Teaching Case

Patient with multiple pathology (diabetes mellitus, chronic vasculopathy, obesity, dislipidaemia, COPD, heart failure) and history of widespread weakness, vague lumbar pain, choluria and acholia of recent appearance who was taken to the emergency department with signs of septic shock (fever and hypotesion).

An abdominal ultrasound was performed, disclosing a hydropic gallbladder with thickened walls and bubbles inside, and abundant aerobilia in the left hepatic lobe, suspicious of emphysematous cholecystitis.

In a portal phase abdominal CT, a mural thickening and hypoenhancement affecting the hepatic wall of the gallbladder were shown. No mural emphysema was visible; however, abundant intraluminal gas was seen. A biliar lithiasis was visible in the infundibulum. Aerobilia in the left biliary tree and in the cystic duct was also visible.

A filling defect of the left portal branch was identified, probably indicating secondary thrombophlebitis. Relative hyperperfusion of the left hepatic lobe was suggestive of reactive arterial hyperaemia (transient hepatic attenuation differences - THAD). Additionally, signs suggestive of shock with periportal oedema, splenic hypoperfusion, adrenal hypeperfusion and delayed renal excretion existed.

The findings were suggestive of emphysematous cholecystitis with secondary portal thrombophlebitis and septic shock.

Emphysematous cholecystitis is characterised by inflammation of the gallbladder wall causing necrosis and gas formation. Visualisation of intraluminal or intramural gas are the most specific signs suggesting this form of cholecystitis, computed tomography being the most adequate imaging modality for this finding.

Visualisation of gas in the bile ducts is rare due to cystic duct obstruction. However, emphysematous cholecystitis is commonly not linked to biliary lithiasis (acalculous cholecystitis), occurring secondary to other diseases, mainly vasculopathy (vasculitis, diabetes mellitus…).

Other emerging radiologic signs could be useful in diagnosing emphysematous cholecystitis, for example the ‘pomegranate sign’. This sign has been described in intrathoracic pathologic gas-fluid levels, and consists in a wavy air-fluid interface which resembles a 'pomegranate' in a plane perpendicular to the surface, and is suggestive of fluid infection (exudate) [1].

Correlation with surgical and microbiological findings is essential to determine the usefulness of this finding; in this case, a gangrenous gallbladder was found during the surgery, and cholecystectomy was performed. A dense bile was drained. In the microbiological culture Klebsiella pneumoniae grew, being also positive in blood cultures.

Air visualisation through other imaging modalities (e.g. ultrasound), provides other signs highly specific of this disease. The ‘champagne sign’, in which echogenic foci rising up from the dependent portions of the gallbladder lumen are visible, is one of them.

Emphysematous cholecystitis is an entity in which complications can occur such as secondary portal thrombosis, which is why the radiologist should be aware of it.

Written informed patient consent for publication has been obtained.