Superior mesenteric artery syndrome: an approach to the diagnosis and management of upper gastrointestinal obstruction of unclear etiology.

The differential diagnosis of upper intestinal obstruction includes mechanical obstruction, obstruction secondary to systemic disease, and idiopathic intestinal pseudo-obstruction. The causes of these are extensive; however, the majority of cases involve a mechanical etiology. Superior mesenteric artery syndrome (SMAS) is a rare and controversial form of mechanical obstruction with just over 300 well-defined cases described in literature. The diagnosis is often difficult to establish, even after surgery. In addition, this syndrome sometimes may be managed conservatively, leaving a definitive diagnosis unproven. A case of SMAS and a description of the syndrome is presented. The patient was managed conservatively and recovered without difficulty. One of the most difficult diseases to differentiate from SMAS is megaduodenum (intestinal pseudo-obstruction localized to the duodenum). Both entities present as obstruction with an unclear etiology. A reasonable approach to the diagnosis and management of upper intestinal obstruction (including figures, tables, and an algorithm), with emphasis on the above two diseases, is discussed.