Ischaemic bowel disease
- Lesion
When blood flow to the bowel drops, the lining dies first; a sudden block of a major artery can kill the whole wall.
What it is
The gut is supplied by the coeliac, superior mesenteric and inferior mesenteric arteries, with collaterals that tolerate slow narrowing but not sudden occlusion. Ischaemic damage ranges from mucosal infarction (above the muscularis mucosae) to mural (mucosa and submucosa) to transmural infarction of all layers. Transmural infarction usually follows acute thrombosis or embolism; mucosal and mural infarcts follow hypoperfusion. Much of the injury happens at reperfusion.
Structure
- Acute transmural infarct: sharply demarcated, intensely congested, dusky to purple-red bowel; later bloody mucus in the lumen, rubbery oedematous wall.
- Coagulative necrosis of the muscularis propria within one to four days; perforation and fibrinopurulent serositis may follow.
- Mucosal infarct: haemorrhagic, ulcerated, segmental and patchy mucosa.
- Micro: atrophic or sloughed surface epithelium, crypts preserved; neutrophils arrive after reperfusion.
- Chronic ischaemia: fibrotic lamina propria and, uncommonly, stricture; superinfection can create pseudomembranes.
Step by step
- Blood flow falls from arterial blockage, venous thrombosis or low cardiac output.
- The tips of villi and the surface epithelium become hypoxic first.
- Reperfusion brings free radicals and neutrophils, and bacterial products leak across the barrier.
- Damage deepens from mucosa to submucosa to muscle if the cause persists.
- Transmural necrosis leads to perforation, peritonitis and sepsis.
Clinical notes
- Acute colonic ischaemia: sudden cramping left lower abdominal pain, urgency and bloody diarrhoea, mostly in people over seventy.
- Acute mesenteric ischaemia: pain out of proportion to the examination; signs of infarction appear late.
- Other ischaemic patterns: CMV endothelial infection, radiation enterocolitis, necrotizing enterocolitis of premature infants.
Test yourself
Think of the answer, then tap the question to see it.
Why is the surface epithelium more vulnerable to ischaemia than the crypts?
Capillaries run from the crypt toward the surface before turning back, so the surface receives the least oxygenated blood; crypt stem cells are protected.
Which two colonic watershed zones are most prone to ischaemic colitis?
The splenic flexure and the rectosigmoid region.
What usually causes transmural intestinal infarction?
Acute arterial obstruction by thrombosis (atherosclerosis) or embolism (cardiac mural thrombus, aortic atheroma).
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Acute Mesenteric Ischemia (StatPearls (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.