Acute Mesenteric Ischemia

The patient's white blood cell (WBC) count was 17,000/μL (no left shift). Viral gastroenteritis was diagnosed by the ED physicians. Very mild right-sided weakness and occasional "pins and needles" sensations in the right leg were residual effects of a stroke the patient had suffered 9 years earlier. He also had hypercholesteremia, with a high low-density lipoprotein level and a low high-density lipoprotein level (36 mg/dL). The patient was taking gemfibrozil, fexofenadine, and aspirin. In the ED, intravenous narcotics were needed to control the severe abdominal pain. Because of the extreme pain and the history of cerebral infarction, bowel ischemia was considered in the differential diagnosis. A contrastenhanced CT scan of the abdomen showed a linear band with lack of contrast enhancement to the proximal portion of the superior mesenteric artery (Figure); this raised the suspicion of dissection. A CT angiogram confirmed the diagnosis of superior mesenteric artery dissection with concomitant celiac artery dissection. The workup included assessment of protein C and protein S activity and lupus anticoagulant, anticardiolipin antibody, and factor V Leiden levels. No abnormality was identified except for an elevated C-reactive protein level of 1.07 mg/dL (normal, 0.026 to 0.5 mg/dL). The erythrocyte sedimentation rate was 10 mm/h (normal, 0 to 10 mm/h); the glycated hemoglobin level was normal. Intravenous heparin, pravastatin, and dextran were given; the pain resolved in 48 hours. Warfarin was prescribed, a therapeutic international normalized ratio was attained, and the patient was discharged on the ninth hospital day. He was lost to follow-up. CLINICAL FEATURES Acute mesenteric ischemia— which is more common than chronic ischemia—often remains undiagnosed until the bowel dies and must be resected. The arterial tree is involved more frequently than the venous system. Inadequate blood supply from the superior mesenteric artery causes ischemia in the small intestine and the right half of the colon. Reduced blood flow from the inferior mesenteric artery leads to ischemia of the distal transverse colon and proximal rectum. Possible sequelae range from transient alterations in bowel function to hemorrhage and death. About 75% to 90% of affected patients present with acute abdominal pain that is usually out of proportion to the early physical findings (Table 1). Typically, the pain is of sudden onset and followed by rapid and often forceful bowel evacuation. Occasionally, unexplained abdominal distention or bleeding may be the only symptom. Distention, though uncommon, may signify the initial stage of intestinal infarction.