Superior mesenteric artery syndrome

A 17-year-old girl presented to the emergency department with constipation and bloodless vomiting for 3 weeks. The vomiting worsened after food ingestion. The patient was exhausted and underweight, although she did not suffer abdominal pain. At admission, the patient had unwillingly lost 10 kg over 2 years, resulting in a body mass index of 14. During this period, she started prevention medicine due to a loss of menstruation. The patient had no prior medical or surgical history. Blood tests revealed an increased sed rate (ESR) of 33 (normal range: 2-20) as the only outlier. A contrast-enhanced CT was ordered based on the acute exacerbating of vomiting and constipation, with ileus as the tentative diagnosis.

At the time of admission, a contrast-enhanced CT scan in the venous phase showed a decreased aortic-mesenteric distance of 3 mm and an aortic-mesenteric angle of 14 degrees. The stomach was enlarged with fluid and food down to the third duodenal segment. The affected intestines showed no signs of ischemia. CT proved there was no other pathology.

Upper gastrointestinal tract fluoroscopy within the same month was performed to examine the motility and possible stenosis. It showed a large and air-filled stomach with sparse peristalsis. The first and second segments of the duodenum were dilated up to 5 cm with normal peristalsis. Gastric retention remained 4 hours after contrast administration.

Two months later, a new fluoroscopy showed slightly better passage in the duodenum, though still obstructed. Gastric retention was still present.

After surgery, a CT showed sequelae to duodenojejunostomy and cholecystectomy with sparse free air. The aortic-mesenteric angle increased to 32 degrees and the distance to 20 mm. Aside from slight bleeding following the procedure, there were no significant complications.

Superior mesenteric artery syndrome (SMA syndrome) is a rare entity with a predilection for females and young people between the ages of 10 and 39 [1]. The most frequent symptoms are reported to be abdominal pain, vomiting, early satiety, and nausea. Most patients have a history of either acute weight loss or SMA syndrome secondary to orthopaedic and spinal surgery [2].

Computed tomography (CT) can, respectively, provide the aortomesenteric distance and the angle at the third part of the duodenum. The mean angle normally varies between 38° and 56°. The mean distance varies between 10-28 mm [1, 3]. A cutoff value of 22 degrees and 8 mm or below has been significantly correlated with SMA syndrome [4].

Both the aortomesenteric distance and angle correlate with BMI in a normal population; hence, a normal variant should be considered upon diagnosing SMA [3]. Furthermore, a CT examination can identify additional causes like neoplasms. This CT found no other obvious reasons for the symptoms besides SMA syndrome.

Ultrasound can also be utilized to assess SMA. A significant correlation between the measurements of CT and ultrasound has been established [4]. Neri et al [5] demonstrated that ultrasound is a viable method of diagnosing SMA. Furthermore, ultrasound in the supine position could assess the aorto-mesenteric angle in the non-symptomatic period, unlike their fluoroscopy findings.

Fluoroscopy may reveal signs of dilation in the first and second duodenal segments and a lack of peristaltic flow proximal to the third segment. Furthermore, a delayed gastric transit may be revealed [1].

MRI is not as readily available and rarely used in the setting of acute abdomen. However, diagnostic traits similar to CT have been found [6].

SMA with less than a month’s history seems more receptive to conservative treatment in the acute setting. A nasogastric tube placement for gastric and duodenal decompression can be effective [1]. Various surgical procedures have been performed, including gastrojejunostomy, duodenojejunostomy, and Strong’s operation. A review of 146 cases revealed duodenojejunostomy to have the best results in severe cases. Gastrojejunostomy was adequate for stomach decompression but not for relieving duodenal obstruction [7].

This case followed the suggested regimen of conservative treatment, initially in the first months, and then converted to duodenojejunostomy four months after the first admission. The clinicians were hesitant to perform surgery due to the patient’s age and variable symptoms. It was ultimately decided based on progressive abdominal pain and secondary cholecystitis. Four months following the duodenojejunostomy, the patient was well, with the BMI gradually increasing to 18,4 (6 kg increase). Fluoroscopy proved a normal gastric transit time.

This case further highlights the importance of considering SMA when a patient presents with a low BMI and abdominal discomfort.

Written consent has been obtained for the patient.