Snapshot A 65-year-old gentleman presents with acute onset severe abdominal pain. The pain is described as "diffuse" without localization and constant. The patient states that he has had nausea and vomitting with this episode. Physical examination shows absent bowel sounds, mild abdominal distention, and pain that is disproportionate to the exam findings. Introduction Clinical definition medical condition where the small intestine is injured secondary to any process that reduces intestinal blood flow acute mesenteric ischemia characterized by acute onset of severe abdominal pain and is associated with high risk of mortality chronic mesenteric ischemia gradual decrease of blood flow typically associated with atherosclerosis characterized by postprandial abdominal pain with unintentional weight loss, food aversion, and vomiting Epidemiology demographics most commonly affects people > 60 years of age risk factors atrial fibrillation heart failure chronic kidney failure hypercoagulable states previous myocardial infarction Pathogenesis can be due to a variety of processes acute mesenteric ischemia is most commonly caused by an embolism in the main mesenteric artery chronic mesenteric ischemia is most commonly caused by atherosclerosis arterial occlusion embolism secondary to atrial fibrillation, myocardial infarction, or valvular disease thrombosis secondary to artherosclerosis non-occlusive arterial disease splanchnic vasoconstriction hypoperfusion due to hypotension venous thrombosis Presentation Acute mesenteric ischemia symptoms sudden onset of severe abdominal pain nausea diarrhea vomiting gastrointestinal bleeding physical exam fever tachycardia abdominal pain out of proportion to physical findings peritoneal signs if bowel infarction Chronic mesenteric ischemia symptoms post-prandial abdominal pain that resolves (e.g., "intestinal angina") nausea food aversion vomiting gastrointestinal bleeding physical exam weight loss abdominal bruit Imaging Mesenteric angiography gold standard for arterial occlusive disease allows for differentiation of the different etiologies and direct infusion of vasodilators in the setting of nonocclusive ischemia Computed tomography (CT) with angiography best initial imaging will elucidate other causes of abdominal pain findings may include mesenteric edema, bowel dilatation, bowel wall thickening, intramural gas, and mesenteric stranding Abdominal radiograph can rule out other causes of abdominal pain images will often appear normal Studies Laboratory studies leukocytosis elevated lactic acid Differential Ischemic colitis differentiating factors will demonstrate pathology of the large bowel on imaging Perforated viscus differentiating factors visualization of gas on abdominal radiograph Treatment Therapy is dependent on the etiology and can be pharmacological or surgical Non-occlusive mesenteric ischemia IV fluid resuscitation nasogastric tube decompression anti-coagulation regimen (as needed) vasodilator (e.g. papaverine) Occlusive mesenteric ischemia surgical revascularization via angioplasty thrombolytic therapy Emergency laparotomy indicated if evidence of bowel infarction/necrosis or peritonitis may require bowel resection Complications Sepsis Death Bowel necrosis Perforation