Necrosis may occur but is usually limited to the mucosa and submucosa, only occasionally causing full-thickness necrosis necessitating surgery. Ischemic colitis occurs mainly in older people (> 60) and is thought to be caused by small-vessel atherosclerosis Atherosclerosis Atherosclerosis is characterized by patchy intimal plaques (atheromas) that encroach on the lumen of medium-sized and large arteries. The plaques contain lipids, inflammatory cells, smooth muscle... read more 
. It can also be a complication of abdominal aortic aneurysm Abdominal Aortic Aneurysms (AAA) Abdominal aortic diameter ≥ 3 cm typically constitutes an abdominal aortic aneurysm. The cause is multifactorial, but atherosclerosis is often involved. Most aneurysms grow slowly (~10%/year)... read more 
repair.
Symptoms and Signs of Ischemic Colitis
Symptoms of ischemic colitis are milder and of slower onset than those of acute mesenteric ischemia Symptoms and Signs Acute mesenteric ischemia is interruption of intestinal blood flow by embolism, thrombosis, or a low-flow state. It leads to mediator release, inflammation, and ultimately infarction. Abdominal... read more 
and consist of left lower quadrant pain followed by rectal bleeding. The pathophysiology and treatment of the two conditions are quite different.
Diagnosis of Ischemic Colitis
CT or colonoscopy
Diagnosis of ischemic colitis is made by CT or colonoscopy.
Angiography or magnetic resonance angiography is not indicated.
Treatment of Ischemic Colitis
IV fluids, bowel rest, and antibiotics
Rarely surgery
Treatment of ischemic colitis is supportive with IV fluids, bowel rest, and antibiotics.
The underlying cause of the low-flow state (eg, control of cardiac arrhythmia) is treated if relevant.
Surgery is rarely required, unless ischemic colitis is a complication of a vascular procedure or there is full-thickness necrosis. About 5% of patients have a recurrence.
Occasionally, strictures develop at the site of the ischemia several weeks later, necessitating surgical resection.
