Small bowel ischaemia may be a life-threatening condition, arising from any one of numerous causes of disturbance of the normal blood flow through the small bowel wall.
Pathology
Aetiology
It can be divided into acute and chronic forms, with the main underlying aetiologies (each discussed separately) being:
-
acute
- occlusive mesenteric ischaemia
- superior mesenteric artery occlusion (two-thirds of cases)
- superior mesenteric vein occlusion (5-10% of cases)
- non-occlusive mesenteric ischaemia (e.g. shock bowel) 2
- systemic hypotension (e.g. cardiogenic, septic, or haemorrhagic shock)
- blunt abdominal trauma
- medication-induced (e.g. vasoconstriction from digitalis, amphetamines, cocaine)
- small vessel involvement
- chemotherapy-induced enteropathy (possibly ischaemic in nature)
- acute radiation enteritis
- vasculitides (rare)
-
small bowel obstruction
- increasing bowel wall diameter increases bowel wall tension, which increases the resistance to incoming blood flow
- occlusive mesenteric ischaemia
-
chronic
- atherosclerotic stenosis of the superior mesenteric artery (e.g. mesenteric angina)
- chronic radiation enteritis