Acute colonic ischemia is the most common form of intestinal ischemia. Nonocclusive ischemic colitis contributes to some of these disorders. Heart disease, such as congestive heart failure, myocardial infarction, arrhythmias, aortic valve disease, and atherosclerotic cardiovascular disease, account for many of its risk factors. The majority of cases are associated with severe congestive heart failure with low cardiac output, or disease states resulting in dehydration, or the splanchnic vasoconstrictive effect of some medications. Reactive splanchnic vasoconstriction is responsible for nonocclusive ischemic colitis. Ischemic colitis induced by a cleansing enema has been reported once before. The authors present a case of coronary artery disease complicated by colonic ischemia following glycerin enema in preparation for coronary bypass surgery. Reactive inferior mesenteric artery spasm in response to the enema was noted in this case, rather than diffuse mesenteric artery spasm in response to low cardiac output state and vasoconstrictive drugs.