Suspected Acute Mesenteric Ischaemia (Adult)
Severe abdominal pain out of proportion to examination: treat as AMI until proven otherwise
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Vascular SurgeryEmergency
Acute Mesenteric Ischemia - Vascular Approach (WSES 2022)
Acute Mesenteric Ischemia - Vascular Approach (WSES 2022): Suspected Acute Mesenteric Ischaemia (Adult) → Clinical Recognition → Immediate Resuscitation...
Pathway Overview
20 steps
Algorithm Steps
20 total
01Start 02Action Clinical Recognition
Keep a high index of suspicion. No blood test rules AMI in or out.
- Sudden severe pain, often with vomiting or diarrhoea; blood in stool later
- Risk factors: AF, recent MI, heart failure, atherosclerosis, previous post-meal pain or weight loss, thrombophilia
- ICU or sedated patient: new organ failure, rising vasopressor need, distension or GI bleeding may be the only signs
- Peritonitis is a late sign (transmural necrosis)
- A normal lactate or D-dimer does not exclude AMI; a raised amylase can mislead to pancreatitis
03Action Immediate Resuscitation
Start at once, in parallel with CTA. Call general surgery, vascular surgery, interventional radiology and ICU.
- IV crystalloid and blood products as needed; avoid fluid overload
- Check potassium and acid-base: hyperkalaemia and metabolic acidosis are common
- Broad-spectrum IV antibiotics now
- Vasoconstrictors reduce gut blood flow: use the lowest effective dose, but never withhold a vasopressor needed for shock
- Nasogastric decompression; nil by mouth
- ICU or HDU care; trend lactate
04Action Urgent CT Angiography
Do not delay CTA for AKI, a raised creatinine or a previous contrast reaction.
- Write "suspected acute mesenteric ischaemia" on the request
- Arterial and portal venous phases, 1 mm slices or thinner; no oral contrast
- Previous contrast reaction: do not delay; the radiologist advises on urgent premedication
- Look for SMA or SMV occlusion, poor bowel wall enhancement, pneumatosis, portal venous gas and aortic dissection
- No 24/7 vascular and interventional radiology service: arrange urgent transfer to a centre that has one
05Warning Before Heparin: Check for Bleeding, Recent Stroke, Dissection and HIT
Give heparin once CTA shows AMI. Heparin must not delay CTA, revascularisation or surgery. Aortic dissection on CTA: urgent vascular surgery; follow the aortic dissection pathway.
- Active bleeding, recent intracranial haemorrhage or stroke, or aortic dissection: no full-dose heparin until a senior clinician decides
- Previous heparin-induced thrombocytopenia: no heparin; use a non-heparin anticoagulant (haematology advice)
- On warfarin or a DOAC: record the last dose and INR; plan heparin timing and any reversal with the surgeon and haematology; do not delay surgery
06Action AMI on CTA: Start Heparin
Therapeutic IV unfractionated heparin infusion for all types of AMI
- Dose: local weight-based UFH protocol
- UFH is preferred: short-acting, reversible and usable in AKI
- Continue through intervention or surgery
- Monitor APTT or anti-Xa and platelets per local protocol
07Decision CTA: Which Type of AMI?
The type decides treatment. Each next step names its type.
- Arterial embolus: AF, sudden onset, no earlier symptoms
- Arterial thrombosis: atherosclerosis, earlier post-meal pain, weight loss
- Venous (MVT): thrombus in the SMV or portal vein
- NOMI: shock or vasopressors, patent vessels, bowel wall changes
- CTA not diagnostic but suspicion remains
- Arterial
08Decision Arterial (SMA) Occlusion: Peritonitis or Bowel Infarction on CT?
Embolic or thrombotic SMA occlusion
- Peritoneal signs
- CT: absent bowel wall enhancement, pneumatosis with portal venous gas, or free air
- If Yes
09Warning Arterial AMI With Peritonitis or Infarction: Emergency Laparotomy
Revascularise the SMA first, then resect. Massive necrosis or frailty: discuss goals of care (palliation may be right) before surgery.
- Hybrid theatre if available; restore SMA flow before any bowel resection
- Resect only clearly necrotic bowel; no anastomosis; temporary abdominal closure
- No vascular service on site: resect necrotic bowel sparingly, close temporarily and transfer for revascularisation
10Action Open or Hybrid SMA Revascularisation
At laparotomy, or when endovascular treatment is not possible or fails
- Embolus: SMA embolectomy through a transverse arteriotomy (balloon catheter)
- Thrombosis on a stenosis: retrograde open mesenteric stenting or bypass
- Patient in extremis or no vascular skills: temporary SMA shunt
- Completion imaging: angiography or duplex
- Reassess the bowel after reperfusion (ICG fluorescence can help)
11Warning After Laparotomy: Planned Second Look
At 24-48 h after revascularisation with bowel resection, when bowel viability is doubtful, or when the patient does not improve
- Resect only clearly non-viable bowel; leave doubtful bowel for the next look
- Make anastomosis or stoma at the second or third look, when stable
- Laparoscopic second look is an option in selected patients
12Action ICU and Ongoing Care
Aim: gut perfusion and prevention of organ failure
- Correct acidosis, hypothermia and coagulopathy; limit crystalloid (abdominal compartment syndrome)
- Vasopressor needed: noradrenaline with or without dobutamine is preferred to vasopressin
- Continue heparin; continue antibiotics by contamination and cultures
- Long term: anticoagulation (embolism, MVT); after SMA stent, antiplatelet therapy per vascular team
- Imaging surveillance (CTA or duplex) within 6 months of revascularisation
- Nutrition support; watch for short bowel syndrome
- Treat the cause: AF, cardiac source of embolus, thrombophilia
13Outcome Survival and Follow-Up
Long-term antithrombotic therapy, imaging surveillance and risk factor control
14Outcome Short Bowel Syndrome
After extensive resection: refer early to an intestinal failure unit (parenteral nutrition, GLP-2 analogue, restore continuity)
If No15Warning No Peritonitis or Infarction: Check Thrombolysis Contraindications
Before any SMA thrombolysis. If a contraindication is present: aspiration or mechanical thrombectomy, or open surgery.
- Peritonitis or bowel infarction on CT; active bleeding or bleeding disorder
- Stroke or TIA in the last 2 months; GI bleeding in the last 10 days; recent surgery, trauma or CPR
- Uncontrolled hypertension (above 180/110 mmHg); liver failure with coagulopathy; pregnancy
16Action Arterial AMI, No Peritonitis or Infarction: Endovascular Revascularisation First
First line for embolic or thrombotic SMA occlusion where expertise is available
- Aspiration embolectomy
- Stent the underlying stenosis (thrombotic occlusion)
- Local SMA thrombolysis only for residual or distal clot, and only with no contraindication
- Persisting peritonism or worsening after the procedure: laparotomy without delay
- Not possible or failed: open or hybrid revascularisation (see above)
- Path rejoins step 12Shared downstream outcome
- Venous
17Action Mesenteric Venous Thrombosis: Anticoagulation First
No peritonitis: heparin and non-operative care. Peritonitis: laparotomy. Endovascular lysis only if worsening and no lysis contraindication.
- Therapeutic UFH or LMWH now; UFH if surgery or intervention is likely, or with AKI
- Peritonitis: laparotomy; resect only necrotic bowel; second look at 24-48 h
- Worsening on anticoagulation: consider endovascular venous thrombolysis or thrombectomy (specialist centre); not with active bleeding, recent stroke, surgery or trauma, or liver failure with coagulopathy
- Then 3-6 months of warfarin or LMWH; a DOAC is an alternative, but not in pregnancy, antiphospholipid syndrome or Child-Pugh C cirrhosis (rivaroxaban: also not Child-Pugh B); indefinite if unprovoked or a permanent risk factor
- Look for a cause: cancer, inflammatory disease, myeloproliferative neoplasm, liver disease; thrombophilia tests in selected patients
- Nasogastric decompression and bowel rest
- Path rejoins step 12Shared downstream outcome
- NOMI
18Action Non-Occlusive Mesenteric Ischaemia (NOMI): Treat the Cause
Critically ill patient, patent vessels on CTA. Restore perfusion; operate for necrosis.
- Treat the cause; fluids; optimise cardiac output; if a vasopressor is needed, noradrenaline with or without dobutamine rather than vasopressin
- Reduce vasoconstrictors when possible; never stop a vasopressor needed for shock
- Abdominal compartment syndrome: urgent decompression laparotomy
- Peritonitis, perforation or worsening: laparotomy and resect necrotic bowel (damage control)
- Consider SMA catheter vasodilator under heparin (adult, specialist IR): papaverine 120 mg/10 mL, 80 mg bolus, then 30-60 mg/h for 24-72 h; risk of sudden hypotension
- Path rejoins step 12Shared downstream outcome
- Not diagnostic
19Action CTA Not Diagnostic but Suspicion Remains
Early AMI and NOMI can be missed on CTA
- Senior radiologist and surgeon review the images together
- Critically ill: consider NOMI; angiography or diagnostic laparoscopy
- Peritonitis: laparotomy
- Other cause found: treat it
20Outcome Reassess Often
Repeat examination and lactate trend; escalate at once if worse
Guideline Source
WSES 2022 Acute Mesenteric Ischemia: Updated Guidelines (Bala et al.), with ESVS 2025 Mesenteric and Renal Arteries and Veins Guidelines
Clinical Safety Information
Clinical Decision Support — Not a Substitute for Clinical Judgment
Individual patient factors may require deviation from these recommendations.
Known Limitations
- Adults only. Time-critical: each 6 h of delay to CTA doubles mortality; transfer early if 24/7 vascular and interventional radiology services are not available.
- Evidence is mostly low quality and observational; mortality stays high (about 30-70%). Choice of open or endovascular technique depends on local expertise.
- Heparin, thrombolytic and antithrombotic doses follow local protocols and specialist advice.
- Intra-arterial vasodilator therapy for NOMI has weak evidence (ESVS 2025 class IIb).
Contraindicated Populations
pediatric
Applicable Regions
AUEUUSGlobal
AU: Papaverine hydrochloride 120 mg/10 mL injection is on the ARTG. Transfer to a centre with 24/7 vascular and interventional radiology services.
EU: ESVS 2025 mesenteric and renal guidelines (co-source) replace ESVS 2017: endovascular revascularisation first for SMA occlusion (Rec 37).
US: Management principles consistent with WSES 2022.
Version 2Next review: 2027-09-30
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Related Resources
Frequently Asked Questions
What is the Acute Mesenteric Ischemia - Vascular Approach (WSES 2022)?
The Acute Mesenteric Ischemia - Vascular Approach (WSES 2022) is a emergency clinical algorithm for Vascular Surgery. It provides a structured decision tree to guide clinical decision-making, based on WSES 2022 Acute Mesenteric Ischemia: Updated Guidelines (Bala et al.), with ESVS 2025 Mesenteric and Renal Arteries and Veins Guidelines.
What guideline is the Acute Mesenteric Ischemia - Vascular Approach (WSES 2022) based on?
This algorithm is based on WSES 2022 Acute Mesenteric Ischemia: Updated Guidelines (Bala et al.), with ESVS 2025 Mesenteric and Renal Arteries and Veins Guidelines (DOI: 10.1186/s13017-022-00443-x).
What are the limitations of the Acute Mesenteric Ischemia - Vascular Approach (WSES 2022)?
Known limitations include: Adults only. Time-critical: each 6 h of delay to CTA doubles mortality; transfer early if 24/7 vascular and interventional radiology services are not available.; Evidence is mostly low quality and observational; mortality stays high (about 30-70%). Choice of open or endovascular technique depends on local expertise.; Heparin, thrombolytic and antithrombotic doses follow local protocols and specialist advice.; Intra-arterial vasodilator therapy for NOMI has weak evidence (ESVS 2025 class IIb).. Individual patient factors may require deviation from these recommendations.
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