Gangrenous cholecystitis

Gangrenous cholecystitis (GC) is an ominous progression of acute cholecystitis in which infection, inflammation, edema, bile stasis and ischemia lead to gallbladder necrosis and perforation. Risk factors reported in the literature for GC include male gender, older age, diabetes, concurrent chronic illness, leukocytosis and prominent peritoneal signs. Mortality in GC ranges from 15-40%, much higher than in acute Cholecystitis.

Clinical presentation may not be straightforward, since many patients will have diffuse abdominal pain and peritoneal signs, rather than classical right upper quadrant pain, however these patients are usually in patients and very sick.

If the clinical diagnosis is cholecystitis, initial imaging is usually ultrasound. Sonographic signs of acute non-gangrenous Cholecystitis include intraluminal stones, impacted stone in the neck of gallbladder and gallbladder tenderness (sonographic Murphy’s sign). Gallbladder distension, wall thickening are non-specific. In GC there are occasionally observed hyperechoic linear structures within the lumen representing membranes of desquamated gallbladder lining. There are often pericholecystic fluid collections representing perforation and possible abscess formation. In addition, the gallbladder wall thickening is often very marked and there may be a striated appearance to the wall, or irregular protrusions within the lumen. The sonographic Murphy’s sign may be paradoxically absent, presumably because of necrosis and denervation of the gallbladder; its absence in a patient otherwise highly suspicious for acute cholecystitis raises the suspicion for GC. Rarely, there may be evidence of intraluminal or intramural air, although this finding is not pathognomonic for GC. Emphysematous cholecystitis may exist without gangrene of the gallbladder in infection with gas-forming organisms. In addition, if a patient has undergone recent percutaneous cholecystostomy, there may be residual gas in the gallbladder. Similarly, if there is a fistula between the gallbladder and bowel, as occurs in gallstone ileus, there may be gas in the gallbladder.

CT is quite accurate in the diagnosis of acute cholecystitis, with the most common findings including gallstones, gallbladder distension and wall thickening, and pericholecystic inflammation. Sensitivity for progression to GC is not high, since most findings overlap. However, certain findings greatly increase specificity: the presence of intraluminal membranes, irregular or absent gallbladder wall, abscess, and the rare presence of intraluminal or intramural gas. The presence of pericholecystic fluid supports the diagnosis. Occasionally, the gallbladder will be seen not to enhance after intravenous contrast administration. In addition, the degree of short axis gallbladder distension is more marked in GC.

GC is an emergency, and urgent cholecystectomy is generally performed in an attempt to reduce morbidity and mortality. However, in a patient at very high risk for general anesthesia, the interventional radiologist may have to perform percutaneous cholecystostomy as a temporizing measure prior to definitive treatment.