder typically results in empyema, a distended gallbladder filled with pus and debris.  If untreated, pyogenic cholecystitis may lead to generalized sepsis and/or gangrene/perforation of the gallbladder.

In a typical case of cholecystitis complicated by empyema, along with the usual ultrasound findings of cholecystitis, a distended gallbladder filled with fluid that shows multiple echoes and debris will be seen.

Sometimes in cases of calculous cholecystitis, calculi fill the lumen to such a great extent [as in this case] that it is not possible to assess the echogenicity of the bile, the hallmark of empyema. In this case, ultrasound alone is of limited use to diagnose pus within the gallbladder. Combined ultrasound, clinical and laboratory criteria may help arrive at the correct final diagnosis.