Complications of cholecystitis and their appearance on Ultrasound
Complications of cholecystitis include gallbladder gangrene, hemorrhage, perforation, and emphysema. Gangrenous cholecystitis is diagnosed on US by visualizing nonlayering bands of echogenic tissue in the lumen due to sloughed membranes and blood. The gallbladder wall also becomes more irregular with small wall collections due to abscesses or hemorrhage. The sonographic Murphy’s sign is also usually absent with gangrene. Hemorrhagic cholecystitis is also a gangrenous process wherein there is bleeding into the gallbladder wall and lumen with resultant low-level echoes to heterogeneous echoes filling the gallbladder lumen. Gallbladder perforation may be directly detected as a focal defect in the gallbladder wall or via secondary signs of gallbladder collapse and pericholecystic fluid collection. Emphysematous cholecystitis is a rare but potentially fatal condition, which is more commonly seen in diabetics and may occur in the absence of gallstones. Gas in the gallbladder wall and lumen appears as echogenic lines with dirty posterior acoustic shadowing.