amounts of rectal bleeding. The sensitivity of findings among 73 patients were: abdominal pain (78%) lower gastrointestinal tract bleeding (62%) diarrhea (38%) Fever higher than (34%) Physical examination abdominal pain (77%) abdominal tenderness (21%) Causes Ischemic colitis is often classified according to the underlying cause. Non-occlusive ischemia develops because of low blood pressure or constriction of the vessels feeding the colon; occlusive ischemia indicates that a blood clot or other blockage has cut off blood flow to the colon. Non-occlusive ischemia In hemodynamically unstable patients (i.e. shock) the mesenteric perfusion may be compromised. This condition is commonly asymptomatic, and usually only apparent through a systemic inflammatory response. Occlusive ischemia Mostly the result of a thromboembolism. Commonly the embolism is caused by atrial fibrillation, valvular disease, myocardial infarction, or cardiomyopathy. In addition, ischemic colitis is a well-recognized complication of abdominal aortic aneurysm repair, when the origin of the inferior mesenteric artery is covered by the aortic graft. In a 1991 review concerning 2137 patients the accidental inferior mesenteric artery ligation was the most common cause (74%) of ischemic colitis. Thus, patients without adequate collateralization are at risk for ischemia of the descending and sigmoid colon. Bloody diarrhea and leukocytosis in the postoperative period are essentially diagnostic of ischemic colitis. The complication can be prevented through careful selection of subjects that may require replanting inferior mesenteric artery (IMA) and completing the pre surgical procedure information with an instrumental evaluation during surgical treatment. Pathophysiology Colonic blood supply The colon receives blood from both the superior and inferior mesenteric arteries. The blood supply from these two major arteries overlaps, with abundant collateral circulation via the marginal artery of the colon. However, there are weak points, or "watershed" areas, at the borders of the territory supplied by each of these arteries, such as the splenic flexure and the rectosigmoid junction. These watershed areas are most vulnerable to ischemia when blood flow decreases, as they have the fewest vascular collaterals. The rectum receives blood from both the inferior mesenteric artery and the internal iliac artery; the rectum is rarely involved by colonic ischemia due to this dual blood supply. Development of ischemia Under ordinary conditions, the colon receives between 10% and 35% of the total cardiac output. If blood flow to the colon drops by more than about 50%, ischemia will develop. The arteries feeding the colon are very sensitive to vasoconstrictors; presumably this is an