Female Scientist Using Microscope
 

History

SMAS was first described in 1861 by a pathologist named Carl Freiherr von Rokitansky. Sadly it remained an undefined pathology until 1927 when Wilkie published the first comprehensive series of patients who suffered from it. The Duodenojejunostomy was the first treatment to be suggested for SMAS. This was suggested by a doctor of the name of Bloodgood. This surgery was first performed by Dr Stavely in 1908. Since then it is still a common procedure done on SMAS patients. The very first laparoscopic duodenojejunostomy was done in 1997.

What is SMAS?

SMAS or Superior Mesenteric Artery Syndrome is the obstruction of the 3rd portion of the duodenum due to compression by the Superior Mesenteric Artery (SMA ) towards the Abdominal Aorta ( AA ) reducing the angle between these two structures to 6 – 22° ( normal 28 – 65° ) hence decreasing the aortomesenteric distance to 2 – 8 mm ( normal 10 – 34mm ). The obstruction can be intermittent, partial or complete.

Symptoms

  • 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 pain

What causes SMAS?

SMAS is typically caused by the loss of the mesenteric fat pad. The fat pad is fatty tissue that surrounds the mesenteric artery. The SMA forms an angle with the abdominal aorta due in part to the fat pad and part of the duodenum sits within this angled space. Anything that severely narrows this angle between the aorta and the SMA can cause compression of the duodenum. This is what results in SMAS.
There are also some reports of familial cases of SMAS. One of those reports is a case study of affected identical twins. This suggests that there may be a genetic predisposition to SMAS in some people.

What causes loss of the mesenteric fat pad?

The most common cause of loss of the mesenteric fat pad is significant weight loss caused by medical disorders, psychological disorders or surgery. Comorbidities can also contribute to the loss of the fat pad which then causes SMAS.

Clinical Presentation & Diagnostic Workup

SMAS is often considered a diagnosis of exclusion. This means that after going through a full GI workup you may find your doctor giving you this diagnosis. Tests that may be needed to evaluate a person with symptoms of SMAS include. X-rays, Upper GI series, Ultrasound, Arteriography and CT scan. Finding out if you have SMAS is often a long process which can lead to a delayed diagnosis. This can result in significant complications for some patients.

Complications

  • Accumulation of gas in the portal vein

  • Gastric Pneumatosis

  • Formation of an obstructing duodenal bezoar 

  • Electrolyte Abnormalities

  • Gastric Perforation

Management

  • Meal Replacement Shakes

  • High Calorie Diets

  • Proper Positioning After Eating

    • Standing

    • Sitting in the knee to chest position

    • Lying down on your left side

  • Nasogastric Decompression (NG Tube)

  • IV Nutritional Support

  • Jejunostomy feeding tube (J Tube)

  • Metoclopramide Treatment

  • Surgery

Surgical Options

There are 3 common surgical options for SMAS, Strong’s Procedure, Gastrojejunostomy and Duodenojejunostomy. 

  • 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.

Consequential Cascade of the Disease Process

Superior Mesenteric Artery Syndrome (SMAS) is a rare condition that involves the small intestines. This condition occurs when the duodenum is compressed between two arteries. One being the Aorta and other being a branch of the Aorta called the superior mesenteric artery (SMA).

We've created a page on our website that can help you find research articles and helpful websites to learn more about Superior Mesenteric Artery Syndrome (SMAS).