Mondo Description Superior mesenteric artery syndrome (SMAS) is a digestive condition that occurs when the duodenum (the first part of the small intestine) is compressed between two arteries (the aorta and the superior mesenteric artery). This compression causes partial or complete blockage of the duodenum. Symptoms vary based on severity, but can be severely debilitating. Symptoms may include abdominal pain, fullness, nausea, vomiting, and/or weight loss. SMAS typically is due toloss of the mesenteric fat pad (fatty tissue that surrounds the superior mesenteric artery). The most common cause is significant weight loss caused by medical disorders, psychological disorders, or surgery. In younger patients, it most commonly occurs after corrective spinal surgery for scoliosis. Delays in diagnosis may result in significant complications. Depending on the cause and severity, treatment options may include addressing the underlying cause, dietary changes (small feedings or a liquid diet), and/or surgery. Symptoms may not resolve completely after treatment.