What is the diagnostic approach for ischemic colitis?

Diagnostic Approach for Ischemic Colitis

The diagnosis of ischemic colitis requires a combination of clinical suspicion, laboratory testing, imaging, and endoscopy with biopsy, with colonoscopy being the gold standard diagnostic procedure. 1, 2, 3

Clinical Presentation

• Common symptoms:

  • Abdominal pain (often left-sided or periumbilical)
  • Diarrhea
  • Mild lower gastrointestinal bleeding (hematochezia)
  • Urgency to defecate
  • Tenderness on abdominal examination

• Risk factors to identify:

  • Advanced age
  • Cardiovascular disease
  • Hypotension/shock states
  • Recent vascular procedures
  • Hypercoagulable states
  • Medications (vasoconstrictors, diuretics)

Diagnostic Algorithm

Step 1: Initial Laboratory Tests

• Complete blood count (CBC) - may show leukocytosis
• C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) - elevated inflammatory markers
• Electrolytes, liver function tests, and albumin
• Stool studies:
  • Fecal calprotectin or lactoferrin (to detect inflammation)
  • Stool culture and C. difficile testing (to rule out infectious causes)
  • Ova and parasites if clinically indicated 1, 4

Step 2: Imaging

• Plain abdominal radiograph:

  • May show "thumbprinting" (mucosal edema)
  • Useful to exclude toxic megacolon or perforation
  • Often not sufficiently sensitive or specific 1

• CT scan with IV contrast:

  • Most reliable imaging modality for suspected ischemic colitis
  • Findings include bowel wall thickening, "target sign," mesenteric vessel engorgement
  • Can help rule out other causes of acute abdomen 1

Step 3: Endoscopy

• Flexible sigmoidoscopy or colonoscopy:

  • Gold standard for diagnosis 1, 3
  • Should be performed within 48 hours of symptom onset
  • Full colonoscopy may be risky in acute severe cases; flexible sigmoidoscopy is often sufficient 1

• Characteristic endoscopic findings:

  • Segmental involvement (often "watershed" areas: splenic flexure, sigmoid colon)
  • Petechial hemorrhages
  • Longitudinal ulcerations
  • Pale, edematous mucosa
  • Sharply demarcated areas of involvement
  • Normal rectum (typically spared) 1

Step 4: Histopathology

• Mucosal and submucosal hemorrhage
• Inflammatory infiltrates
• Necrosis (in severe cases)
• Ghost cells (empty appearing mucosal cells)

Differential Diagnosis

• Infectious colitis (bacterial, viral, parasitic)
• Inflammatory bowel disease
• Diverticulitis
• Radiation colitis
• Medication-induced colitis
• Neutropenic enterocolitis in immunocompromised patients 1

Important Considerations

• Severity assessment:

  • Non-gangrenous (mild to moderate): Transient, self-limiting
  • Gangrenous (severe): Requires urgent surgical intervention 2, 5

• Distinguishing features from other colitides:

  • Segmental involvement with sparing of rectum (unlike ulcerative colitis)
  • Sharply demarcated areas of involvement
  • Rapid resolution on serial examinations
  • "Watershed" territory involvement (sigmoid to splenic flexure) 1

Common Pitfalls to Avoid

1. Delayed diagnosis: Maintain high clinical suspicion, especially in elderly patients with cardiovascular risk factors and abdominal pain with bloody diarrhea

2. Overreliance on laboratory tests: Laboratory findings are nonspecific and may be normal in early or mild disease 1

3. Missing gangrenous colitis: Requires urgent surgical intervention; watch for signs of peritonitis, severe pain, fever, and hemodynamic instability 5

4. Incomplete evaluation: Always perform stool studies to exclude infectious causes before attributing symptoms to ischemic colitis 4

5. Performing full colonoscopy in severe cases: May increase risk of perforation; flexible sigmoidoscopy is often sufficient and safer 1

By following this systematic diagnostic approach, clinicians can promptly identify ischemic colitis, distinguish it from other causes of colitis, and initiate appropriate management to reduce morbidity and mortality.