Applied Radiology

Prepared by Hernan A. Bazan, MD , Rogelio Torrecampo, MD , and Unsup Kim, MD , from the Department of Surgery, Mount Sinai School of Medicine, Elmhurst Hospital Center, Elmhurst, NY.

A 60-year-old non-insulin-dependent diabetic man presented to the emergency department with acute onset of epigastric pain over the previous day; he denied any nausea, vomiting, or similar previous episodes. On examination, he was febrile to 38.7šC, tachycardic at 112, and exhibited tenderness in the right upper quadrant with localized rebound tenderness; no intra-abdominal masses were appreciated. The patient had a leukocytosis of 16,800 and elevated liver function tests: ALT 138 U/L, AST 159 U/L, GGT 338 U/L, and total bilirubin 2.4 mg/dL.

DIAGNOSIS

Gas gangrene of the gallbladder, or "emphysematous" cholecystitis

IMAGING FINDINGS

A computed tomography (CT) scan of the abdomen revealed a severely inflamed gallbladder with air in its wall and lumen consistent with "emphysematous" cholecystitis (Figure 1). No calculi were seen. The patient was fluid resuscitated, given intravenous antibiotics, and taken to the operating room for an emergent cholecystectomy (Figure 2). An intraoperative cholangiogram confirmed the absence of any stones in the biliary tree. The patient's postoperative course was unremarkable.

DISCUSSION

We report a case of a 60-year-old type-2 diabetic man with development of acute upper abdominal discomfort and emesis; he was found to have gas gangrene of the gallbladder by CT scan. This radiologic diagnosis guided us in prompt fluid resuscitation, use of intravenous antibiotics, and an emergent cholecystectomy.

Gas gangrene of the gallbladder, or em-physematous cholecystitis, was first described as gas in the gallbladder wall and bile ducts, from an autopsy specimen by Stolz in 1901 and radiographically by Hegner in 1931 (as reviewed by Wu et al ¹ ). Emphysematous cholecystitis is a distinct clinical entity from acute cholecystitis. Unlike acute cholecystitis, emphysematous cholecystitis results from thrombosis or occlusion of the cystic artery with ischemic necrosis of the gallbladder wall. ² This resulting necrosis allows gas-producing bacilli to grow, leading to emphysematous changes in the gallbladder wall. It has a characteristic acute onset, is more common in males (approximate ratio is 3 to 1), has a high preponderance in diabetics and, unlike in acute cholecystitis, is not commonly associated with gallstones. It is associated with a higher rate of perforation and, thus, a higher mortality rate when compared with acute cholecystitis. ¹ The inciting injury is probably due to a primary vascular occlusive event of the cystic artery, as endarteritis obliterans has been reproducibly seen from pathology specimens followed by superinfection with a gas-producing bacillus. ³ It is characterized by air throughout the gallbladder wall and lumen in the absence of an abnormal communication between the biliary and gastrointestinal tracts. Pneumobilia extending into the intrahepatic bile ducts is a more severe form of emphysematous cholecystitis. Early diagnosis is crucial, thereby minimizing the risk of perforation and dissemination of an anaerobic infection, which could potentially lead to multisystem organ failure.

Although ultrasound remains the recognized initial test of choice for studying the hepatobiliary tree, CT scanning is the most sensitive modality for diagnosing emphysematous cholecystitis. In a recent published series of 8 patients, ultrasound misdiagnosed 3 patients. ²

SUMMARY

Gas gangrene of the gallbladder, or em-physematous cholecystitis, is a rare but severe variant of acute cholecystitis characterized by the presence of gas in the gallbladder wall, lumen, pericholecystic areas, and possibly the biliary tree. Given this virulent disease process, we advocate early definitive treatment after diagnosis of emphysematous cholecystitis, as have others. ^1,4 Others have shown that laparoscopic cholecystectomy can be performed safely, ⁵ but given the progressive infection, we advocate a low-threshold for performing the emergent cholecystectomy through an open approach in order to safely identify biliary tree structures. Prompt radiologic diagnosis will guide the clinical management of the patient.