Small bowel ischemia 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
Etiology
It can be divided into acute and chronic forms, with the main underlying etiologies (each discussed separately) being:
-
acute
- occlusive mesenteric ischemia
- superior mesenteric artery occlusion (two-thirds of cases)
- superior mesenteric vein occlusion (5-10% of cases)
- non-occlusive mesenteric ischemia (e.g. shock bowel) 2
- systemic hypotension (e.g. cardiogenic, septic, or hemorrhagic shock)
- blunt abdominal trauma
- medication-induced (e.g. vasoconstriction from digitalis, amphetamines, cocaine)
- small vessel involvement
- chemotherapy-induced enteropathy (possibly ischemic 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 ischemia
-
chronic
- atherosclerotic stenosis of the superior mesenteric artery (e.g. mesenteric angina)
- chronic radiation enteritis