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Acute Mesenteric Ischemia
emergencyvascular
Description
Sudden reduction in intestinal blood flow causing bowel ischemia and potentially infarction. Most commonly due to arterial embolism (50%), arterial thrombosis (25%), or non-occlusive mesenteric ischemia (20%). Mortality 60-80% if diagnosis delayed.
Key Features
- Severe abdominal pain OUT OF PROPORTION to physical exam
- Rapid onset, poorly localized pain
- Atrial fibrillation or other embolic source
- Minimal findings on early examination
- Elevated lactate (late finding)
Diagnostic Criteria
- Clinical suspicion + CT Angiography confirmation:
- High suspicion if:
- - Severe abdominal pain out of proportion to exam
- - Risk factors (AF, atherosclerosis, hypercoagulable state)
- - Rapid onset
- CT Angiography findings:
- - Arterial: filling defect in SMA or branches
- - Venous: SMV thrombosis
- - Bowel: wall thickening, lack of enhancement, pneumatosis
- - Late: portal venous gas, free air (perforation)
- KEY PRINCIPLE: Do not wait for lactate elevation — it is a LATE marker
Red Flags
- • Pain out of proportion to exam (CLASSIC)
- • Atrial fibrillation + acute abdominal pain
- • Metabolic acidosis
- • Peritoneal signs (late — bowel already infarcted)
- • Bloody stool (late sign)
Differential Clues
Severe pain with initially benign examAF or embolic risk factorsRapid onsetElevated lactate (late)CT angiography shows occlusion
Sources: DynaMed. Acute Mesenteric Ischemia. EBSCO Information Services. | European Society for Vascular Surgery Guidelines