Acalculous cholecystitis is an acute necroinflammatory disease of the gallbladder associated with underlying diagnoses that lead to gallbladder stasis and ischemia, often resulting in secondary infections with enteric pathogens, including Escherichia coli, Enterococcus faecalis, Klebsiella, Pseudomonas, Proteus species, and Bacteroides. Acalculous cholecystitis accounts for approximately 10% of all cases of acute cholecystitis and is more common in critically ill and hospitalized patients, although it does occur in the outpatient setting.

In critically ill patients, presenting symptoms may include unexplained fever, new leukocytosis, or vague abdominal discomfort. Ambulatory patients may complain of smoldering, typically colicky right upper quadrant (RUQ) pain and positive Murphy sign, but many present with sepsis and peritonitis from gallbladder rupture or necrosis from longstanding acalculous cholecystitis.

Physical examination may reveal a palpable RUQ mass and jaundice, both of which are uncommon in patients with acute calculous cholecystitis. A high index of suspicion for acalculous cholecystitis should be had for patients who have been recently or critically ill with sepsis of an unclear etiology, particularly if vague gastrointestinal complaints are present.