This is a basic article for medical students and other non-radiologists
Intestinal ischaemia refers to vascular compromise of the bowel which in the acute setting has a very high mortality if not treated expediently. Diagnosis is often straight forward provided appropriate imaging is obtained. The disease can be arbitrarily classified into broad groups according to the time of onset, or the portion of bowel involved or the underlying cause.
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Reference article
This is a summary article; read more in our article on intestinal ischaemia.
Summary
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epidemiology
- conditions that predispose to ischaemia
- tends to be more likely in older populations
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presentation
- variable, but often with pain and distension
- acute symptom onset might point towards arterial occlusion
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pathophysiology
- anything that results in reduced blood flow and metabolites to the bowel
- general hypotension, hypoxaemia or sepsis
- arterial occlusion (SMA, IMA)
- bowel obstruction
- venous outflow obstruction (SMV)
- anything that results in reduced blood flow and metabolites to the bowel
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investigation
- CT angiography it the test of choice
- CTA requires rapid contrast infusion and therefore, an appropriate cannula
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treatment
- first line treatment is often resuscitation
- depends on the cause of ischaemia and its severity
- necrotic bowel needs to be resected
Role of imaging
- look for evidence of ischaemia
- look at the blood supply - arterial and venous
- assess of any complication, e.g. perforation
- look for any other cause of symptoms
Radiographic features
CT has replaced catheter angiography as the gold standard for assessment for intestinal ischaemia. It allows assessment of the whole abdomen in multiple vascular phases, e.g. arterial, portal venous, delayed. It also has the added advantage of being able to diagnose alternative causes of acute abdominal pain.
CT
Imaging features can vary depending on the time course and aetiology. A number of features are common to most advanced acute cases and result from the bowel wall necrosis and perforation:
- pneumatosis intestinalis: gas in intestinal wall
- pneumatosis portalis: gas in the portal vein or in mesenteric vein
- pneumoperitoneum: perforation of the bowel
- variable amounts of free fluid
The bowel wall is not always thickened - in fact, it may be thinned where there is complete arterial occlusion or bowel obstruction.