RADIOLOGY: VASCULAR: Case# 41: SMA THROMBUS AND PNEUMATOSIS. History 1: The patient is a 28-year-old male who presents to our ER with hypertension, heme-positive NG aspirate, and diffuse gaseous distention of the entire bowel with pneumatosis of the stomach. History 2: The patient is a 28 year old white male S/P small bowel resection for ischemic bowel on 5/16/95. Patient now returns with recurrent abdominal pain and fever. Exam 1:A large amount of portal venous gas is present. The remainder of the liver is unremarkable. The spleen is mildly enlarged. Pneumatosis affects the stomach, duodenum, jejunum, and ileum. It is worse within the jejunum and proximal ileum. The distal ileum and colon demonstrate no evidence of pneumatosis. There is also thickening of the small bowel wall with marked enhancement. A small amount of free fluid is present within the gutters and now within the pelvis. The patient has free intraperitoneal air. The superior mesenteric artery demonstrates thrombus within its proximal lumen. Contrast does fill the mid and distal portions of the SMA. The celiac axis appears widely patent. The infrarenal aorta has an irregular lumen, consistent with atherosclerotic disease. The infrahepatic IVC is obliterated. Multiple collaterals within the retroperitoneum and body wall are present and empty into the azygous and hemiazygous system. The azygous is dilated above the diaphragm. Exam 2:A small amount of air is seen in the liver which is most likely in the portal venous system. This is much less than on prior exam. The remainder of the liver is otherwise unremarkable. There are multiple loops of dilated fluid-filled small bowel with long segments of pneumatosis. The colon is edematous but no definite pneumatosis is seen. The duodenum does not appear to be affected. There is no definite abscess formation or free intraperitoneal air. A small amount of intraperitoneal fluid is present. There is again noted to be thrombosis of the superior mesenteric artery beginning at the origin and extending distally, more extensive than on previous exam. The IVC is obliterated, essentially unchanged since previous exam. Multiple collaterals within the retroperitoneum and body wall are again noted with dilatation of the azygous and hemiazygous systems. Streaky patchy areas of decreased perfusion are noted bilaterally in the kidneys. Occlusion of the superior mesenteric artery may be caused by thrombosis, embolus, trauma, adhesions, or vasculitis, leading to bowel ischemia and acute abdomen. Evidence of bowel ischemia may be seen on plain films as well as CT. Typical findings include ileus, thickening of the bowel wall, and irregular thickened mucosal folds. In addition, CT may show linear or punctate collections of gas in the bowel wall and gas in the mesenteric and portal veins. Thrombus within the mesenteric vein may be seen on contrast-enhanced images.