Educational draft — clinical review pending​

What it means

SMAS occurs when the duodenum, the first part of the small intestine, is compressed between the superior mesenteric artery and aorta. This narrows or obstructs the digestive passage, rather than blocking the artery. Food and liquids may have difficulty passing. Loss of cushioning fatty tissue, including after substantial weight loss, can contribute; other settings include certain injuries or operations.

Sources: Johns Hopkins — MALS and SMAS program; Cleveland Clinic — SMA syndrome

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Common symptoms

Pain after meals, nausea, vomiting, early fullness, bloating and unintended weight loss may occur. Ongoing vomiting and difficulty eating can affect hydration/nutrition and cause dangerous electrolyte disturbances or malnutrition.

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How it is evaluated

Symptoms, weight changes, history and imaging are considered together. CT examines the anatomy; an upper gastrointestinal contrast study may show passage through the digestive tract. The question is whether anatomy produces obstruction that fits the clinical picture, not a number taken from a scan in isolation.

Sources: Cleveland Clinic — SMA syndrome; Sinagra and colleagues — SMAS study

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Care discussions

Treatment often starts with clinician-guided nutrition and attention to overall condition. Nutrition route/hospital care depend on circumstances. Persistent symptoms or obstruction may prompt surgery discussions. Duodenojejunostomy bypasses the compressed section. Surgery cannot guarantee every digestive symptom resolves; other gastrointestinal problems, including motility disorders, need assessment/follow-up.

Sources: Sinagra and colleagues — SMAS study; Johns Hopkins — MALS and SMAS program; Long-term surgical outcomes study

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Questions to ask

What shows obstruction? How will nutrition/hydration be supported safely? How will we judge progress? When consider surgery? Could another digestive condition contribute?

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Urgent symptoms

Seek urgent care for sudden sharp abdominal pain, vomiting blood, or inability to pass stool with vomiting. Contact a clinician promptly if unable to keep food or liquids down.

Source: MedlinePlus — Abdominal pain

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Sources checked September 30, 2026. Educational draft; clinical review pending.