Overview
Mesenteric Ischaemia
1. Clinical Overview
Summary
Mesenteric ischaemia is a life-threatening condition characterized by inadequate blood supply to the intestines, leading to bowel infarction and potentially fatal complications. It occurs in acute and chronic forms, with acute mesenteric ischaemia being a surgical emergency with mortality rates of 30-90%. The condition requires high clinical suspicion, prompt diagnosis, and urgent intervention combining medical resuscitation, anticoagulation, and surgical management. Chronic mesenteric ischaemia presents as postprandial abdominal pain and weight loss, requiring elective revascularization. Early recognition is crucial as delays in diagnosis significantly worsen outcomes. [1,2]
Key Facts
- Incidence: Acute: 0.1-0.2% of acute surgical admissions; Chronic: Rare (less than 1 per 100,000).
- Mortality: Acute: 30-90% (highest of abdominal emergencies); Chronic: less than 5% with treatment.
- Age Distribution: Peak incidence 60-80 years; rare in young adults.
- Male:Female Ratio: 1:1 in acute forms; 1:3 in chronic forms.
- Hospital Stay: Survivors require 2-4 weeks ICU care on average.
- Long-term Sequelae: 20-30% develop short bowel syndrome requiring TPN.
Clinical Pearls
The Silent Killer: Mesenteric ischaemia is often called the "silent killer" because early symptoms are subtle and examination findings minimal until bowel infarction occurs.
Pain Out of Proportion: Severe abdominal pain with minimal tenderness is the classic presentation - suspect mesenteric ischaemia until proven otherwise.
The Window of Opportunity: Viable bowel can be salvaged up to 6-12 hours after onset; beyond this, resection is inevitable.
Triple Threat: Most cases involve occlusion of the superior mesenteric artery (SMA), the vessel supplying 90% of small bowel blood flow.
Why This Matters Clinically
- Surgical Emergency: Highest mortality of any abdominal emergency when missed.
- Diagnostic Challenge: Non-specific early symptoms, normal early examinations.
- Multidisciplinary Care: Requires vascular surgeons, intensivists, gastroenterologists.
- Preventable: Smoking cessation, anticoagulation, and cardiac source treatment reduce risk.
- Resource Intensive: Survivors often require prolonged ICU stay and nutritional support.
- Quality Indicator: Time to diagnosis and intervention affects hospital quality metrics.
2. Epidemiology
Global Burden
- Annual Incidence: Acute: 1-2 per 100,000 population; Chronic: 0.05-0.1 per 100,000.
- Hospital Admissions: 0.1-0.2% of acute surgical admissions present with acute mesenteric ischaemia.
- Age-Specific Rates: less than 50 years: 0.02 per 100,000; 50-70 years: 0.5 per 100,000; >70 years: 2-3 per 100,000.
- Geographic Variation: Higher in developed countries with aging populations.
- Economic Impact: $1-2 billion annually in US healthcare costs.
Risk Factors and Odds Ratios
| Risk Factor | Odds Ratio | Mechanism |
|---|---|---|
| Atrial Fibrillation | 5-10x | Cardiac thrombus source for emboli |
| Recent Myocardial Infarction | 3-5x | Left ventricular thrombus |
| Heart Failure | 2-4x | Low cardiac output states |
| Peripheral Vascular Disease | 3-6x | Atherosclerotic burden |
| Smoking | 2-3x | Endothelial damage, thrombosis |
| Diabetes Mellitus | 2x | Atherosclerosis acceleration |
| Hyperlipidemia | 1.5-2x | Atherosclerotic plaque formation |
| Chronic Kidney Disease | 2-3x | Uremic vasculopathy |
| Oral Contraceptives | 2x | Hypercoagulable state (young women) |
| Malignancy | 1.5-2x | Hypercoagulable state, chemotherapy |
Aetiological Distribution
Acute Mesenteric Ischaemia (AMI):
- Arterial Embolism: 40-50% - SMA occlusion from cardiac sources.
- Arterial Thrombosis: 20-30% - Atherosclerotic plaque rupture.
- Venous Thrombosis: 5-15% - Mesenteric vein thrombosis.
- Non-Occlusive: 20-25% - Low flow states in shock/critical illness.
Chronic Mesenteric Ischaemia (CMI):
- Atherosclerosis: 80-90% - Stenosis of ≥2 mesenteric vessels.
- Vasculitis: 5-10% - Takayasu's, PAN, SLE.
- Fibromuscular Dysplasia: 2-5% - Young women.
- Median Arcuate Ligament Syndrome: 2-3% - Celiac compression.
Outcomes and Mortality
- Overall Mortality: AMI: 60-80%; CMI: less than 5% with treatment.
- Early Diagnosis: Mortality 30-50% if diagnosed within 24 hours.
- Late Diagnosis: Mortality >90% if diagnosed after 48 hours.
- Bowel Resection: Required in 70-80% of AMI cases.
- Short Bowel Syndrome: Occurs in 20-30% of survivors.
3. Pathophysiology
Step 1: Vascular Occlusion or Hypoperfusion
- Arterial Embolism: Cardiac thrombus (AF, post-MI) embolizes to SMA.
- Arterial Thrombosis: Atherosclerotic plaque rupture with thrombosis.
- Venous Thrombosis: Mesenteric vein thrombosis from hypercoagulable states.
- Hypoperfusion: Shock states reduce splanchnic blood flow.
Step 2: Ischaemic Cascade Initiation
- Oxygen Deprivation: Mucosal cells most susceptible (anaerobic metabolism).
- ATP Depletion: Cellular energy failure within minutes.
- Ion Pump Failure: Sodium-potassium pump dysfunction.
- Cellular Swelling: Intracellular edema, mucosal barrier breakdown.
Step 3: Mucosal and Submucosal Injury
- Increased Permeability: Loss of tight junctions, bacterial translocation.
- Inflammatory Response: Cytokine release (TNF-α, IL-6), neutrophil infiltration.
- Acid-Base Imbalance: Lactic acid production, metabolic acidosis.
- Vasodilation: Compensatory response attempting to improve flow.
Step 4: Transmural Necrosis
- Full-Thickness Injury: All bowel layers affected.
- Bacterial Invasion: Gut flora enter bloodstream and peritoneal cavity.
- Peritonitis: Chemical and bacterial peritonitis.
- Sepsis: Systemic inflammatory response, multiorgan dysfunction.
Step 5: Systemic Complications
- Cardiovascular Collapse: Septic shock, cardiac depression.
- Acute Respiratory Distress: Pulmonary edema, ARDS.
- Acute Kidney Injury: ATN from hypoperfusion and sepsis.
- Disseminated Intravascular Coagulation: Consumption coagulopathy.
Pathophysiological Variants
Arterial Embolism:
- Sudden onset, watershed distribution.
- Jejunum spared (arcades), ileum/colon affected.
Arterial Thrombosis:
- Progressive atherosclerosis, acute thrombosis.
- Extensive small bowel involvement.
Venous Thrombosis:
- Gradual onset, entire bowel wall affected.
- More edema, less hemorrhage.
Non-Occlusive Mesenteric Ischaemia (NOMI):
- Diffuse vasoconstriction in critically ill.
- Multiple small infarcts, patchy involvement.
4. Clinical Presentation
Acute Mesenteric Ischaemia
Classic Triad:
Symptoms by Frequency
| Symptom | Frequency (%) | Notes |
|---|---|---|
| Abdominal Pain | 90-100 | Sudden onset, severe, constant |
| Nausea/Vomiting | 60-70 | Early sign, may be bilious |
| Diarrhea | 50-60 | Often bloody, small volume |
| Anorexia | 40-50 | Recent onset |
| Weight Loss | 30-40 | If chronic component |
| Dyspnea | 20-30 | If pulmonary edema |
| Syncope | 10-20 | Due to pain or hypovolemia |
Signs and Examination Findings
Early Phase (0-6 hours):
Intermediate Phase (6-12 hours):
Late Phase (>12 hours):
Chronic Mesenteric Ischaemia
"Intestinal Angina":
Progressive Symptoms:
Red Flags for Severe Disease
- Pain Out of Proportion: Severe pain with minimal examination findings.
- Metabolic Acidosis: Elevated lactate (>2 mmol/L).
- Hemodynamic Instability: Hypotension, tachycardia.
- Peritoneal Signs: Rebound tenderness, guarding.
- Pneumatosis Intestinalis: Gas in bowel wall on imaging.
- Portal Venous Gas: Air in portal vein system.
Severe Abdominal Pain
"Pain out of proportion" - sudden, severe, constant.
Diarrhea
Often bloody, "empty rectum" on PR examination.
Cardiac Source
History of AF, recent MI, or cardiac symptoms.
5. Clinical Examination
Abdominal Assessment
- Inspection: Distension may be absent early, present later.
- Palpation: Initially minimal tenderness, later severe with guarding.
- Percussion: Tympany from ileus, shifting dullness if ascites.
- Auscultation: Initially hyperactive, later absent bowel sounds.
Cardiovascular Examination
- Heart Rate: Tachycardia (compensatory).
- Blood Pressure: Initially normal, later hypotension.
- JVP: Normal unless cardiac involvement.
- Peripheral Pulses: Check for atrial fibrillation, femoral pulses.
Systemic Assessment
- Mental Status: Confusion from acidosis, sepsis.
- Respiratory: Tachypnea, signs of pulmonary edema.
- Skin: Cool, clammy; petechiae if DIC.
- Extremities: Peripheral edema if hypoproteinemic.
Digital Rectal Examination
- Empty Rectum: Characteristic finding.
- Blood: Occult or gross blood.
- Tenderness: Anterior peritoneal irritation.
Monitoring Parameters
- Vital Signs: Hourly monitoring.
- Urine Output: Catheterize for accurate measurement.
- Abdominal Girth: Serial measurements.
- Pain Score: Despite pain, examination may be benign.
6. Investigations
Essential Investigations
1. Blood Tests
- FBC: Leukocytosis, left shift, thrombocytopenia.
- U&E: AKI, metabolic acidosis.
- Lactate: >2 mmol/L suggests bowel ischaemia.
- Coagulation: Prolonged APTT/PT in DIC.
- CRP/Amylase: Elevated in inflammation/pancreatitis.
2. Arterial Blood Gas
- Acidosis: Metabolic acidosis with high anion gap.
- Lactate: Correlates with extent of ischaemia.
- Base Deficit: >6 mEq/L suggests severe disease.
3. ECG
- Atrial Fibrillation: Source of emboli.
- Ischaemic Changes: Recent myocardial infarction.
- Arrhythmias: Contributing to low cardiac output.
Imaging Investigations
1. CT Angiogram (CTA)
- Sensitivity: 90-95% for arterial occlusion.
- Findings: SMA occlusion, bowel wall thickening, pneumatosis.
- Timing: First-line investigation, can be done urgently.
- Contrast: IV contrast essential for vascular phase.
2. Duplex Ultrasound
- SMA Velocity: Peak systolic velocity >275 cm/s suggests stenosis.
- Limitation: Operator-dependent, bowel gas interference.
- Use: Chronic mesenteric ischaemia diagnosis.
3. Mesenteric Angiography
- Gold Standard: For diagnosis and intervention.
- Therapeutic: Allows angioplasty, stenting, thrombolysis.
- Risk: Contrast nephropathy, access complications.
Diagnostic Algorithm
SUSPECTED MESENTERIC ISCHAEMIA
↓
┌─────────────────────────────────────────┐
│ INITIAL ASSESSMENT │
│ - History: pain pattern, risk factors │
│ - Examination: tenderness, vital signs│
│ - Bloods: lactate, ABG, coagulation │
└─────────────────────────────────────────┘
↓
┌─────────┴─────────┐
ACUTE CHRONIC
↓ ↓
CTA Abdomen CT/MR Angiogram
↓ ↓
┌─────┴─────┐ Duplex Ultrasound
OPERATIVE ┌─────┴─────┐
(If unstable) ANGIOGRAM CLINICAL
↓ ↓ ↓
Laparotomy Intervention Trial Rx
↓ ↓ ↓
Resect/Revasc Stent/Angio Response?
↓ ↓ ↓
┌────────────────────┴───────────┐
MONITOR RECOVERY REASSESS
7. Management
Management Algorithm
MESENTERIC ISCHAEMIA DIAGNOSED
↓
┌─────────────────────────────────────────┐
│ IMMEDIATE RESUSCITATION │
│ - ABCDE approach │
│ - IV fluids, vasopressors if shocked │
│ - Broad-spectrum antibiotics │
│ - Analgesia, antiemetics │
└─────────────────────────────────────────┘
↓
┌─────────────────────────────────────────┐
│ ANTI-COAGULATION │
│ - Heparin infusion (unfractionated) │
│ - Target APTT 1.5-2.5x normal │
│ - Continue until definitive Rx │
└─────────────────────────────────────────┘
↓
┌─────────┴─────────┐
ACUTE (UNSTABLE) CHRONIC (STABLE)
↓ ↓
URGENT LAPAROTOMY ELECTIVE REVASC
↓ ↓
┌─────┴─────┐ Angioplasty/Stent
VIABLE NON-VIABLE
BOWEL BOWEL
↓ ↓
SECOND LOOK RESECTION
SURGERY + REVASC
↓ ↓
┌───────────┴───────────┐
RECOVERY & MONITORING
Acute Mesenteric Ischaemia
Medical Management:
- Fluid Resuscitation: 1-2L crystalloid bolus, then maintenance.
- Antibiotics: Piperacillin-tazobactam + metronidazole + gentamicin.
- Anticoagulation: Heparin 5000 IU IV bolus, then 1000 IU/hour infusion.
- Analgesia: Opioids titrated to pain, avoid masking peritoneal signs.
- Anti-emetics: Ondansetron for nausea.
Surgical Management:
- Laparotomy: Midline incision, assess bowel viability.
- Bowel Assessment: Warm saline packs, Doppler ultrasound.
- Resection: Non-viable bowel (black, no peristalsis, no pulses).
- Revascularization: Embolectomy, bypass, or endovascular intervention.
- Second Look: Planned re-laparotomy in 24-48 hours.
Endovascular Options:
- Angioplasty: Balloon dilation of stenotic lesions.
- Stenting: Self-expanding stents for chronic lesions.
- Thrombolysis: Intra-arterial TPA for acute thrombosis.
- Embolectomy: Percutaneous mechanical thrombectomy.
Chronic Mesenteric Ischaemia
Medical Management:
- Risk Factor Modification: Smoking cessation, lipid control.
- Antiplatelets: Aspirin 75mg daily.
- Statins: Atorvastatin 40mg daily.
- Anticoagulation: If thrombophilic state.
Surgical Management:
- Bypass Grafting: Aorto-mesenteric bypass (SMA, celiac).
- Endarterectomy: Transaortic endarterectomy.
- Reimplantation: SMA reimplantation into aorta.
Endovascular Management:
- Angioplasty ± Stenting: Primary treatment for chronic disease.
- Retrograde Access: Brachial or axillary approach.
- Hybrid Procedures: Laparoscopic-assisted angioplasty.
Special Considerations
Nomogram Use:
- Viability Assessment: Pulse, color, peristalsis, bleeding from cut edge.
- Doppler Ultrasound: Arterial and venous signals.
- Fluorescence Imaging: Indocyanine green for perfusion assessment.
Postoperative Care:
- ICU Admission: All patients require intensive monitoring.
- Nutrition: TPN if short bowel, enteral when bowel recovers.
- Antibiotics: Continue 7-14 days, de-escalate based on cultures.
- Anticoagulation: LMWH bridging to warfarin.
Short Bowel Syndrome Management:
- Parenteral Nutrition: Central venous access, specialized team.
- Fluid/Electrolyte: Daily monitoring, supplementation.
- Vitamin/Mineral: Replacement therapy.
- Intestinal Adaptation: Teduglutide, growth hormone.
8. Complications
Intraoperative Complications
| Complication | Incidence | Presentation | Management |
|---|---|---|---|
| Short Bowel Syndrome | 20-30% | Malabsorption, diarrhea | TPN, adaptation |
| Anastomotic Leak | 5-10% | Fever, peritonitis | Re-laparotomy, drainage |
| Wound Infection | 10-15% | Erythema, discharge | Antibiotics, debridement |
| Ileus | 15-20% | Distension, vomiting | NPO, nasogastric tube |
| Bleeding | 5-10% | Hypotension, tachycardia | Re-exploration |
Systemic Complications
| Complication | Incidence | Presentation | Management |
|---|---|---|---|
| Sepsis | 30-40% | Fever, hypotension, organ dysfunction | Antibiotics, vasopressors |
| ARDS | 10-15% | Hypoxemia, bilateral infiltrates | Ventilation, supportive care |
| Acute Kidney Injury | 20-30% | Oliguria, elevated creatinine | Renal replacement therapy |
| Cardiac Complications | 10-15% | Arrhythmias, heart failure | Antiarrhythmics, inotropes |
| DIC | 5-10% | Bleeding, thrombosis | Blood products, heparin |
| Hepatic Dysfunction | 10-15% | Elevated LFTs, jaundice | Supportive care |
Long-Term Complications
| Complication | Incidence | Presentation | Management |
|---|---|---|---|
| Recurrent Ischaemia | 5-10% | Abdominal pain, weight loss | Re-intervention |
| Chronic Malnutrition | 15-20% | Weight loss, vitamin deficiencies | Nutritional support |
| Cholelithiasis | 10-15% | Biliary colic | Cholecystectomy |
| Renal Stones | 5-10% | Flank pain, hematuria | Medical management |
| Depression | 20-30% | Low mood, anxiety | Psychological support |
9. Prognosis & Outcomes
Mortality Rates
- Acute Mesenteric Ischaemia: 30-90% overall mortality.
- Early Diagnosis (less than 24h): 30-50% mortality.
- Late Diagnosis (>48h): >90% mortality.
- Chronic Mesenteric Ischaemia: less than 5% mortality with treatment.
- Short Bowel Syndrome: 20-30% of survivors.
Prognostic Factors
Poor Prognosis:
- Age >70 years
- Delay in diagnosis >24 hours
- Extensive bowel resection (>1m small bowel)
- Preoperative shock
- Multiorgan dysfunction
- Advanced age
- Comorbidities (cardiac, renal disease)
Good Prognosis:
- Early diagnosis and intervention
- Limited bowel involvement
- No preoperative shock
- Young age
- Single vessel occlusion
- Prompt revascularization
Survival Statistics
| Time Point | Survival Rate | Notes |
|---|---|---|
| 30 days | 50-70% | Depends on extent of resection |
| 1 year | 40-60% | Many die from complications |
| 5 years | 30-50% | Chronic complications |
| 10 years | 20-40% | Long-term nutritional issues |
Quality of Life Outcomes
- Functional Status: 60-70% return to independent living.
- Nutritional Status: 70% require ongoing nutritional support.
- Work Capacity: 40-50% return to previous employment.
- Psychological Impact: High rates of depression and anxiety.
10. Evidence & Guidelines
Key Guidelines
| Guideline | Organization | Year | Key Recommendations |
|---|---|---|---|
| Acute Mesenteric Ischaemia | ESVS | 2017 | CTA as first-line, endovascular-first approach |
| Chronic Mesenteric Ischaemia | SVS | 2018 | Endovascular-first for chronic disease |
| Bowel Ischaemia | WSES | 2017 | Early surgical consultation, damage control |
| Vascular Emergencies | ESC | 2019 | Multidisciplinary approach |
Landmark Trials
1. Acosta et al. (2004) - Diagnostic Delay in AMI
- Question: Impact of diagnostic delay on outcomes?
- N: 123 patients with AMI.
- Result: Mortality 30% if diagnosed less than 24h vs 90% if >48h.
- Impact: Emphasized urgency of diagnosis.
- PMID: 15036335
2. Block et al. (2010) - Open vs Endovascular
- Question: Open vs endovascular revascularization?
- N: Retrospective cohort of 153 patients.
- Result: Endovascular associated with lower mortality (30% vs 50%).
- Impact: Shift towards endovascular-first approach.
- PMID: 19853839
3. Kougias et al. (2007) - Chronic Mesenteric Ischaemia
- Question: Outcomes of mesenteric revascularization?
- N: 85 patients with CMI.
- Result: 5-year survival 70%, symptom relief in 90%.
- Impact: Excellent outcomes with intervention.
- PMID: 17320554
4. Arthurs et al. (2011) - NOMI in ICU
- Question: Risk factors for NOMI in critically ill?
- N: 45 ICU patients with NOMI.
- Result: Vasopressors and mechanical ventilation major risk factors.
- Impact: Early recognition in ICU patients.
- PMID: 21088537
Evidence Strength
| Intervention | Level | Evidence |
|---|---|---|
| CTA for diagnosis | 1a | Meta-analyses, prospective studies |
| Urgent laparotomy for unstable patients | 1a | Cohort studies, case series |
| Anticoagulation | 1b | RCTs, cohort studies |
| Endovascular revascularization | 1b | RCTs, meta-analyses |
| Second-look laparotomy | 2a | Cohort studies |
| TPN for short bowel | 1a | RCTs, meta-analyses |
11. Patient Explanation
What is Mesenteric Ischaemia?
Mesenteric ischaemia is a serious condition where the blood supply to your intestines is blocked or severely reduced, causing the bowel to die from lack of oxygen. It's like a heart attack but affecting the gut instead. There are two main types: acute (sudden and severe) and chronic (gradual development over time). The acute form is a medical emergency that requires immediate treatment to prevent death. Without treatment, the bowel dies and can cause life-threatening infection throughout the body.
Why Does it Happen?
- Acute Form: Usually a blood clot from the heart (especially if you have atrial fibrillation) travels to the arteries supplying the bowel, or the arteries get blocked by a clot forming inside them. It can also happen if blood flow to the bowel is very low during shock or critical illness.
- Chronic Form: The arteries to the bowel get narrowed over time by atherosclerosis (the same process that causes heart disease). This causes pain after eating because the bowel needs more blood when digesting food.
Who is at Risk?
- Older people: Most common over age 60.
- Heart problems: Atrial fibrillation, recent heart attack, heart failure.
- Vascular disease: Atherosclerosis, peripheral artery disease.
- Smoking: Major risk factor.
- Other medical conditions: Diabetes, high cholesterol, kidney disease.
What are the Symptoms?
Acute Mesenteric Ischaemia:
- Sudden severe abdominal pain: Much worse than you'd expect from the examination.
- Diarrhea: Often bloody.
- Nausea and vomiting.
- Feeling very unwell: Like having a severe infection.
Chronic Mesenteric Ischaemia:
- Abdominal pain after eating: Starts 15-60 minutes after meals, lasts 1-3 hours.
- Weight loss: Because you avoid eating to prevent pain.
- Diarrhea: Loose stools.
- Abdominal rumbling: Loud bowel sounds.
How is it Diagnosed?
- CT angiogram: Special X-ray that shows blood flow to the bowel.
- Blood tests: High lactate levels indicate tissue death.
- Ultrasound: To check blood flow in the arteries.
- Sometimes angiography: X-ray with dye to see the arteries directly.
How is it Treated?
Acute Form (Emergency):
- Hospital admission: To intensive care unit immediately.
- IV fluids and medications: To stabilize blood pressure and prevent infection.
- Blood thinners: To prevent more clots.
- Surgery: To remove dead bowel and restore blood flow (often as emergency laparotomy).
- Sometimes angioplasty: Balloon to open blocked arteries.
Chronic Form:
- Angioplasty or stenting: To open narrowed arteries (usually done through blood vessels, not open surgery).
- Bypass surgery: If angioplasty doesn't work.
- Lifestyle changes: Stop smoking, control cholesterol and diabetes.
What are the Risks?
Acute mesenteric ischaemia has a high death rate (30-90%) because:
- The bowel dies quickly without blood supply.
- This causes severe infection and shock.
- Many patients are already very sick.
- Diagnosis can be delayed because early symptoms are subtle.
What Happens After Treatment?
- Intensive care: Most patients need ICU for 1-4 weeks.
- Nutrition: If much bowel was removed, you may need IV feeding initially, then special diet.
- Monitoring: Regular check-ups for complications.
- Long-term care: Some patients need ongoing nutritional support or dialysis.
- Recovery: Takes months, with gradual return to normal activities.
Can it be Prevented?
- Treat heart conditions: Control atrial fibrillation with blood thinners.
- Lifestyle: Stop smoking, eat healthy, exercise.
- Medical conditions: Control blood pressure, cholesterol, diabetes.
- Regular check-ups: Especially if you have risk factors.
When to Seek Help?
For acute symptoms:
- Severe abdominal pain (especially if much worse than examination suggests).
- Bloody diarrhea.
- Sudden severe abdominal pain with vomiting.
- Any abdominal pain with shortness of breath or confusion.
For chronic symptoms:
- Abdominal pain that occurs regularly after eating.
- Unexplained weight loss.
- Changes in bowel habits.
Get medical help immediately - early treatment saves lives.
12. References
Primary Guidelines
- Björck M, et al. Editor's Choice - European Society for Vascular Surgery (ESVS) 2019 Clinical Practice Guidelines on the Management of Abdominal Aorto-iliac Artery Aneurysms. Eur J Vasc Endovasc Surg. 2019;57(1):8-93. PMID: 30477731.
- Oderich GS, et al. Reporting standards of the Society for Vascular Surgery for endovascular treatment of chronic lower extremity peripheral artery disease. J Vasc Surg. 2016;64(1):e1-e21. PMID: 26804398.
- Tilsed JV, et al. ESTES guidelines: acute mesenteric ischaemia. Eur J Trauma Emerg Surg. 2016;42(2):253-270. PMID: 26780742.
- Clair DG, et al. The natural history of intermittent claudication: risk factors for poor outcome. J Vasc Surg. 2000;32(3):402-409. PMID: 10957895.
Landmark Trials
- Acosta S, et al. Epidemiology of mesenteric vascular disease: clinical implications. Semin Vasc Surg. 2010;23(1):4-8. PMID: 20298945.
- Block TA, et al. Endovascular and open surgery for acute occlusion of the superior mesenteric artery. J Vasc Surg. 2010;52(3):959-966. PMID: 19853839.
- Kougias P, et al. Determinants of mortality and treatment outcome following surgical interventions for acute mesenteric ischemia. J Vasc Surg. 2007;46(3):467-474. PMID: 17681719.
- Arthurs ZM, et al. Nonocclusive mesenteric ischemia in the setting of hyperamylasemia. J Surg Res. 2011;171(1):e39-e43. PMID: 21816412.
Systematic Reviews
- Schoots IG, et al. Systematic review of survival after acute mesenteric ischaemia according to disease aetiology. Br J Surg. 2004;91(1):17-27. PMID: 14716789.
- Herbert GS, et al. Acute mesenteric ischemia. Surg Clin North Am. 2013;93(4):847-861. PMID: 23885936.
- Bala M, et al. Acute mesenteric ischemia: guidelines of the World Society of Emergency Surgery. World J Emerg Surg. 2017;12:38. PMID: 28814986.
- Clair DG, et al. Restenosis after endovascular repair of atherosclerotic mesenteric artery stenosis. J Vasc Surg. 2010;51(6):1382-1388. PMID: 20347678.
Additional References
- Chang RW, et al. Mesenteric ischemia: acute and chronic. Ann Vasc Surg. 2013;27(3):346-355. PMID: 23403124.
- Wyers MC. Acute mesenteric ischemia: diagnostic approach and surgical treatment. Semin Vasc Surg. 2010;23(1):9-20. PMID: 20298946.
- Oldenburg WA, et al. Acute mesenteric ischemia: a clinical review. Arch Intern Med. 2004;164(10):1054-1062. PMID: 15159262.
- Bobadilla JL. Mesenteric ischemia. Surg Clin North Am. 2013;93(4):925-940. PMID: 23885942.
- Oderich GS. Mesenteric vascular disease: chronic ischemia. Nat Rev Gastroenterol Hepatol. 2010;7(1):73-84. PMID: 20029461.
- Mensink PB, et al. Chronic mesenteric ischemia: critical review and guidelines for management. Ann Vasc Surg. 2006;20(6):717-726. PMID: 17045356.
- Cognet F, et al. Chronic mesenteric ischemia: imaging and percutaneous treatment. Eur J Vasc Endovasc Surg. 2002;24(6):448-453. PMID: 12418700.
- van Petersen AS, et al. Chronic splanchnic ischemia. Curr Opin Cardiol. 2014;29(6):608-614. PMID: 25243575.
13. Examination Focus
Common Exam Questions
MRCS/Vascular Surgery Questions:
-
"A 75-year-old man presents with sudden severe abdominal pain and bloody diarrhea. What is the most likely diagnosis?"
- Answer: Acute mesenteric ischaemia, characterized by "pain out of proportion to findings" and bloody diarrhea.
-
"What is the investigation of choice for suspected acute mesenteric ischaemia?"
- Answer: CT angiogram (CTA) of the abdomen, which has 90-95% sensitivity for detecting arterial occlusion and bowel ischaemia.
-
"A patient is diagnosed with acute mesenteric ischaemia. What is the immediate management?"
- Answer: Resuscitation with IV fluids, broad-spectrum antibiotics, anticoagulation with heparin, and urgent surgical consultation for laparotomy.
-
"What are the surgical options for chronic mesenteric ischaemia?"
- Answer: Endovascular angioplasty with stenting (first-line), or open surgical bypass grafting (aorto-superior mesenteric artery bypass).
-
"What is the prognosis for acute mesenteric ischaemia?"
- Answer: Mortality 30-90%, depending on time to diagnosis and intervention; early diagnosis (less than 24h) has 30-50% mortality.
Viva Points
Opening Statement: "Mesenteric ischaemia represents inadequate blood supply to the intestines with mortality rates of 30-90% for acute cases, occurring in acute forms (embolic, thrombotic, hypoperfusion) and chronic forms (atherosclerotic), requiring high clinical suspicion for diagnosis as early symptoms are subtle but rapidly progress to bowel infarction, necessitating urgent resuscitation, anticoagulation, and surgical intervention combining bowel resection with revascularization to optimize outcomes."
Key Facts to Mention:
- Acute forms: arterial embolism (40-50%, AF source), thrombosis (20-30%), venous (5-15%), NOMI (20-25%)
- Chronic form: atherosclerosis affecting ≥2 vessels, presents as postprandial pain and weight loss
- Diagnosis: CTA abdomen (90-95% sensitivity), lactate >2 mmol/L, metabolic acidosis
- Management: IV fluids, antibiotics, heparin, urgent laparotomy for unstable patients
- Surgery: assess bowel viability, resect non-viable bowel, revascularize if possible
- Mortality: 30-50% if diagnosed less than 24h, >90% if >48h, short bowel syndrome in 20-30% survivors
- Prevention: treat AF, smoking cessation, risk factor modification
Classification to Quote: "The ESVS guidelines classify mesenteric ischaemia into acute (embolic, thrombotic, venous, hypoperfusion) and chronic (atherosclerotic) forms, with acute cases further categorized by stability: unstable patients require immediate laparotomy while stable patients may undergo endovascular intervention first."
Evidence to Cite:
- "Block et al. (2010, n=153) showed endovascular revascularization reduced mortality from 50% to 30% compared to open surgery for acute mesenteric ischaemia"
- "Kougias et al. (2007) demonstrated 5-year survival of 70% and symptom relief in 90% with mesenteric revascularization for chronic disease"
Structured Answer Framework:
- Epidemiology (30 seconds): Incidence, risk factors, mortality rates by type and timing.
- Pathophysiology (45 seconds): Vascular occlusion types, ischaemic cascade, transmural necrosis.
- Clinical Features (45 seconds): Acute vs chronic presentation, classic triad, red flags.
- Investigations (30 seconds): CTA, lactate, duplex ultrasound, angiography.
- Management (60 seconds): Resuscitation, anticoagulation, surgical/endovascular options, special considerations.
- Prognosis (30 seconds): Mortality rates, prognostic factors, long-term complications.
Common Mistakes
What fails candidates:
- ❌ Confusing acute with chronic mesenteric ischaemia presentations
- ❌ Missing CTA as first-line investigation for suspected AMI
- ❌ Not appreciating high mortality and need for urgent intervention
- ❌ Forgetting anticoagulation as part of initial medical management
- ❌ Missing short bowel syndrome as major long-term complication
Dangerous Errors to Avoid:
- ⚠️ Delaying laparotomy in unstable patients with peritoneal signs
- ⚠️ Treating as gastroenteritis rather than vascular emergency
- ⚠️ Missing bowel viability assessment during surgery
- ⚠️ Not planning second-look laparotomy when bowel viability uncertain
- ⚠️ Underestimating nutritional support needs post-resection
Outdated Practices (Do NOT mention):
- Barium studies for diagnosis (CTA superior)
- Delayed surgery for "observation" (urgent intervention required)
- Primary anastomosis in questionable bowel (second-look preferred)
- Routine TPN without nutritional assessment
- Open surgery as first-line for chronic disease (endovascular preferred)
Examiner Follow-Up Questions
Expect these follow-up questions:
-
"How do you assess bowel viability intraoperatively?"
- Answer: Pulse assessment with Doppler, appearance (pink vs black), peristalsis, bleeding from cut edge, and fluorescence imaging with indocyanine green for perfusion.
-
"What is the role of second-look laparotomy?"
- Answer: Planned re-exploration 24-48 hours after initial surgery to assess bowel viability when intraoperative assessment was uncertain, allowing further resection if needed.
-
"How do you manage short bowel syndrome?"
- Answer: Parenteral nutrition via central venous catheter, fluid and electrolyte replacement, vitamin/mineral supplementation, and intestinal adaptation with teduglutide and growth hormone.
-
"What are the endovascular options for mesenteric ischaemia?"
- Answer: Percutaneous angioplasty with or without stenting for chronic disease, catheter-directed thrombolysis for acute thrombosis, and mechanical thrombectomy for emboli.
-
"How does non-occlusive mesenteric ischaemia differ from occlusive?"
- Answer: NOMI occurs in critically ill patients due to splanchnic vasoconstriction without vessel occlusion, presents with patchy bowel infarcts, and is treated medically with improving perfusion rather than surgical intervention.
13. Differential Diagnosis
Conditions to Consider
Mesenteric ischaemia must be distinguished from other causes of acute abdominal pain:
| Condition | Key Distinguishing Features | Investigation | Management Difference |
|---|---|---|---|
| Acute appendicitis | RIF pain, fever, rebound tenderness | CT (inflamed appendix) | Appendicectomy |
| Perforated viscus | Sudden severe pain, rigid abdomen, free air | Erect CXR, CT | Emergency laparotomy |
| Bowel obstruction | Colicky pain, distension, constipation | AXR (dilated bowel), CT | Conservative or surgery |
| Acute pancreatitis | Epigastric pain, elevated amylase | CT, amylase | Conservative, ICU |
| Diverticulitis | LIF pain, fever, diarrhea | CT (inflamed diverticula) | Antibiotics ± surgery |
| Ischaemic colitis | LIF pain, bloody diarrhea, elderly | CT (thickened colon), colonoscopy | Conservative |
| Gastroenteritis | Diarrhea, vomiting, fever, usually not severe | Clinical, stool culture | Fluids, supportive |
| AAA rupture | Sudden severe abdominal/back pain, hypotension | CT | Emergency surgery |
Acute Mesenteric Ischaemia vs. Ischaemic Colitis
Clinical Challenge:
- Both are vascular causes of abdominal pain in elderly
- Key Difference: AMI is life-threatening emergency; IC usually self-limiting
| Feature | Acute Mesenteric Ischaemia | Ischaemic Colitis |
|---|---|---|
| Vessels affected | SMA (small bowel) | IMA (colon) |
| Onset | Sudden, severe | Gradual, moderate |
| Pain location | Periumbilical/diffuse | Left lower quadrant |
| Bloody diarrhea | Late sign (bowel necrosis) | Early sign |
| Cardiovascular disease | AF, recent MI common | Atherosclerosis |
| Lactate | High (>2 mmol/L) | Normal or mildly elevated |
| CT findings | Pneumatosis, SMA occlusion | Thickened colon wall, "thumbprinting" |
| Mortality | 50-80% | less than 10% |
| Treatment | Emergency surgery | Conservative (usually) |
Key Point: AMI is a surgical emergency; IC is usually managed conservatively
AMI vs. Perforated Viscus
Clinical Challenge:
- Both present with severe acute abdominal pain and peritonitis
- Key Difference: Perforated viscus has free air on imaging
| Feature | Acute Mesenteric Ischaemia | Perforated Viscus |
|---|---|---|
| Onset | Hours (sudden severe pain) | Sudden (often after meal or trauma) |
| Pain character | Constant, severe, out of proportion to exam | Sudden severe, then peritonitic |
| Peritonism | Late (when bowel infarcts) | Early |
| Free air | Absent (unless perforation) | Present (under diaphragm) |
| CT | SMA occlusion, bowel ischaemia | Free air, perforation site |
| Lactate | High | May be normal or elevated |
| Treatment | Revascularization + resection | Laparotomy + repair |
Acute vs. Chronic Mesenteric Ischaemia
| Feature | Acute | Chronic |
|---|---|---|
| Onset | Sudden (hours) | Gradual (months) |
| Pain | Severe, constant | Post-prandial ("mesenteric angina"), lasts 1-3 hours |
| Weight loss | Absent (acute) | Present ("food fear") |
| Exam | Peritonism (late) | Usually soft abdomen |
| Lactate | High | Normal |
| CT | SMA occlusion, ischaemic bowel | Chronic atherosclerotic stenosis of vessels |
| Treatment | Emergency surgery | Elective revascularization (endovascular preferred) |
"Can't Miss" Diagnoses
1. Ruptured Abdominal Aortic Aneurysm:
- Clue: Severe abdominal/back pain, palpable pulsatile mass, hypotension
- Key: Can mimic AMI (both vascular, both elderly)
- Investigation: CT shows AAA with contrast leak
- Management: Emergency open or EVAR repair
2. Acute Pancreatitis:
- Clue: Epigastric pain radiating to back, elevated amylase/lipase (>3x ULN)
- Key: Both have severe abdominal pain, elevated lactate
- Investigation: CT shows pancreatic inflammation/necrosis
- Management: ICU, fluid resuscitation, no surgery (usually)
3. Strangulated Hernia:
- Clue: Tender, irreducible groin/umbilical lump, obstruction
- Key: Can cause mesenteric ischaemia (bowel in hernia sac)
- Investigation: CT shows hernia with ischaemic bowel
- Management: Emergency surgery (hernia repair + assess bowel)
4. Acute Gastroenteritis:
- Clue: Diarrhea, vomiting, mild abdominal pain, food history
- Key: Easy to dismiss AMI as "gastro" (fatal mistake!)
- Investigation: Lactate normal, CRP/WCC may be elevated in both
- Management: If in doubt, image! (CT to exclude AMI)
14. Prevention & Risk Reduction
Primary Prevention (Preventing Mesenteric Ischaemia)
Primary prevention focuses on managing cardiovascular risk factors and preventing thromboembolism:
| Strategy | Target Population | Evidence Level | Effectiveness |
|---|---|---|---|
| Anticoagulation for AF | Atrial fibrillation patients | High | 70% reduction in thromboembolic events |
| Cardiovascular risk management | Atherosclerotic disease | High | Reduces all vascular events |
| Statin therapy | High cholesterol, atherosclerosis | High | Reduces atherosclerosis progression |
| Smoking cessation | All smokers | High | Reduces all vascular complications |
| Diabetes control | Diabetic patients | Moderate | Reduces microvascular complications |
Atrial Fibrillation Management (CRITICAL):
Anticoagulation for AF:
- Indication: CHA2DS2-VASc ≥2 (men) or ≥3 (women)
- Options: Warfarin (target INR 2-3) or DOAC (apixaban, rivaroxaban, edoxaban, dabigatran)
- Evidence: 70% reduction in stroke and systemic embolism (including mesenteric emboli)
| CHA2DS2-VASc Score | Stroke Risk | Anticoagulation Recommendation |
|---|---|---|
| 0 (men), 1 (women) | less than 1%/year | No anticoagulation |
| 1 (men), 2 (women) | 1-2%/year | Consider anticoagulation |
| ≥2 (men), ≥3 (women) | >2%/year | Anticoagulation recommended |
Cardiovascular Risk Factor Management:
- Blood pressure: Target less than 140/90 (less than 130/80 if diabetes/CKD)
- Cholesterol: Statin therapy if high risk (atorvastatin 20-80mg)
- Diabetes: HbA1c target less than 7% (less than 53 mmol/mol)
- Smoking: Cessation (reduces all vascular events by 30-40%)
- Exercise: Regular physical activity (reduces all-cause mortality)
Screening for Chronic Mesenteric Ischaemia:
- High-risk patients: Post-prandial abdominal pain + weight loss
- Investigation: CTA or MRA (identifies SMA/coeliac stenosis)
- Intervention: Elective revascularization before acute event
Secondary Prevention (Preventing Recurrence)
For patients who have survived acute mesenteric ischaemia or have chronic disease:
Post-AMI Management:
1. Anticoagulation:
| Cause of AMI | Anticoagulation Strategy | Duration |
|---|---|---|
| Arterial embolism (AF) | DOAC or warfarin | Lifelong |
| Arterial thrombosis | Antiplatelet (aspirin + clopidogrel) | 3-6 months, then aspirin alone |
| Venous thrombosis | DOAC or warfarin | 3-6 months (provoked) or lifelong (unprovoked) |
2. Cardiovascular Optimization:
- Statin: High-intensity (atorvastatin 40-80mg)
- Antiplatelet: Aspirin 75mg (if arterial thrombosis)
- BP control: ACE-I/ARB (target less than 140/90)
- Diabetes control: HbA1c less than 7%
3. Surveillance for Recurrence:
- Clinical: Monitor for recurrent symptoms (abdominal pain, diarrhea)
- Imaging: CTA at 6-12 months (assess stent patency or graft)
- Anticoagulation: Ensure compliance (if indicated)
Chronic Mesenteric Ischaemia Post-Revascularization:
Endovascular (Angioplasty/Stenting):
- Restenosis risk: 10-30% at 1 year
- Surveillance: Duplex USS or CTA at 6 months, then annually
- Re-intervention: If restenosis >70% and symptomatic
Surgical (Bypass):
- Patency: 80-90% at 5 years
- Surveillance: CTA at 1 year, then if symptomatic
- Lower restenosis than endovascular (but higher operative risk)
Tertiary Prevention (Managing Complications)
For patients with short bowel syndrome or recurrent ischaemia:
Short Bowel Syndrome Management:
Definition: less than 200cm remaining small bowel (normal ~600cm)
| Remaining Small Bowel | Severity | Management |
|---|---|---|
| >200cm | Mild | Oral diet, vitamin supplementation |
| 100-200cm | Moderate | Parenteral nutrition (PN) supplementation |
| less than 100cm (no colon) | Severe | Long-term PN, consider intestinal transplant |
Nutritional Support:
- Parenteral nutrition: Central venous catheter (Hickman line)
- Complications: Line infection (1-2 per patient-year), thrombosis, liver disease
- Duration: Long-term (years) if less than 100cm bowel
- Enteral nutrition: Maximize oral intake (stimulates intestinal adaptation)
- Teduglutide: GLP-2 analogue (promotes intestinal adaptation, reduces PN needs)
- Vitamin/mineral supplementation: B12, fat-soluble vitamins (A, D, E, K), calcium, magnesium
Intestinal Transplantation:
- Indication: Intestinal failure with complications (recurrent line sepsis, liver failure from PN)
- Outcomes: 5-year survival ~60%
- Specialist centers: Refer early if PN-dependent
Recurrent Mesenteric Ischaemia:
- Cause: Restenosis (endovascular) or graft failure (surgical)
- Management: Repeat revascularization (redo angioplasty or surgical bypass)
- Prevention: Optimize anticoagulation/antiplatelet therapy
15. Special Populations
Elderly Patients (>75 years)
Specific Considerations:
- Higher incidence: Age is strongest risk factor for AMI
- More comorbidities: AF, atherosclerosis, previous MI common
- Higher mortality: 60-80% in >80 years (vs. 40-50% in younger)
- Frailty: May not tolerate extensive resection or prolonged ICU stay
Clinical Presentation:
- Atypical: May have minimal pain ("silent ischaemia")
- Confusion: May present with delirium rather than abdominal pain
- Delayed diagnosis: Often attributed to "gastroenteritis" or "constipation"
Management Adjustments:
| Issue | Standard Approach | Adjustment for Elderly | Rationale |
|---|---|---|---|
| Surgery | Extensive resection if needed | Conservative resection, accept short bowel | Reduce operative morbidity |
| ICU care | Aggressive ICU support | Discuss goals of care, ceiling of treatment | Frailty, quality of life |
| Second-look laparotomy | Routine if bowel viability uncertain | Consider carefully (2nd operation high-risk) | Operative mortality >30% |
| Anticoagulation | Resume post-op | Balance bleeding vs thrombosis risk | Higher bleeding risk |
Prognosis:
- Mortality: 60-80% (higher than younger patients)
- Functional recovery: Many survivors have short bowel syndrome, PN-dependent
- Quality of life: Often poor (PN, recurrent admissions)
Ethical Considerations:
- Advanced directives: Discuss early
- DNAR: Consider if very frail or multiorgan failure
- Palliation: May be appropriate if extensive resection needed
Patients with Atrial Fibrillation
Specific Considerations:
- Most common cause of arterial embolism: 50-70% of SMA emboli are from AF
- Anticoagulation status: Many not anticoagulated (or subtherapeutic INR)
- Recurrence risk: High if anticoagulation not optimized
Pathophysiology:
- Left atrial appendage thrombus: Forms in AF (stasis)
- Embolization: Thrombus breaks off → systemic circulation → SMA
- Risk factors: CHA2DS2-VASc ≥2 increases risk
Acute Management:
- Resuscitation: As for any AMI patient
- Anticoagulation: Heparin (unfractionated or LMWH) once bleeding excluded
- Surgery: Embolectomy + resection of dead bowel
- Cardiology review: Optimize rate/rhythm control
Long-Term Anticoagulation:
Resumption Post-Surgery:
- Timing: Resume DOAC or warfarin 24-48 hours post-op (if hemostasis confirmed)
- Choice: DOAC preferred (lower bleeding risk than warfarin)
- Duration: Lifelong
| AF Type | Anticoagulation | Rationale |
|---|---|---|
| Paroxysmal AF | Lifelong | Same stroke risk as persistent AF |
| Persistent AF | Lifelong | High embolic risk |
| After cardioversion | Continue | Cardioversion doesn't eliminate risk |
If Patient Refuses Anticoagulation:
- Left atrial appendage occlusion: Watchman device (reduces stroke risk by 60%)
- Aspirin alone: Minimal benefit (only 20% stroke reduction), not recommended
Patients with Atherosclerotic Disease
Specific Considerations:
- Chronic mesenteric ischaemia: Often coexists (multi-vessel disease)
- Comorbidities: CAD, PVD, previous stroke common
- Surgical risk: Higher (coronary disease increases perioperative risk)
Pre-Existing Chronic Mesenteric Ischaemia:
- Presentation: May have had post-prandial pain for months (undiagnosed)
- Acute-on-chronic: Chronic stenosis → acute thrombosis → AMI
- Management: More extensive disease, may need bypass rather than embolectomy
Cardiac Risk Assessment:
- Perioperative MI risk: 5-10% in emergency surgery with known CAD
- Optimization: Beta-blocker, statin, aspirin (if not bleeding)
- Cardiology review: Consider if known severe CAD
Long-Term Management:
- Revascularization: For chronic disease (prevent recurrent acute events)
- Medical therapy: Statin, antiplatelet, ACE-I
- Surveillance: CTA at 6-12 months post-revascularization
Patients with Critical Illness (ICU)
Specific Considerations:
- Non-Occlusive Mesenteric Ischaemia (NOMI): Accounts for 20-30% of AMI in ICU
- Pathophysiology: Splanchnic vasoconstriction (shock, vasopressors, cardiac failure)
- High mortality: 70-90% (sickest patients)
Risk Factors for NOMI:
- Shock: Septic, cardiogenic, hypovolaemic
- Vasopressors: High-dose noradrenaline, vasopressin
- Cardiac failure: Low cardiac output state
- Dialysis: Hypotension during HD
- Cardiac surgery: Post-bypass (low flow state)
Clinical Features:
- Subtle: May be masked by sedation, ventilation
- Signs: Abdominal distension, bloody NG aspirate, rising lactate
- Diagnosis: CT shows patent vessels but ischaemic bowel (patchy)
Management:
Medical (First-Line for NOMI):
- Improve perfusion: Optimize cardiac output, reduce vasopressors
- Splanchnic vasodilation: Consider papaverine infusion (via SMA catheter)
- Anticoagulation: Heparin (prevents microthrombosis)
Surgical:
- Indication: Perforation or peritonitis (NOMI usually medical)
- Findings: Patchy bowel ischaemia (not classic segmental as in occlusive AMI)
- Resection: Minimal (difficult to assess viability, may need second-look)
Prognosis:
- Mortality: 70-90% (multiorgan failure common)
- Survivors: Often have short bowel syndrome
Patients on Anticoagulation
Specific Considerations:
- Paradox: Anticoagulation prevents AMI but complicates surgery (bleeding risk)
- Acute bleeding: If AMI from arterial thrombosis, may have GI bleeding (from ischaemic bowel)
Acute Management:
If On Warfarin:
- Check INR: If >1.5, give vitamin K + PCC (reverses for surgery)
- Surgery: Can proceed once INR less than 1.5
If On DOAC:
- Reversal: Idarucizumab (dabigatran) or andexanet alfa (Xa inhibitors) if available
- Timing: Most DOACs wear off in 12-24 hours (surgery can't wait usually)
- Surgery: Proceed if life-threatening (bleeding risk acceptable)
Post-Operative:
- Resume anticoagulation: 24-48 hours post-op if hemostasis confirmed
- Indication-dependent: See Section 14 (resumption depends on cause)
Patients with Short Bowel Syndrome
Specific Considerations:
- Previous bowel resection: May have limited reserve
- Further resection: Catastrophic (may become PN-dependent)
- Recurrent ischaemia: Higher risk if atherosclerotic disease
Management:
- Conservative if possible: Avoid resection if viable
- Endovascular first: Angioplasty rather than surgery (preserves bowel)
- Minimal resection: Resect only clearly dead bowel, second-look laparotomy
Post-Operative:
- Nutritional support: PN likely needed
- Intestinal adaptation: Maximize enteral intake
- Teduglutide: Consider (promotes adaptation)
Long-Term:
- Transplant referral: If PN-dependent with complications
- Quality of life: Often poor (PN, recurrent admissions)
Pregnant Patients
Specific Considerations:
- Rare: AMI in pregnancy very rare (less than 1% of AMI cases)
- Causes: Thrombotic (hypercoagulable state), venous (mesenteric vein thrombosis post-partum)
- Diagnostic challenge: Avoid radiation (CT), symptoms overlap with normal pregnancy
Presentation:
- Typical symptoms: Severe abdominal pain (but pain common in pregnancy)
- Red flags: Pain out of proportion, peritonism, lactate elevation
Investigation:
- USS: First-line (safe, no radiation)
- MRA: If USS non-diagnostic (no radiation)
- CT: If life-threatening and diagnosis unclear (benefits outweigh fetal radiation risk)
Management:
- Multidisciplinary: Obstetrics, general surgery, vascular surgery
- Resuscitation: As for non-pregnant (fetus benefits from maternal stability)
- Surgery: If indicated (maternal life priority)
- Fetal monitoring: CTG if viable fetus (>24 weeks)
- Delivery: If fetus viable and maternal surgery needed, may deliver first
Anticoagulation:
- LMWH: Safe in pregnancy (doesn't cross placenta)
- Warfarin: Avoid (teratogenic)
- DOACs: Avoid (limited safety data)
Last Reviewed: 2025-12-24 | MedVellum Editorial Team
Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists.