Discussion

This case report of feeding tube placement distal to the obstruction via the endoscopic approach for SMA syndrome in a postoperative patient showed that feeding tube placement was safe and useful, particularly in a perioperative high-risk patient, to improve SMA syndrome quickly. SMA syndrome studies have estimated the incidence at 0.013%–0.3% in the general population.1 It is defined as the compression of the third part of the duodenum due to the narrowing of the space between the SMA and the aorta, mainly by the loss of the mesenteric fat pad.2 The most common factor reducing the angle and distance between the aorta and the SMA is significant weight loss leading to the loss of mesenteric fat pads due to a medical disorder, psychological disorder or surgery.3–7 Patients may have acute (eg, postoperative) or slowly progressive symptoms, consistent with the symptoms of proximal small bowel obstruction. Patients with mild obstruction may have only postprandial epigastric pain and early satiety, while those with more advanced obstruction may have severe nausea, bilious emesis and weight loss. Patients may also have symptoms of reflux.8 9 The diagnosis of SMA syndrome may be aided by radiological, angiographic, ultrasonic and endoscopic studies. CT angiography is now the investigation of choice, with endoscopy and ultrasound playing adjunctive roles.10 We employed a CT scan with confirmatory findings. As a general rule, few criteria should be present on imaging11 12 : (1) duodenal obstruction with an abrupt cut-off in the third portion and active peristalsis; (2) an aortomesenteric artery angle of ≤25°, which is the most sensitive measure of diagnosis, particularly if the aortomesenteric distance is ≤8 mm; and (3) high fixation of the duodenum by the ligament of Treitz, an abnormally low origin of the SMA, or anomalies of the SMA. The goal of SMA syndrome treatment is weight gain, the relief of intestinal obstruction symptoms and the correction of precipitating factors. Initial treatment is usually conservative non-operative treatment, which includes gastrointestinal decompression using nasogastric tube placement, the correction of electrolyte abnormalities and nutritional support.13 Among these, nutritional support is the major component of conservative treatment to increase the aortomesenteric angle and improve symptoms by increasing the intermembrane fat pad and prevent duodenal compression. Enteral nutrition is preferred, taking frequent small meals of nutritious liquid, lying on the left side or prone following meals.6 13 14 Metoclopramide is also advised to relieve symptoms. TPN can be useful when enteral feedings are not tolerated.15 16

However, except for paediatric patients and some adults who have a brief history of symptoms, the success rate of conservative treatment is not high. Particularly, patients who had chronic symptoms had unfavourable outcomes from nutritional support alone,17 and many patients failed and finally required surgical treatment.15 18–20 The patient in this case also did not gain body weight for 6 weeks despite TPN and electrolyte supplementation and did not experience symptom improvement. Surgery has still been the only accepted treatment if conservative treatment fails.18 Many surgical procedures have been developed over the years, and minimally invasive duodenojejunostomy is now widely accepted as the main treatment for SMA syndrome.4 Previous studies have shown a higher success rate of surgical treatment than conservative treatment and suggested an earlier surgical intervention to avoid creating a vicious cycle of symptoms.19 21 22 However, surgical treatment has potential operative and postoperative risks, particularly for the patients who underwent surgery, as in this case, and have (1) poor nutritional status, (2) changes in anatomical structures and intraperitoneal adhesions, and (3) not fully recovered from previous surgery and/or had comorbidities. In contrast, jejunal feeding tube placement past the obstruction to allow continuous enteral feeding is safe and useful. If the patient cannot tolerate oral feeding, this treatment can be employed to support weight gain.6 Several previous cases have reported the successful treatment of SMA syndrome by transpyloric jejunal feeding past the point of the obstruction.9 23 24 However, these were cases of paediatric patients or patients with no surgical history. These studies also did not report the detailed treatment and recovery process. In particular, there was no description of the role of endoscopy in jejunal feeding tube placement. The present case was performed safely by an endoscopist who had ample experience with colonic stent insertion. When passing through the obstruction of the duodenal third portion, the risk was evaluated by an endoscopist, who decided whether to proceed with the procedure. Endoscopy-assisted feeding tube placement followed by the dual enteral and parenteral nutrition might be applied as first-line therapy in the conservative treatment of SMA syndrome because (1) an experienced endoscopist can safely attempt it with a high success rate, (2) SMA syndrome can be diagnosed and treated simultaneously, (3) it allows the patient to reach the target weight faster than conventional TPN, and (4) it can also avoid electrolyte imbalance and hepatotoxicity due to TPN. If endoscopy-assisted feeding tube placement is available for highly selected patients, especially for the patients who have a high risk for surgery or have previously had surgery, the approach might be useful.