<aside> 💡 Mesenteric ischemia: ischemia of small intestine Ischemic colitis: ischemia of large intestine

Both can be classified as acute or chronic

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chronic will most commonly impact poorly vascularised regions in the splenic flexure and rectosigmoid; however, it can be located throughout the colon (with the exception of the rectum, which is unaffected because it has dual blood supply)

Collateral circulation of the gastrointestinal tract can compensate for a 75% acute reduction in mesenteric perfusion for up to 12 hours without significant injury.

Aetiology

• Acute
  • mesenteric arterial embolism (50%)
  • intestinal hypoperfusion or nonocclusive mesenteric ischemia (NOMI) (20% to 30%)
  • mesenteric arterial thrombosis (15% to 25%)
  • mesenteric venous thrombosis (MVT)(5%).
• Chronic
  • 95% atherosclerosis of coeliac or superior mesenteric arteries
  • Other 5% include vasculitis, pressure from the median arcuate ligament, retroperitoneal fibrosis, fibromuscular dysplasia, Takayasu arteritis, malignancy, and radiation

Risk factors

• Females
• Age >60
• hypertension
• diabetes
• cardiovascular disease
• smoking
• coagulopathy

Clinical Features