Teaching Case

Young female with history of laparoscopic gastric banding positioning five years earlier, suffering from decreased food intake, vomiting and sudden weight loss since 3 weeks. Seen at emergency department, with laboratory evidence of dehydration and malnutrition, specifically hypokalemia (2.5 mmol/L), low total proteins and prealbumin (21 mg/dL).

Nine months earlier, she had upper digestive endoscopy with unremarkable findings including normal gastric mucosa. Initial radiographs (Fig.1) showed gaseous overdistension of the proximal gastric pouch, and the band appeared in a near-horizontal position relative to longitudinal spine axis consistent with an abnormal (~90°) phi angle.
Further CT investigation (Fig.2), including contrast-enhanced acquisition following sipping of some water-soluble iodinated contrast by mouth, showed confirmed markedly distended stomach with abundant intraluminal fluid, with entire fundus and part of gastric body herniated above the distally slipped band, contracted stoma and some perigastric fluid.
Following removal of fluid (1 liter) by nasogastric intubation and partial detension of gastric band, repeated radiographs (Fig.3) showed persistent overdistension of upward herniated stomach with air-fluid level indicating impaired transit.
After total parenteral nutrition, the patient underwent repeated surgery with confirmation and removal of slipped gastric banding, and resection of herniated sac.

Bariatric surgery is a fast-growing specialty with favourable risk-benefit profile, which consistently achieves substantial weight loss and reduces metabolic disorders and cardiovascular risk in morbidly obese individuals [1, 2].
Albeit sleeve gastrectomy is increasingly used, laparoscopic adjustable gastric banding (LABG) remains the commonest and less invasive bariatric operation. The silicon band with inflatable inner cuff is positioned 2 cm distal to the gastro-oesophageal junction, thus creating a small (15-30 ml capacity) proximal “gastric pouch” and causing early satiety from delayed food bolus transit. The stomal caliber is adjusted by injecting or aspirating saline via the subcutaneous port secured on the rectus muscle sheath, connected to the band via kink-resistant tubing. Compared to Roux-en-Y gastric bypass, LABG is reversible and has very few early complications, but achieves less and slower weight loss. Furthermore, concerns are increasing over its long-term efficacy and safety, with complications and need for reoperation within 10 years reported in 33-40% and 9-22% of patients, respectively [3-6].
Since bariatric patients often present to emergency departments with nonspecific complaints months or years after surgery, radiologists need familiarity with normal and complicated postoperative appearances. Following LABG, the commonest complication is band slippage (BS), which refers to cephalad herniation of the distal stomach through the band, secondary to inadequate fixation and increased pressure on the proximal pouch. Favoured by poor nutritional habits, BS occurs in 4.9-8.1% (up to 15-22% in some series) of patients. Manifestations include abdominal pain, food intolerance or dysphagia, nausea/vomiting, severe reflux symptoms. Untreated BS may result in chronic stomal stricture, or lead to further complications such as obstruction, volvulus, gastric ischemia and haemorrhage [3-8].
Radiographically, the proximal gastric pouch is eccentrically and often markedly dilated (> 4cm), and the radio-opaque gastric band projects left to the spine, roughly 5 cm below the diaphragm. Compared to normal inclination, malpositioned bands are rotated clockwise to a more horizontal position or oriented “en face”. As in this patient, use of water-soluble oral contrast may allow to assess patency of LABG, and CT may further elucidate postsurgical anatomy [9-12].
The commonest differential diagnosis of BS is acute (from band overtightening) or chronic (from excessive filling and adhesions) stomal stricture, with concentric pouch dilatation, nonobstructed stoma and normal band positioning, generally relieved by band loosening. Conversely, patients with SB are treated by urgent deflation, but ultimately require surgical band removal or conversion to another surgery in over half of cases [7, 8].

Written informed patient consent for publication has been obtained.