The accordion sign is seen on CT examinations of the abdomen and refers to the similarity between the thickened oedematous wall of pseudomembranous colitis to the folds of an accordion. This appearance is the result of oral contrast being trapped between oedematous haustral folds and pseudomembranes formed on the luminal surface of the colon 2.
Although it has been reported to be a specific sign of severe Clostridium difficile related colitis, it has also been described in other forms of non-specific, ischaemic, and non-clostridial infective colitis 1.
Occasionally, the hyperaemic enhancing mucosa is stretched over markedly thickened submucosal folds, simulating the accordion sign even in the absence of oral contrast material.
- 1. Fishman EK, Kavuru M, Jones B et-al. Pseudomembranous colitis: CT evaluation of 26 cases. Radiology. 1991;180 (1): 57-60. Radiology (abstract) - Pubmed citation
- 2. Macari M, Balthazar EJ, Megibow AJ. The accordion sign at CT: a nonspecific finding in patients with colonic edema. Radiology. 1999;211 (3): 743-6. Radiology (full text) - Pubmed citation