ISCHEMIC COLITIS

Ischemic colitis represents the most common form of gastrointestinal i schemia. The presumed etiologies are numerous; however, it typically d evelops ''spontaneously,'' in the absence of major vasculature occlusi on, and in the presence of viable intestine elsewhere. It is most usef ully classified into gangrenous and nongangrenous forms, the latter of which may be subdivided into transient and chronic types. Ischemic co litis may develop in people who are otherwise healthy, although a vari ety of clinical settings, such as shock, predispose to its occurrence. It usually presents as an acute abdominal illness with bloody diarrhe a. Diagnosis is confirmed by colonoscopy. Therapy and outcome are depe ndent on the severity of disease. Nongangrenous colonic ischemia usual ly requires only medical management and is associated with a good prog nosis. The chronic subtype may lead to the sequelae of persistent segm ental colitis or colonic strictures, occasionally requiring surgery. U rgent operative intervention and a high morbidity and mortality are th e hallmarks of gangrenous colonic ischemia. Special considerations mus t be given to those patients in whom ischemic colitis develops in the context of colon carcinoma or obstructing colon lesions, after abdomin al aortic surgery, and following cardiopulmonary bypass. This review w ill discuss the clinical spectrum of ischemic colitis.