Makindo Medical Notes

Related Subjects: | Metabolic acidosis | Lactic acidosis

🚨 Mesenteric Ischaemia carries a mortality of up to 80%, even when diagnosis and treatment are prompt. Delay in recognition is the biggest killer — pain out of proportion to examination is the key clinical clue. ⚠️

📖 About

• Presentation can be acute (sudden embolus) or chronic (“abdominal angina”).
• Symptoms often outweigh signs until late → peritonitis appears once infarction occurs.
• Pathology may involve arterial thrombosis, embolism, venous thrombosis, or non-occlusive ischaemia (e.g. low flow states, vasopressors).

🩻 Anatomy

• Superior mesenteric artery (SMA) supplies midgut (duodenum → proximal 2/3 transverse colon).
• Collateral supply may temporarily mask symptoms until demand exceeds flow.

🧬 Aetiology

• Atherosclerotic thrombosis 🧱: Most common in chronic disease; often SMA origin.
• Embolism 🫀: Classically from atrial fibrillation, mural thrombus post-MI, prosthetic valves.
• Thrombophilia 🩸: Hypercoagulable states (polycythaemia, dehydration, malignancy).
• Venous occlusion: Mesenteric venous thrombosis (rare, associated with cirrhosis, OCP use, portal HTN).
• Non-occlusive ischaemia: Critically ill, shock, vasopressor therapy → gut hypoperfusion.
• Untreated → transmural necrosis ➡️ perforation ➡️ peritonitis.

👩‍⚕️ Clinical Presentation

• Acute: Sudden, severe abdominal pain out of proportion to clinical findings.
• Chronic: Post-prandial pain (intestinal angina) → fear of eating → weight loss.
• Diarrhoea (may be bloody), nausea, vomiting.
• Late: Peritonitis, sepsis, shock.

🧪 Investigations

• Bloods: Elevated WCC, CRP, renal impairment (prerenal AKI), metabolic acidosis.
• ABG: Raised lactate = ischaemia/necrosis ⚠️.
• AXR: Non-specific; may show dilated loops or “thumb-printing”.
• ECG: Check for AF/MI; troponin if suspicion.
• CT Angiography (CTA) 📊: Investigation of choice → detects vessel occlusion, pneumatosis, portal venous gas.
• Catheter Angiography: Gold standard, also therapeutic (thrombectomy, vasodilators).

💊 Management

• Immediate resuscitation: Oxygen, IV fluids, broad-spectrum antibiotics, NG decompression.
• Anticoagulation: IV heparin if embolic/thrombotic origin suspected.
• Emergency Surgery 🪡: Laparotomy + resection of necrotic bowel; sometimes “second look” laparotomy at 24–48 hrs.
• Endovascular: Angioplasty, embolectomy, or intra-arterial vasodilators for non-occlusive ischaemia.
• Palliative care: In frail patients with extensive infarction and poor prognosis.

⚖️ Prognosis & Key Teaching Points

• Mortality is high due to diagnostic delay → think early in elderly with AF + abdominal pain.
• Pain out of proportion to signs = classic exam and clinical red flag 🚨.
• CTA has replaced plain AXR as the main diagnostic test.
• Early anticoagulation and surgery save lives; late presentation often fatal.

📚 References

• NEJM – Mesenteric Ischaemia Review
• StatPearls: Mesenteric Ischaemia