Colonic blood supply Colonic blood supply. Pink - supply from superior mesenteric artery (SMA) and its branches: middle colic, right colic, ileocolic arteries. Blue - supply from inferior mesenteric artery (IMA) and its branches: left colic, sigmoid, superior rectal artery. 7 is for so-called Cannon-Böhm point (the border between the areas of SMA and IMA supplies),thumb 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<unk>  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<unk>  due to this dual blood supply. Development of<unk>  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%,<unk>  will develop. The arteries feeding the colon are very sensitive to vasoconstrictors; presumably this is an evolutionary adaptation to shunt blood away from the bowel and to the heart and brain in times of stress. As a result, during periods of low blood pressure, the arteries feeding the colon clamp down vigorously; a similar process can result from vasoconstricting drugs such as ergotamine, cocaine, or vasopressors. This vasoconstriction can result in non-occlusive<unk> . Pathologic findings A range of pathologic findings are seen in<unk> , corresponding to the spectrum of clinical severity. In its mildest form, mucosal and submucosal hemorrhage and edema are seen, possibly with mild necrosis or ulceration. With more severe<unk> , a pathologic picture resembling inflammatory bowel disease (i.e. chronic ulcerations, crypt abscesses and pseudopolyps) may be seen. In the most severe cases, transmural infarction with resulting perforation may be seen; after recovery, the muscularis propria may be replaced by fibrous tissue, resulting in a stricture. Following restoration of normal blood flow, reperfusion injury may also contribute to the damage to the colon.
Ischemic colitis
Ulcerative colitis
Diversion colitis
Chemical colitis
Collagenous colitis
Cytomegalovirus colitis
Microscopic colitis
Diverticulitis