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Colitis, Ischemic

Basics

  • Decreased blood flow to colon → inflammation and injury.
  • Common in elderly; reversible in ~80%, 20% progress to necrosis requiring surgery.
  • Most ischemia due to nonocclusive hypoperfusion.
  • Watershed areas (splenic flexure, rectosigmoid junction) most vulnerable.
  • Left colon more commonly affected; right-sided ischemia has worse prognosis.
  • Rectum often spared due to collateral blood supply.

Epidemiology

  • More common in women (57-76%), average age 70 years.
  • Incidence ~23 cases/100,000 person-years.
  • Rare under 60 years old.

Etiology & Pathophysiology

  • Local hypoperfusion and reperfusion injury.
  • Causes include small vessel disease (Type I), hypoperfusion, embolism, thrombosis, vasculitis, mechanical obstruction, medications, aortic dissection, strenuous exercise.
  • Recurrent ischemia → chronic colitis, strictures, sepsis.
  • Genetic thrombophilias (Protein C/S deficiency, factor V Leiden) linked in young/recurrent cases.

Risk Factors

  • Age >60, smoking (most common for recurrence), hypertension, diabetes, vasculitis, CVD, recent abdominal surgery, constipation-inducing drugs, NSAIDs, immunomodulators, IBS, hemodialysis, COPD.

Diagnosis

History

  • Sudden localized abdominal pain, tenderness.
  • Urge to defecate, followed by bright red or maroon stool within 12-24 hours.
  • Lower GI bleeding usually mild.

Physical Exam

  • Poorly predictive.
  • Possible hypotension, tachycardia.
  • Tenderness over affected colon segment.
  • Abdominal distension, vomiting if ileus.
  • Peritoneal signs if transmural ischemia.

Differential Diagnosis

  • Infectious colitis
  • IBD (Crohn's, UC)
  • Colon cancer
  • Diverticulitis
  • Pseudomembranous colitis

Diagnostic Tests

  • Labs: leukocytosis, metabolic acidosis, elevated lactate, LDH, CPK, alkaline phosphatase, hypoalbuminemia.
  • Imaging: Abdominal X-ray (thumbprinting), CT abdomen with contrast (colonic wall thickening, fat stranding, pneumatosis).
  • Colonoscopy: Gold standard; findings include mucosal hemorrhage, edema, segmental distribution, rectal sparing.
  • Stool studies to rule out infection.
  • Cardiac workup if embolic source suspected.
  • Avoid routine biopsy; nonspecific findings.
  • Vascular imaging if right-sided disease.

Treatment

General Measures

  • Supportive care in most cases:
  • Bowel rest
  • IV fluids
  • Avoid vasoconstrictive drugs and corticosteroids.
  • Nasogastric decompression if ileus.
  • Serial imaging and exams to monitor.

Medications

  • Broad-spectrum antibiotics covering aerobes and anaerobes (e.g., ciprofloxacin + metronidazole).
  • Avoid constipation-inducing meds (opioids), immunomodulators, and illicit drugs.

Surgery

  • Indicated in ~20% for peritonitis, shock, lactic acidosis, renal failure, persistent bleeding.
  • Most common surgery: colectomy with end ileostomy.
  • Cholecystectomy may prevent resuscitation-related acute acalculous cholecystitis.

Complementary & Alternative Medicine

  • Ginkgo biloba adjunct studied.
  • Weight loss/herbal supplements may cause IC.

Admission & Nursing

  • ICU patients difficult to diagnose due to comorbidities.
  • Bedside colonoscopy may be needed in critically ill.

Ongoing Care

  • Monitor vitals, abdominal exams, CBC, stool output.
  • Bowel rest until symptom resolution.
  • Parenteral nutrition if prolonged bowel rest needed.

Patient Education

  • Risks with weight loss and herbal supplements.
  • Smoking cessation and cardiovascular risk management reduce recurrence.

Prognosis

  • Symptoms resolve in 24-48 hours in most.
  • Radiographic/endoscopic healing by 2 weeks.
  • Right-sided IC has worse outcomes (2x mortality).
  • Poor prognostic factors: male sex, anemia, hypoalbuminemia, high BUN, metabolic acidosis.
  • Comorbid CKD, COPD, long-term care status increase mortality.
  • 20-30% develop chronic ischemic colitis requiring surgery.

Clinical Pearls:

  • Suspect IC in elderly with abdominal pain + bloody stools.
  • Colonoscopy is diagnostic gold standard.
  • Most cases resolve with supportive care; surgery if deterioration.
  • Avoid corticosteroids and vasoconstrictive drugs in IC.