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Superior mesenteric artery syndrome

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Other Names:
Vascular compression of the duodenum; Wilkie syndrome; Cast syndrome; Vascular compression of the duodenum; Wilkie syndrome; Cast syndrome; Arteriomesenteric duodenal compression syndrome See More
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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.[1] Symptoms vary based on severity, but can be severely debilitating.[2] Symptoms may include abdominal pain, fullness, nausea, vomiting, and/or weight loss.[3] SMAS typically is due to loss 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.[3] Delays in diagnosis may result in significant complications.[3] 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.[1][3][4] Symptoms may not resolve completely after treatment.[3]
Last updated: 6/14/2018
The signs and symptoms of superior mesenteric artery syndrome vary but may include:[3][5][1]
  • Feeling full quickly when eating
  • Bloating after meals
  • Burping (belching)
  • Nausea and vomiting of partially digested food or bile-like liquid
  • Small bowel obstruction
  • Weight loss
  • Mid-abdominal "crampy" pain that may be relieved by the prone or knee-chest position or by lying on the left side
Last updated: 5/16/2016
SMAS typically is due to loss of the mesenteric fat pad (fatty tissue that surrounds the superior mesenteric artery).[3] The superior mesenteric artery forms an angle with the abdominal aorta (due in part to the mesenteric fat pad), and part of the duodenum sits within this angled space. Anything that sharply narrows the angle between the aorta and superior mesenteric artery can cause compression of the duodenum, resulting in SMAS.[1][3] 

The most common cause of loss of the mesenteric fat pad is significant weight loss caused by medical disorders, psychological disorders, or surgery. Anatomic abnormalities can also contribute to SMAS. In younger patients, it most commonly occurs after corrective spinal surgery for scoliosis.[3]

There are some reports of familial cases of SMAS, and one report of affected identical twins. This suggests there may be a genetic predisposition to SMAS in some people.[3][6]

There are also several reported cases of SMAS associated with celiac axis compression syndrome.[3]
Last updated: 7/6/2017
SMAS is not considered an inherited condition. Most cases occur sporadically in people with no family history of SMAS.[1] 

There are some reports of familial cases of SMAS, and one report of affected identical twins. This suggests there may be a genetic predisposition to SMAS in some people.[6][3]
Last updated: 7/6/2017
Superior mesenteric artery syndrome (SMAS) may be suspected based on signs and symptoms, although symptoms can be nonspecific. The diagnosis is often made after other causes of symptoms have been ruled out.[3]

Tests that may be needed to evaluate a person with symptoms of SMAS include abdominal X-rays, upper GI series, ultrasound, arteriography, and computed tomography (CT scan).[1][3]

Diagnosis is often delayed and this may result in significant complications, including gastric pneumatosis (gas within the walls of the GI tract), accumulation of gas in the portal vein, formation of an obstructing duodenal bezoar (solid mass of indigestible material), or fatalities due to electrolyte abnormalities or gastric perforation.[3]
Last updated: 7/6/2017
Treatment for superior mesenteric artery syndrome typically focuses on addressing the underlying cause of the condition.[1] For example, symptoms often improve after lost weight is restored or a body cast is removed.[4] Nasogastric decompression (a tube passed through the nose into the stomach) and proper positioning after eating (such as lying in the left side or standing or sitting with a knee-to-chest position) may be recommended to alleviate symptoms.[1]

In severe cases, intravenous (IV) nutritional support and/or a feeding tube may be needed to provide enough calories. Affected people can usually then be started on oral liquids, followed by slow and gradual introduction of small and frequent soft meals as tolerated. Then, regular solid foods may be introduced. Metoclopramide treatment to avoid vomiting may be beneficial for some people.[1]

Surgery may be needed if other treatment strategies do not work. However, other treatment options should usually be tried for at least 4-6 weeks before considering surgery.[1]

Surgery options are:[3]
  • Strong’s procedure: Where the duodenum is re-positioned to the right of the superior mesenteric artery
  • Gastrojejunostomy: Where the jejune (the part of the intestines that continues with the duodenum) is joined directly to the stomach
  • Duodenojejunostomy with or without division or resection of the fourth part of the duodenum.
Last updated: 10/4/2016
Superior mesenteric artery syndrome can be severely debilitating and may require long term management, medications, costly parenteral nutrition (intravenous feeding) and rigorous follow-up.[2] The long-term outlook (prognosis) can depend on whether the condition is diagnosed and treated in a timely manner. The prognosis may be excellent if it is diagnosed quickly and appropriate therapy is given.[1] However, the condition may go unrecognized until a person experiences symptoms for a long time.[2] In the past, deaths have been reported due to complications including progressive dehydration, hypokalemia (low potassium), and oliguria (producing too little urine). Most deaths have been reported in people in whom the diagnosis was delayed or missed.[1]

Other complications that may arise in people with SMAS include:[1]
  • Other electrolyte imbalances
  • Malnutrition
  • Hypotension
  • Peptic ulcer disease
  • Aspiration pneumonia
Last updated: 2/20/2017

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Superior mesenteric artery syndrome. Click on the link to view a sample search on this topic.

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  1. Karrer FM. Superior Mesenteric Artery Syndrome. Medscape Reference. January 6, 2017; http://emedicine.medscape.com/article/932220-overview.
  2. FJ Bohanon, O Nunez Lopez, BM Graham, LW Griffin, and RS Radhakrishnan. A Case Series of Laparoscopic Duodenojejunostomy for the Treatment of Pediatric Superior Mesenteric Artery Syndrome. Int J Surg Res. April, 2016; https://www.ncbi.nlm.nih.gov/pubmed/27747293.
  3. Scovell S & Hamdan A. Superior Mesenteric Artery Syndrome. UpToDate. Waltham, MA: UpToDate; March 6, 2017; http://www.uptodate.com/contents/superior-mesenteric-artery-syndrome.
  4. Superior Mesenteric Artery (SMA) Syndrome. International Foundation for Functional Gastrointestinal Disorders. September 2014; http://www.iffgd.org/site/gi-disorders/other/sma-syndrome.
  5. Gebhart T. Superior Mesenteric Artery Syndrome. Gastroenterol Nursing. May-June 2015; 38(3):189-93. http://www.ncbi.nlm.nih.gov/pubmed/26035775.
  6. Ortiz C, Cleveland RH, Blickman JG, Jaramillo D, Kim SH. Familial superior mesenteric artery syndrome. Pediatric Radiology. October, 1990; 20(8):588-589. https://link.springer.com/article/10.1007/BF02129061.