- Pseudomembranous colitis (PMC) is an acute infectious colitis caused by toxins produced by Clostridium difficile bacteria in the colon.
- C difficile infection is responsible for virtually all cases of PMC and for up to 20% of cases of antibiotic-associated diarrhea without colitis.
- PMC can result in significant patient morbidity and mortality, especially if it is not diagnosed early.
- Overall mortality rates from 1.1% to 3.5% have been reported for patients with PMC.
- The clinical features of PMC include diarrhea, abdominal tenderness, fever, dehydration, and leukocytosis.
- Endoscopy can help establish the diagnosis of PMC by demonstrating the characteristic adherent yellow plaques
- The treatment of PMC consists of oral administration of metronidazole or vancomycin, and most patients respond well within 3–4 days.
 Imaging Findings
 Plain film
- Plain radiographic findings in including colonic ileus, small bowel ileus, ascites, and nodular haustral thickening .
- Thumbprinting (unusual, wide transverse bands associated with thickening of the haustral folds) and gaseous distention of the colon have also been identified.
- Common CT findings include wall thickening, low-attenuation mural thickening corresponding to mucosal and submucosal edema, the accordion sign, the target sign, double halo sign, pericolonic stranding, and ascites.
- The target sign, which consists of two or three concentric rings of different attenuation, indicates mucosal hyperemia and submucosal edema or inflammation. The rings of varying attenuation are best appreciated during the arterial phase of enhancement.
- The accordion sign is seen when orally administered contrast material becomes trapped between markedly thickened haustral folds, giving the appearance of alternating bands of high attenuation (contrast material) and low attenuation (edematous haustra). This sign is highly suggestive of PMC, although it is usually seen only in advanced cases.
 See Also
 External Links
- Satomi Kawamoto, Karen M. Horton, and Elliot K. Fishman. Pseudomembranous Colitis: Spectrum of Imaging Findings with Clinical and Pathologic Correlation.
RadioGraphics 1999 19: 887-897.