Acute acalculous cholecystitis

Acute acalculous cholecystitis refers to the development of cholecystitis in a gallbladder either without gallstones or with gallstones where they are not the contributory factor. It is thought to occur most often due to biliary stasis and/or gallbladder ischemiaischaemia.

Epidemiology

Acute acalculous cholecystitis represents 5-10% of cases of acute cholecystitis.

Pathology

Acute acalculous cholecystitis usually occurs in critically ill or injured patients (e.g.  trauma, burns, sepsis). IschemiaIschaemia/reperfusion injury to the gallbladder is a central pathogenic feature. Other contributory factors include ⁹:

• bile stasis, e.g. from various causes of cystic duct obstruction
• opioid therapy
• positive-pressure ventilation (PPV)
• total parenteral nutrition (TPN)
• cocaine-related (rare)
• advanced age and cerebrovascular accidents ¹²
• major surgery (e.g. heart valves), trauma, and burns ¹³

A rare cause of acalculous cholecystitis occurring in patients with advanced cancer is gallbladder metastases ¹⁰.

Radiographic features

When there are no gallstones, the diagnosis is more obvious.

Ultrasound

May show gallbladder wall edemaoedema, pericholecystic fluid, and gallbladder distention (the first two considered the two most important criteria ²). The sonographic Murphy's sign may be positive. A sonolucent intramural layer or “halo” that represents intramural edemaoedema may also be present.

A sonogram may be considered highly suggestive of the diagnosis with two of the following major criteria, or one major and two minor criteria fulfilled ¹⁴;

• major criteria
  • gallbladder wall thickness > 3 mm
  • wall striation
  • pericholecystic fluid
  • sonographic murphy's sign
  • intramural gas
  • mucosal sloughing
• minor criteria
  • echogenic bile or sluge in lumen
  • transverse diameter greater than 5 cm

Scintigraphy

Tc-99m iminodiacetic acid cholescintigraphy is considered a highly reliable test and may be performed even in acutely ill patients. Ideally, there is non-visualization-visualisation of the gallbladder.

Treatment and prognosis

The importance of recognizing acalculous cholecystitis lies in the fact that these patients have a high rate of recurrence when treated with medical management. As such, cholecystectomy is the definitive treatment. However, patients that are not fit for surgery can undergo percutaneous or endoscopic biliary drainage as alternative therapy, though cholecystectomy may still be performed when the patient improves.