The following information may help to address your question:
What is the superior mesenteric artery?
The superior mesenteric artery is a large artery in the abdominal cavity that provides blood to the small intestine
, cecum, and colon. The small intestine is the portion of the digestive system most responsible for absorption of nutrients from food into the bloodstream. Click here
to view a diagram of the superior mesenteric artery from the MERCK Manual Web site.
The superior mesenteric artery makes its way between two layers of the mesentery (membranous tissue which carries blood vessels and lymph glands and attaches organs to the abdominal wall) and crosses over the first part of the small intestine, called the duodenum. The duodenum is where partly digested foods from the stomach mix with bile from the gall bladder and digestive juices from the pancreas.
Last updated: 7/26/2012
What is superior mesenteric artery syndrome?
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.
Signs and symptoms may include abdominal fullness; bloating after meals; nausea and vomiting; and abdominal cramping that may be helped by lying in certain positions. The condition is more common after severe and rapid weight loss or after prolonged bedrest, rapid growth, previous abdominal surgery, lordosis
, use of body casts, and loss of tone in abdominal muscles. It may also occur with pancreatitis
, peptic ulcers
, and other inflammatory abdominal conditions.
Treatment may include addressing the underlying cause and/or dietary modifications (small feedings or a liquid diet) and surgery.
Last updated: 12/18/2015
What are the signs and symptoms of superior mesenteric artery syndrome?
The signs and symptoms of superior mesenteric artery syndrome vary but may include:
- 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 in the left side.
Last updated: 5/16/2016
What causes superior mesenteric artery syndrome?
The superior mesenteric artery arises from the aorta and is enveloped in fatty and lymphatic tissue (mesenteric pad). It forms an angle of about 38 º and 65º with the abdominal aorta (due in part, to the mesenteric fat pad). Because the third part of the duodenum courses between the angle formed by the superior mesenteric artery and aorta, any factor that sharply narrows the angle between the aorta and superior mesenteric artery can cause entrapment and compression of the third part of the duodenum resulting in superior mesenteric artery syndrome. This angle correlates with body mass index.
A variety of factors can contribute to the narrowing of the aorto-mesenteric angle:
- Significant weight loss: Is the most common factor because it leads to loss of the mesenteric fat pad. Weight loss may occur with severe, debilitating illnesses, trauma, surgery, prolonged bed rest and anorexia nervosa
- Corrective spinal surgery for scoliosis: This procedure lengthens the spine displacing the superior mesenteric artery origin and reduces mobility of the mesenteric artery because of the cast
- Congenital defects: Including a short ligament of Treitz (the tissue that suspends the duodenum in the normal position) or an abnormally low origin of the superior mesenteric artery
- Peritoneal adherences: Caused by inflammatory diseases in the abdomen (pancreatitis, peptic ulcers and others) and by previous abdominal surgeries.
There are some reports about more than one case in the same family and one report about affected identical twins, which suggests a genetic predisposition in some patients.
There are also several reported cases of superior mesenteric artery syndrome associated with celiac axis compression syndrome.
Last updated: 12/18/2015
How might superior mesenteric artery syndrome be treated?
Treatment for superior mesenteric artery syndrome typically focuses on addressing the underlying cause of the condition.
For example, symptoms often improve after lost weight is restored or a body cast is removed.
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.
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.
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.
Surgery options are:
- 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
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