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gi.acute-mesenteric-ischemia.core.v1

Acute Mesenteric Ischemia

vascularacuteadultacuteinpatient
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Primary guideline: WSES 2017 (Bala et al, PMID 28794797 verified via PubMed MCP 2026-05-26). CT angiography triphasic is first-line gold-standard; oral contrast is HARMFUL and must be skipped (WSES 2017). Four etiologies: arterial embolism (SMA mid-distal, AF), arterial thrombosis (proximal SMA, atherosclerosis), MVT (filling defect SMV/PV), NOMI (low-flow state). Endovascular preferred for arterial AMI without peritoneal signs; anticoagulation alone for MVT; intra-arterial papaverine for NOMI; open laparotomy for peritonitis or failed endovascular. Second-look laparotomy 24-48h after damage control if bowel viability uncertain (WSES 2017). RxCUIs verified live via RxNav 2026-05-26: heparin=5224, alteplase=8410, papaverine=7895, pip-tazo=74169, meropenem=29561, norepinephrine=7512.

Entry points (5)

  • symptom
    Severe abdominal pain out of proportion to exam findings (WSES 2017 hallmark)
    pain_out_of_proportion
  • symptom
    Sudden severe periumbilical pain with vomiting / diarrhea (SMA embolism)
    sudden_severe_abdominal_pain
  • history
    Atrial fibrillation, recent MI, or known atherosclerosis with new abdominal pain (embolic source)
    afib_or_recent_mi
  • lab_abnormality
    Unexplained lactic acidosis + abdominal pain (late finding, transmural infarction)
    unexplained_lactic_acidosis
  • imaging
    CT angiography showing mesenteric arterial occlusion, venous thrombosis, or pneumatosis intestinalis
    cta_mesenteric_occlusion

Required inputs (13)

  • agerequired
    demographic • used at CONTEXT
    Elderly + atherosclerosis = arterial; younger = venous or NOMI; influences risk (WSES 2017)
  • sbprequired
    vital • used at CONTEXT
    Hypotension drives NOMI risk and sepsis resuscitation (WSES 2017)
  • hrrequired
    vital • used at CONTEXT
    Tachycardia + AF (embolic source); shock physiology
  • temperaturerequired
    vital • used at RED_FLAGS
    Fever suggests bowel infarction or perforation (WSES 2017)
  • abdominal_pain_qualityrequired
    symptom • used at ENTRY
    Pain out of proportion = hallmark; peritoneal signs = transmural infarction (WSES 2017)
  • lactaterequired
    lab • used at INITIAL_WORKUP
    Elevation late but specific for bowel ischemia / transmural infarction (WSES 2017)
  • wbcrequired
    lab • used at INITIAL_WORKUP
    Leukocytosis (often >20,000) supports diagnosis (WSES 2017)
  • creatininerequired
    lab • used at INITIAL_WORKUP
    Contrast safety for CTA + heparin / endovascular planning
  • inrrequired
    lab • used at INITIAL_WORKUP
    Anticoagulation baseline; heparin and thrombolytic planning
  • d_dimer
    lab • used at INITIAL_WORKUP
    High sensitivity but low specificity; rules out at low value (WSES 2017)
  • cta_abdomen_pelvisrequired
    imaging • used at INITIAL_WORKUP
    CT angiography triphasic = first-line gold standard imaging; STAT (WSES 2017)
  • afib_vte_atherosclerosisrequired
    history • used at CONTEXT
    Embolic vs thrombotic vs venous vs NOMI etiology (WSES 2017)
  • current_anticoagulation
    medication • used at CONTEXT
    Reverses risk; baseline for heparin decision

12-phase flow (12)

  1. 1FRAME
    Frame: acute interruption of mesenteric blood flow leading to bowel ischemia and necrosis; 50% mortality untreated; four etiologies (arterial embolism, arterial thrombosis, mesenteric venous thrombosis, NOMI) (WSES 2017)
    inputs: age
    advance: AMI considered plausible by clinical context
  2. 2ENTRY
    Recognize pain out of proportion to exam; AF / atherosclerosis + sudden abdominal pain; unexplained lactic acidosis (WSES 2017)
    inputs: abdominal_pain_quality
    advance: one entry trigger present
  3. 3CONTEXT
    Vitals, AF/embolic source, atherosclerosis, hypercoagulable history, recent MI, anticoagulation, comorbidities, time since symptom onset (golden window) (WSES 2017)
    inputs: age, sbp, hr, afib_vte_atherosclerosis, current_anticoagulation
    advance: context captured
  4. 4RED_FLAGS
    Peritoneal signs (rigidity, rebound) = transmural infarction → emergent laparotomy; shock; lactate >2; severe metabolic acidosis (WSES 2017)
    inputs: sbp, temperature, lactate
    actions: workup.mesenteric_ischemia
    advance: peritoneal signs identified or excluded
  5. 5INITIAL_WORKUP
    CBC, BMP, lactate, INR, ABG, D-dimer; STAT CT angiography triphasic (oral contrast HARMFUL — skip); cross-match (WSES 2017)
    inputs: wbc, lactate, creatinine, inr, cta_abdomen_pelvis
    actions: panel.cbc, panel.renal, panel.coag, panel.abg, workup.mesenteric_ischemia
    advance: CTA obtained + labs returned
  6. 6BRANCHING_WORKUP
    Classify etiology by CTA: arterial embolism (SMA mid-distal), arterial thrombosis (proximal SMA + atherosclerosis), MVT (filling defect in SMV/PV), NOMI (vasoconstriction without occlusion); echocardiogram for embolic source; hypercoagulable workup for MVT in young (WSES 2017)
    advance: etiology classified
  7. 7DIFFERENTIAL
    Distinguish from acute pancreatitis, perforated viscus, ruptured AAA, intestinal obstruction, ischemic colitis, DKA, sickle cell crisis (WSES 2017)
    advance: AMI confirmed by CTA
  8. 8RISK_STRATIFICATION
    Bowel viability assessment: peritoneal signs + lactate + time from onset; transmural infarction (mortality high) vs salvageable bowel (revascularization window) (WSES 2017)
    inputs: lactate, sbp
    advance: severity tier assigned
  9. 9TREATMENT
    Immediate IV unfractionated heparin (5000 U bolus + drip); fluid resuscitation; broad-spectrum antibiotics if perforation/translocation concern; endovascular revascularization first-line for arterial AMI (WSES 2017); anticoagulation alone for MVT; vasodilator (papaverine) for NOMI + improve perfusion; emergent laparotomy if peritoneal signs / perforation
    inputs: creatinine, inr
    advance: heparin started + revascularization plan in motion
  10. 10DISPOSITION
    ICU for all confirmed AMI; OR for peritonitis or failed endovascular; IR suite for endovascular; second-look laparotomy 24-48h after damage control (WSES 2017)
    inputs: sbp
    advance: destination + procedure timing locked
  11. 11MONITORING
    Serial lactate, abdominal exam, vitals, UOP; post-revascularization reperfusion injury monitoring; second-look laparotomy 24-48h (WSES 2017)
    inputs: lactate
    advance: response documented or escalated
  12. 12FOLLOWUP
    Long-term anticoagulation per etiology (MVT lifelong if unprovoked / thrombophilia; arterial per source); short-bowel syndrome management if extensive resection; nutrition support; secondary prevention (statin, antiplatelet, AF anticoagulation) (WSES 2017)
    advance: long-term plan documented