A 68-year-old man develops sudden left iliac fossa pain and bloody diarrhoea 2 days after an episode of hypotension during hemodialysis. He is afebrile and the abdomen is soft. CT shows concentric thickening of the wall of the descending colon and splenic flexure with thumbprinting. There is no free air or portal venous gas. The most likely diagnosis is:

• A Pseudomembranous colitis
• B Ischaemic colitis ✓
• C Diverticulitis Hinchey grade II
• D Ulcerative colitis

Explanation

Ischaemic colitis follows a hypotensive event and characteristically affects watershed areas, most commonly the splenic flexure and sigmoid. Thumbprinting reflects submucosal oedema and haemorrhage, and bloody diarrhoea with disproportionate mild tenderness is typical. Pseudomembranous colitis is associated with antibiotic exposure and pancolonic involvement, while diverticulitis presents with localised peritonitis rather than bleeding as the leading feature.

Reference: Sabiston Textbook of Surgery, 21st ed.

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Written and medically reviewed by the StethoPrep medical team.