Ischaemic Bowel

Overview – Ischaemic Bowel

Ischaemic bowel refers to intestinal hypoperfusion leading to bowel infarction, most commonly caused by mesenteric thromboembolism. This surgical emergency typically presents with sudden, severe abdominal pain out of proportion to clinical signs and can progress rapidly to peritonitis, sepsis, and death if not managed swiftly. Prompt recognition, reperfusion, and, if necessary, surgical resection are critical in reducing mortality.

Definition

A condition caused by reduced or blocked blood flow to the intestines, resulting in intestinal ischaemia and potentially leading to infarction and necrosis.

Aetiology

• Mesenteric thromboembolism
  • Atrial fibrillation
  • Atherosclerosis
• Aortic dissection
  • Occlusion of the coeliac trunk, SMA, or IMA
• Segmental strangulation
  • Hernia
  • Volvulus

Pathogenesis

• Vascular occlusion → impaired perfusion → tissue hypoxia → bowel ischaemia
• Prolonged ischaemia leads to necrosis, perforation, and systemic inflammatory response

Clinical Features

Early Presentation

• Sudden, severe peri-umbilical abdominal pain
• Nausea, vomiting
• Urgency to defecate
• Haematochezia (if large bowel is involved)

Late Presentation

• Signs of peritonitis: guarding, rigidity, rebound tenderness
• Abdominal distension
• Absent bowel sounds

Investigations

• ECG – to assess for atrial fibrillation
• Coagulation screen – for hypercoagulability
• Abdominal X-ray – may show thickened bowel wall, pneumatosis intestinalis
• CT scan – best for diagnosis and severity assessment
• Mesenteric angiogram – gold standard for vascular mapping
• ABG – may reveal metabolic acidosis and elevated lactate

Management

Reperfusion Strategies

• Anticoagulation: Warfarin with Heparin cover
• Thrombolysis: Tissue plasminogen activator (tPA)

Supportive Measures

• NG tube for decompression
• Antibiotics: Triple therapy (Ampicillin + Gentamicin + Metronidazole)

Surgery

• Indicated if signs of peritonitis or perforation
• Bowel resection ± colostomy

Adjuncts

• Beta-blockers (e.g. Carvedilol) if haemodynamically stable and indicated
• Digoxin if atrial fibrillation is a contributing factor

Complications

• Bowel perforation
• Sepsis
• Lactic acidosis

Summary – Ischaemic Bowel

Ischaemic bowel is a surgical emergency that results from compromised blood flow to the intestines, leading to infarction. Hallmark features include sudden severe abdominal pain, metabolic acidosis, and peritonitis. Early diagnosis with CT and angiography, along with rapid anticoagulation, thrombolysis, and surgical intervention when required, is essential. For related topics, explore our Gastrointestinal Overview page.