How to confirm a suspected diagnosis of ischemic colitis ?
Abdominal plain films may demonstrate “thumbprinting” along the affected segment of colonic wall, often the splenic flexure, secondary to subepithelial edema and hemorrhage.
If ischemic colitis is suspected and there are no signs of peritoneal irritation, the patient should undergo colonoscopy for diagnostic confirmation. Any region of the colon may be involved, but the key feature is segmental distribution, classically at watershed areas between the SMA and IMA. The rectosigmoid (20%), descending colon (20%), splenic flexure (11%), and all three in combination (14%) are affected most commonly. A flexible sigmoidoscopy may be nondiagnostic in those with more proximal disease. The rectum is almost always spared because of its dual blood supply from the IMA and internal iliac artery branches.
Barium enema is less sensitive than colonoscopy but may reveal thumbprinting. Angiography is not indicated as predisposing nonocclusive vascular factors are often not demonstrated after ischemic injury has occurred.