Pseudomembranous colitis

Case contributed by Melbourne Uni Radiology Masters


Diarrhea, worsening abdominal pain.

Patient Data

Age: 65 years
Gender: Female

CT Abdomen and pelvis


Mural thickening and submucosal edema of the entire colon, measuring up to 12 mm at the cecum. There is a normal enhancement of the colonic mucosa except in the ascending colon where there are small areas of hypoenhancement. Large volume of intermediate density (16HU) free intraperitoneal fluid predominantly in the perihepatic, perisplenic and pelvic spaces. No dilated loops of bowel. No free intraperitoneal gas.

Heterogeneous enhancement of the spleen is likely due to late arterial phase (no opacification of hepatic veins, incomplete enhancement of renal cortex). The remainder of the intra-abdominal and pelvic organs are unremarkable. IDC in situ.

Old wedge compression fractures of T9, T10 and L1. Sclerotic lesion in T8. Bilateral pleural effusions. Right basal consolidation.

Conclusion: Mural thickening and submucosal edema of the entire colon in keeping with colitis, likely pseudomembranous given the clinical history. Small areas of hypoenhancing mucosa in the ascending colon raise the possibility of necrosis. Ischemia may be contributing, however, the SMA is seen to opacify normally.

Case Discussion

Clostridioides difficile was positive in this patient in keeping with a diagnosis of pseudomembranous colitis.

This is a common cause of antibiotic-associated diarrhea, and increasingly encountered in sick hospitalized patients. If undiagnosed and untreated, it continues to have high mortality. It may be classified as a form of infectious colitis.

Other causes of toxic megacolon and colitis include:

  • neutropenic colitis
  • inflammatory bowel disease
    • ulcerative colitis
    • Crohn disease
  • ischemic colitis
  • radiation-induced colitis
  • colonic lymphoma: also causes "thumbprinting"

If there is a history of bone marrow transplantation and the bowel involvement is not limited to the colon, then consider:

  • gastrointestinal graft-versus-host disease

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