Overview

Ischemic colitis is a condition in which reduced blood flow to the large intestine causes inflammation, injury and, in severe cases, tissue death. It is the most common form of intestinal ischemia and is seen predominantly in older adults. Presentation can vary from mild, self‑limited episodes to fulminant disease requiring surgery.

Causes and pathophysiology

The colon is susceptible to low blood flow because some regions lie at vascular "watershed" zones where arterial supply is relatively tenuous. Injury results when oxygen delivery fails to meet tissue demand. Typical mechanisms include:

  • Nonocclusive hypoperfusion from systemic low blood pressure, dehydration, heart failure or shock.
  • Occlusive events such as arterial embolism, thrombosis, or severe atherosclerotic narrowing.
  • Local factors including vasospasm, certain medications, or iatrogenic injury after vascular procedures.

Watershed areas classically affected are the splenic flexure and the rectosigmoid junction, though any colonic segment can be involved.

Clinical features and diagnosis

Symptoms commonly include sudden abdominal pain (often left-sided), an urgent need to pass stool, and bloody diarrhea. Fever and tenderness may be present. Laboratory tests are nonspecific. Computed tomography can show bowel wall thickening and reduced enhancement; colonoscopy is the preferred diagnostic test when safe, showing pale or friable mucosa, segmental findings and, in advanced cases, ulceration or gangrene.

Management and prognosis

Treatment depends on severity. Many patients with mild, nontransmural ischemia recover with supportive care: bowel rest, intravenous fluids, correction of underlying causes and broad‑spectrum antibiotics in selected cases. Surgical resection is required for persistent ischemia, perforation or gangrene. Prognosis is generally favorable for mild cases but worse when full‑thickness infarction or comorbid illness is present.

Risk factors, prevention and distinctions

Risk factors include advanced age, cardiovascular disease, low blood flow states and certain medications that reduce mesenteric perfusion. Prevention focuses on optimizing cardiac output and hydration and careful management around vascular procedures. Important distinctions include infectious or inflammatory colitides and diverticulitis; diagnosis often relies on clinical context and endoscopic appearance.

For clinical guidelines and further reading see relevant resources.