Ischemic Small Bowel
(Gastroenterology 2000;118:951-53 & 954-68)
DEFINITION:
Ischemic injury of the intestine resulting from deprivation of oxygen and nutrients necessary for cellular integrity
EPIDEMIOLOGY:
Responsible for about 0.1% of admissions to tertiary care centers (or 1 per 1,000)
ETIOLOGIES:
SMA embolism (50%): From left atrium or left ventricle
Risk factors: older age, atrial fibrillation, valvular disease, myxoma, CHF/low-flow states, MI, arrhythmias, angiography
SMA thrombosis (15%): usually at the site of atherosclerosis which many times is at the origin of artery
Risk factors: older age, low-flow states (hypotension, arrhythmia, MI, CHF), atherosclerosis, hypercoagulable state, vasculitis
Mesenteric venous thrombosis (5-10%): of which 95% occur in the SMV
Risk factors:
Hypercoagulable states (personal/family history, protein C & S deficiency, antiphospholipid, sickle cell)
Abdominal inflammation/infection (peritonitis, appendicitis, pancreatitis, diverticulitis, abscess, Crohn’s, vasculitis, trauma)
Portal HTN/Cirrhosis, malignant obstruction
Non-occlusive mesenteric ischemia (20%): Low cardiac output ± high doses of vasoconstrictors
Risk factors:
Low-flow states (CHF, MI, pulmonary edema, arrhythmia, shock, sepsis, pancreatitis, burns, hemorrhage)
Vasospasm (cocaine, digoxin)
Focal segmental ischemia of the small bowel (5%): vascular occlusion to small segments of the small bowel
Risk factors: vasculitis, atheromatous emboli, strangulated hernias, radiation therapy
DDX: perforated viscus, small bowel obstruction, cecal volvulus, incarcerated hernia, dissecting aortic aneurysm, pancreatitis/cholecystitisRelated posts:
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