by Archit Garg, Lara Calegari

A 35-year-old Hispanic woman, who had endometriosis surgery in 2018, experienced worsening epigastric pain, severe nausea, vomiting, and diarrhea for one day. The patient had no history of prior episodes, personal or family history of IBS, IBD, or cancers. Over four months, she experienced unintentional 25-pound weight loss, poor appetite causing her to stop eating early, and significant emotional distress after losing her job and getting divorced. Her symptoms consisted of severe, diffuse abdominal pain aggravated by recumbency, with temporary relief following emesis. Although she had no fever, sick contacts, or recent travel, she did report chills. On physical examination, the abdomen was distended and mildly tender to the touch. Laboratory findings indicated leukocytosis in the absence of bandemia. Please see the abdominal CT scan in the Figure 1 and 2.

Question 1: Which of the Following Diagnoses is Most Likely in this Case?

A) Celiac disease

B) Superior mesenteric artery syndrome

C) Crohn’s disease

D) Lactose Intolerance

The Correct answer is B. 

Explanations:

This patient’s symptoms strongly suggest Superior Mesenteric Artery (SMA) syndrome. Rapid, substantial weight loss may cause the retroperitoneal fat pad and connective tissue to shrink, narrowing the angle of the aorta and superior mesenteric artery. This anatomical alteration may later lead to duodenal blockage.

Duodenal dilation proximally, with contrast unable to pass the duodenum’s third part (usually at a defined point of obstruction), is a diagnostic criterion. Typically, CT scans, the most sensitive diagnostic method, will show an aorto-superior mesenteric artery angle less than 25° and an aortomesenteric distance under 8 mm.

Option A: 

Celiac disease, an autoimmune disorder, triggers an immune response when gluten is consumed. Celiac disease’s typical symptoms—chronic diarrhea, bloating, and malabsorption—don’t explain this patient’s sudden onset of cramps, pain, nausea, vomiting, and diarrhea. A CT scan won’t diagnose celiac disease.  Confirmation requires serological testing (for anti-gluten, anti-gliadin, and anti-endomysial antibodies) plus a small intestine biopsy to look for villous atrophy.

Option C:

Characterized by chronic diarrhea, abdominal pain, fatigue, weight loss, and alternating relapses and remissions, Crohn’s disease is a chronic inflammatory disorder of the gastrointestinal tract.

Option D:

A lactase enzyme deficiency, which is characteristic of lactose intolerance, prevents the breakdown of complex carbohydrates present in food. Bloating, diarrhea, and abdominal discomfort are common after dairy consumption for those with lactose intolerance. Lactose intolerance shows unremarkable CT imaging, in contrast to SMA syndrome, where the aorto-SMA angle is reduced.

Conclusion

Characterized by duodenal compression from the SMA and aorta, SMA syndrome is a rare gastrointestinal disorder causing nausea, vomiting, positional abdominal pain, and weight loss. Diagnosis rests on CT or MRI imaging showing compression of the duodenum due to a narrowed aorto-SMA angle. Severe cases may necessitate surgery; otherwise, treatment is supportive.

Question 2:
What is the pathogenesis of this entity?

SMA syndrome is a potential complication in patients experiencing rapid weight loss due to various factors such as burns, prolonged immobility, bariatric surgery, cancer, or aortic aneurysm. The loss of retroperitoneal fat and connective tissue due to a sharp decrease in weight can narrow the aortomesenteric angle, potentially causing duodenal obstruction.¹

Question 3: How do you make the diagnosis?

The diagnosis of SMA syndrome is confirmed with imaging. Contrast imaging studies, either barium studies or CT imaging with oral contrast, can be used. A diagnostic criterion includes proximal duodenal enlargement and contrast medium inability to pass the third part of the duodenum, showing a specific blockage. An aorto-superior mesenteric artery angle under 25° is the best diagnostic indicator, especially when the aortomesenteric distance is below 8 mm.²

Question 4: What is the Management? 

SMA syndrome treatment depends on the individual patient. It can be managed conservatively with emphasis given on weight gain. To relieve duodenal pressure, a nasogastric tube can be used to empty the stomach and duodenum. Treatment starts with high-calorie nutritional drinks and a special diet.³ Tube feeding or total parenteral nutrition may be used if needed. Postural therapy, using a left lateral position, helps avoid duodenal compression from the superior mesenteric artery and aorta. Surgery is needed when conservative management proves ineffective.³
This could be gastrojejunostomy, transabdominal or laparoscopic duodenojejunostomy, or a more involved procedure. 

References

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