ARTERIAL EMBOLISM:

Typical triad: abdominal pain (out of proportion to clinical signs), bowel emptying and source of embolism e.g. AF.
Note - triad is only present in approximately 80% of cases, there may be a window of opportunity when pain is decreased.

ARTERIAL THROMBOSIS:

Abdominal pain, history of atherosclerotic disease. High index of suspicion needed. Dehydration, low cardiac output and hypercoagulable states may be precipitating factors. Patient may have had chronic mesenteric ischaemia.

VENOUS THROMBOSIS:

Non-specific presentation – always consider as a differential diagnosis of the acute abdomen.

NON-OCCLUSIVE (LOW FLOW STATES):

Usually secondary to severe systemic illness: most commonly hypoperfusion secondary to severe cardiac failure or acute coronary syndrome, aortic dissection, sepsis, massive burn injury, post renal replacement therapy.

• Full history, examination and routine bloods
• D-dimer is useful to exclude mesenteric ischaemia if negative, but low specificity if positive
• Lactate measurement it is not recommended to diagnose or rule out acute occlusive mesenteric ischaemia; it is a useful marker of general deterioration and hypoperfusion no matter the cause
• Early CT scan of abdomen (contrast enhanced in both arterial and portal venous phase) is essential; renal impairment is not a contraindication given that mesenteric ischaemia is life-threatening

• Admit under the care of General Surgeon on call (Consultant of the Week during the day, Consultant of the Day out-of-hours)
• Alert Consultant as soon as suspicion of mesenteric ischaemia is raised
• Start supportive treatment immediately – oxygen, fluid resuscitation, analgesia
• Give IV antibiotics if signs of perforation or sepsis from bacterial translocation
• Consider IV heparin infusion; anticoagulation is the mainstay of treatment for acute mesenteric venous thrombosis
• Consider level 2 care if significant physiological derangement present
• Keep patient nil-by-mouth
• Consultant-to-Consultant referral to Vascular Surgery is essential as soon as clinical or radiological working diagnosis is made
• Consultant Vascular Surgeon may discuss patient with Consultant in Interventional Radiology if endovascular approach is judged to be an option (depending on availability)

• Ad hoc MDT decision is desirable but should not delay a definitive procedure
• Key decision is whether to proceed to immediate laparotomy, use endovascular approach first or rely on medical treatment
• Laparotomy is mandatory if peritonism or other signs of intestinal infarction present (unless palliative approach indicated)
• Risk stratification using P-POSSUM and NELA scoring may aid in pre-operative decision making
• Laparoscopy is not recommended to assess extent of ischaemia
• There should be a low threshold for second-look laparotomy (or laparotomy after endovascular procedure)
• Consultant General Surgeon is responsible for co-ordination of care and will remain in charge
• Patient care may be transferred to Consultant Vascular Surgeon if revascularisation is successful

•  Isolated colon ischaemia is managed by General/Colorectal Surgery – vascular reconstruction is not usually feasible
• Chronic mesenteric ischaemia is not covered in this protocol – patients are usually managed as outpatients

For further information, please refer to the following:

• ESVS guidelines
• BMJ best practice

Risk calculators:

• P-POSSUM
• NELA