Superior Mesenteric Artery Syndrome in an Adolescent Presenting with Acute Massive Gastric Obstruction.

Superior mesenteric artery syndrome (SMAS) is an uncommon cause of proximal intestinal obstruction caused by compression of the third portion of the duodenum between the SMA and the abdominal aorta. We report the case of a 17-year-old boy with a 2-year history of recurrent nausea, vomiting, epigastric pain, early satiety, postprandial fullness, and progressive abdominal distension, followed by recent clinical deterioration. Despite repeated non-diagnostic investigations and empirical dietary and pharmacological treatment, symptoms persisted. Contrast-enhanced computed tomography established the diagnosis by demonstrating a markedly reduced aortomesenteric angle of approximately 10° and an aortomesenteric distance of 5.5 mm, associated with severe gastric and proximal duodenal dilatation. The patient was treated conservatively with nasogastric decompression and nutritional support. Nasogastric tube placement resulted in marked gastric decompression, with substantial improvement in abdominal distension, epigastric discomfort, early satiety, and vomiting, allowing surgical intervention to be deferred during the acute phase. Follow-up showed no further acute obstructive deterioration; however, the absence of meaningful weight gain over the subsequent six months indicated persistence of the chronic nutritional component of SMAS and the need for continued dietary rehabilitation and close monitoring. This case highlights the diagnostic difficulty of SMAS in adolescents with chronic, treatment-refractory upper gastrointestinal symptoms and emphasizes that resolution of acute obstruction should not be equated with definitive correction of the underlying disease process. Early recognition, conservative stabilization, nutritional optimization, and longitudinal reassessment are essential to prevent delayed diagnosis and guide timely escalation to surgery when conservative treatment is insufficient.