Description

• More common in the elderly; can affect patients of all ages
• IC is self-limited and reversible in 80% of patients:
  • 20% of patients progress to full-thickness necrosis requiring surgical intervention.
• Most commonly, ischemia is related to a nonocclusive reduction in blood flow.
• Presentation varies, but patients with acute IC typically present with localized abdominal pain and tenderness. Frequent loose, bloody stools may be seen within 12 to 24 hours of onset.
• Laboratory and radiographic findings are nonspecific and must be correlated with clinical presentation.
• Colonoscopy is the gold standard for diagnosis of IC.
• Most patients recover with supportive care (IV fluids, bowel rest, and clinical monitoring).

Epidemiology

• More common in women (57–76%—particularly after age 69 years) (1)
• Evidence of IC is seen in 1 of every 100 endoscopies.

Geriatric Considerations
Rare in patients <60 years old; average age at diagnosis is 70 years.

Incidence
Approximately 23 cases per 100,000 person-years (ranges from 4.5 to 44) in the general population (may be underestimated due to nonspecific clinical manifestations)

Prevalence
19 cases per 100,000 in the general population

Etiology and Pathophysiology

• Local colonic hypoperfusion compromises the ability to meet metabolic demands. Reperfusion injury may also play a role.
• The colon is perfused by both the superior and inferior mesenteric arteries (SMAs and IMAs) and branches of the internal iliac arteries. Occlusion of larger branches of the SMA or IMA rarely leads to ischemic consequences due to extensive collateral circulation.
• Watershed areas of the colon (splenic flexure and rectosigmoid junction) are supplied by narrow terminal branches of the SMA and IMA, respectively, and are most susceptible to ischemic damage.
• The left colon is more commonly affected than the right; isolated right-sided disease has the worst prognosis.
• The rectum is often spared because of additional blood supply from the internal iliac arteries.
• Type I: unidentified etiology
  • Likely small vessel disease; treat supportively.
• Type II: etiology identified
  • Treat the underlying cause (1).
    • Hypoperfusion from shock, trauma
    • Embolic occlusion of mesenteric vessels
    • Hypercoagulable states, vasculitis; sickle cell disease
    • Arterial thrombosis; venous thrombosis
    • Mechanical obstruction of the colon (e.g., tumor, adhesions, hernia, volvulus, prolapse, diverticulitis)
    • Surgical complications
    • Medications (intestinally active vasoconstrictive substances, medications that induce hypotension and thus, hypoperfusion); cocaine abuse
    • Aortic dissection
    • Strenuous physical activity (e.g., long-distance running)
• Repeated episodes of ischemia and inflammation may result in chronic colonic ischemia, possible stricture formation, recurrent bacteremia, and sepsis. These patients may have unresolving areas of colitis and require segmental colonic resection.

Genetics

• Various coagulopathies have been related to IC including deficiencies of protein C, protein S, antithrombin III, and factor V Leiden mutation.
• Routine coagulation testing is not justified except in younger patients and patients with recurrent IC (1).

Risk Factors

• Age >60 years (90% of patients)
• Smoking (most common cause of recurrent IC) (1)
• Hypertension, diabetes mellitus (1)
• Rheumatologic disorders/vasculitis
• Cerebrovascular disease, ischemic heart disease (1)
• Atherosclerotic disease
• Recent abdominal surgery (i.e., ileostomy)
• Constipation, constipation-inducing medications (1)
• History of vascular surgery (1)
• Chronic obstructive pulmonary disease
• Hypoalbuminemia; hemodialysis
• Hypercoagulability, oral contraceptive (1)
• NSAID use
• Immunomodulators (1)
• IBS (1)

General Prevention

Standard practices, counseling and treatment of risk factors as indicated.