Findings: Axial images through the abdomen demonstrate small bowel dilatation as well as bowel wall thickening. In addition, there is pneumatosis intestinalis as well as portal venous gas.
Diagnosis: Small bowel ischemia/infarction.
Discussion: Ischemic disease of the bowel can be divided into four categories: Acute mesenteric ischemia, chronic mesenteric ischemia, focal segmental ischemia and colonic ischemia.
Acute mesenteric ischemia has several causes; however, SMA obstruction secondary to an embolus is the most common cause. Patients at greatest risk are those with a history of atrial fibrillation, ischemic heart disease, hypovolemia as well as post myocardial infarction. Acute mesenteric ischemia has a mortality rate of between 75 and 90%. Pneumatosis can be seen in other disorders such as peptic ulcer disease, steroid use, COPD as well as inflammatory bowel disease. Angiography is the key to treating acute mesenteric ischemia, because it helps differentiate between SMA embolism, SMA thrombosis (atherosclerosis), SMV thrombosis (15%) and nonocclusive ischemia (30%). CT findings include bowel wall thickening, dilated bowel loops, intramural gas, as well as mesenteric and portal venous gas. Thrombus formation within the SMA and SMV can also be demonstrated.
Chronic mesenteric ischemia is a consequence of atherosclerotic disease. This entity is known as abdominal angina and a two-thirds reduction in blood flow in two of the three major visceral vessels is needed.
Colonic ischemia is usually caused by low flow states or small vessel disease. There is a wide range of clinical findings from mild abdominal pain to gangrene of the colon. Angiography is not indicated and the diagnosis is made with colonoscopy or barium enema (except in cases of suspected gangrene or perforation).
References:
Eisenberg R. Gastrointestinal Radiology. Lippincott Company;
1993:876-880 and 898-908.
Gore, et al. Textbook of Gastrointestinal Radiology. Philadelphia;
1994:967-982 and 2694-2705.
Submitted by: