Superior mesenteric artery (SMA) dissection is rare. We herein report about a case of SMA dissection which required resection of a large amount of the small intestine and the colon. A 59-year-old male with vague lower abdominal pain and diarrhea was admitted to our hospital. An erect abdominal X-ray showed niveau. His condition deteriorated and on the fifth day from the onset, an enhanced computed tomography (CT) revealed the SMA was dissected along 3 cm of its length from its origin, and the blood supply to the small intestine was shuttered in association with false lumen formation. Finally, the patient was necessitated an emergency surgery. A grayish ischemic small intestine and ascending colon were seen along with a moderate amount of ascites. The ischemic part of the intestine was resected. Pathological findings revealed coagulation necrosis with inflammatory cell infiltration, blood congestion, and hemorrhage. This coagulation necrosis was compatible with hemorrhagic necrosis due to intestinal ischemia. In conclusion, enhanced CT was available for detecting SMA dissection. If a patient with acute abdomen of unknown origin is encountered, SMA dissection should be ruled out, because ischemic intestine due to SMA occlusion is time-dependent and life-threatening. Furthermore, in the case of extensive bowel resection, the management of short bowel syndrome is thought to be essential
