USMLE Prep - Medical Reference Library

Acute Mesenteric Ischemia — CTA First, Anticoagulation, and Revascularization

System: General Surgery • Reviewed: Aug 31, 2025 • Step 1Step 2Step 3

Synopsis:

Severe abdominal pain out of proportion to exam demands urgent CT angiography; resuscitate, correct precipitants, start anticoagulation, and coordinate endovascular or open revascularization with bowel viability assessment.

Key Points

  • Stabilize ABCs; treat life‑threatening derangements immediately.
  • Confirm diagnosis early with highest‑yield imaging/labs.
  • Initiate guideline‑based therapy and escalate by response.
  • Plan disposition and follow‑up explicitly.

Clinical Synopsis & Reasoning

Suspect AMI with severe, diffuse pain out of proportion to exam, especially in AF, recent MI, low‑flow states, or vasoconstrictor exposure. Obtain CTA urgently. Begin heparin anticoagulation, broad antibiotics, and hemodynamic optimization while arranging endovascular thrombectomy/stenting for SMA occlusion, vasodilators for vasospasm, and exploratory laparotomy if peritonitis, perforation, or necrosis is suspected. Consider planned second‑look laparoscopy.

Treatment Strategy & Disposition

Suspect AMI with severe, diffuse pain out of proportion to exam, especially in AF, recent MI, low‑flow states, or vasoconstrictor exposure. Obtain CTA urgently. Begin heparin anticoagulation, broad antibiotics, and hemodynamic optimization while arranging endovascular thrombectomy/stenting for SMA occlusion, vasodilators for vasospasm, and exploratory laparotomy if peritonitis, perforation, or necrosis is suspected. Consider planned second‑look laparoscopy.

Epidemiology / Risk Factors

  • Risk varies by comorbidity and precipitating factors

Initial Targets

ParameterTarget/Action
HemodynamicsMaintain perfusion; avoid hypotension
MonitoringSerial exam, labs, and imaging
TherapyStart early, reassess, de‑escalate when appropriate

Investigations

TestRole / RationaleTypical FindingsNotes
CBCScreen leukocytosis/anemiaContext‑specificTrend response
BMPElectrolytes/renal functionDerangements commonReplace K+/Mg2+
Key imagingCondition‑specific (CTA/MRI/Endoscopy)See textDo not delay when red flags

Pharmacology

MedicationMechanismOnsetRole in TherapyLimitations
Unfractionated heparinAnticoagulantImmediatePrevent propagationProtocolized aPTT
Broad‑spectrum antibioticsVariousVariableTranslocation/prophylaxisDe‑escalate with cultures

Prognosis / Complications

  • Outcome depends on timeliness of diagnosis and definitive therapy

Patient Education / Counseling

  • Explain red flags, adherence, and follow‑up plan

References

  1. WSES 2022 AMI Guideline — Link
  2. WSES 2022 AMI Guideline (PDF) — Link