Accordion Sign

General Considerations

• The sign was originally described as alternating edematous haustral folds separated by mucosal ridges filled with oral contrast material
• Simulated appearance of an accordion
• It was first thought to be specific for severe Clostridium difficile–related colitis (pseudomembranous colitis)
• Almost all cases of pseudomembranous colitis are associated with recent antibiotic therapy
• C. difficile is the largest single cause of this sign

Clinical Findings

• C. difficile is a gram-positive anaerobic bacillus
• Can cause a spectrum of GI diseases ranging from mild diarrhea to fulminant life-threatening colitis

Imaging Findings

• The sign is due to the marked degree of colonic wall thickening caused by the pseudomembranes and edematous tissues that develop in C difficile colitis

Differential Diagnosis

• Cirrhosis with colonic edema
• Ischemic colitis

Accordion Sign. White oval highlights markedly thickened bowel wall with oral contrast trapped between haustral folds in a patient with known C difficile colitis. This is the "accordion sign."
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The Accordion Sign at CT: a Nonspecific Finding in Patients with Colonic Edema  Macari, M; Balthazar, E and Megibow, A. Radiology June 1999 211:743-746