BACKGROUND
A 30-year-old white man presents to the emergency department with intermittent episodic discomfort in the upper abdomen that has lasted more than 10 years. Although the episodes are frequently severe and last several hours to 2 days, they resolve spontaneously. The patient reports no exacerbating factors, and weeks and months can pass between episodes. He is completely asymptomatic between these events. Nausea, occasional bloating, and nonbilious emesis are associated with the episodes. The patient's bowel pattern is normal, without hematochezia, and he has had no weight loss or fevers. Results of multiple evaluations in the past, including upper endoscopy and upper gastrointestinal contrast studies, have been normal.

The review of systems is otherwise unremarkable. The patient works in an office and does not smoke or drink. He takes no medications and has no allergies. The patient underwent laparoscopic cholecystectomy in the past and once had a hip fracture from a fall.

On examination, the patient is markedly uncomfortable. Abdominal palpation reveals tenderness in the epigastrium with guarding but no rebound. No masses or organomegaly are detected. Bowel sounds are normal. Findings on rectal examination are normal, with no masses and heme-negative brown stool. The patient's vital signs, remaining physical findings, and laboratory values are normal.

What is the diagnosis?

Hint
Abdominal CT is helpful in establishing the diagnosis.

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Answer
Superior mesenteric artery syndrome: The abdominal CT scan shows marked dilatation of the proximal duodenum. At the level of the superior mesenteric artery (SMA), the third part of the duodenum is narrowed. The duodenum is compressed by a sharp aortomesenteric angle as it passes between the SMA and aorta, resulting in SMA syndrome. The distal duodenum appears normal in caliber. Initially recognized by Von Rokitansky in 1861, SMA syndrome is an uncommon cause of chronic, intermittent, or acute complete or partial duodenal obstruction. Often a diagnostic dilemma, this entity is a diagnosis of exclusion.

The patient was referred for elective surgical evaluation to discuss his candidacy for laparoscopic jejunostomy bypass