Bariatric Surgery

Bariatric surgical procedures are an option for treating severe obesity, by reducing intake or absorption of calories. There are various procedures, all of which have potential complications. Bariatric surgery should always be performed in a specialist centre, and long term follow-up of patients is necessary.

Bariatric surgery is an option in severely obese patients, where lifestyle/medication have not been effective. Surgery can be combined with other treatments. Referrals are usually made via a specialist obesity management service.

There are clear guidelines from NICE about who should be considered for bariatric surgery (see below). Some research suggests that it may also be worthwhile for those with a BMI 30-35.² The risk/benefit ratio is less certain for the young, the elderly and those with a BMI >70.³

• Inability to give informed consent, e.g immaturity or mental disability.
• Unfit for surgery.
• Some centres advise pre-operative psychiatric and nutritionalist assessment.

• Procedures are classified as restrictive, malabsorptive or both.
  • Restrictive procedures produce a feeling of fullness with lower food intake.
  • Malabsorptive procedures limit calorie uptake from the intestine.
• There are various procedures and variations on them. Many can be performed by laparoscopy.
• The most commonly used procedures are laparoscopic adjustable gastric banding and roux-en-Y gastric bypass.

Choice of procedure^1,4

Bariatric surgery should be performed by a specialist team in a tertiary centre. The choice of procedure is partly determined by local expertise; it is important that all operations are performed by an experienced surgeon. Factors to take into account are:

• Fitness for surgery
• Degree of obesity
• Some centres have a 2-stage approach, using a restrictive procedure initially followed by a malabsorptive procedure later if necessary.
• Tailoring the procedure to the patient may be a way forward.² One centre allocated choice of procedure according to the patients' eating patterns.⁵

Explanation of bariatric procedures^2,3

• Laparoscopic adjustable gastric banding: places a constricting ring around the stomach, below the gastro-oesphageal junction. The bands incorporate an inflatable balloon which can adjust the size of the ring, to regulate food intake.
• Sleeve gastrectomy: most of the stomach is removed, leaving a sleeve-shaped cylinder of stomach with reduced capacity. This procedure is irreversible.
• Gastric bypass: creates a small gastric pouch (restrictive) joined to the jejunum, bypassing the duodenum and proximal jejunum (malabsorptive).
• Biliopancreatic diversion: is a more extensive form of the gastric bypass, with the gastric pouch joined to the ileum. It produces more extreme malabsorption.
• Duodenal switch: Biliopancreatic diversion is sometimes performed with a duodenal switch. This produces a short distal length of small intestine, severely limiting caloric absorption.
• Jejuno-ileal bypass is no longer used, having a high morbidity and mortality.
• Gastric stimulation: uses an implanted pacemaker-type device to produce electrical gastric stimulation.⁶
• Intragastric ballon: this is an endoscopic rather than surgical procedure, placing a silicone balloon inflated in the stomach to promote a feeling of satiety. There is insufficient evidence to assess its effectiveness, and there were complications such as gastric erosions and ulcers.⁷

• Regular specialist dietetic review: micronutrients will need monitoring.
• Patient support groups should be offered.

• Weight loss - although this is not guaranteed. Generally, the malabsorptive procedures seem to produce greater weight loss, but carry higher risks. In one trial, long-term weight loss averaged 25% with gastric bypass and 14% with gastric banding.⁸
• Reduction in co-morbidities related to obesity, such as diabetes.⁹ Benefits in the longer term (10 years) may be less than those seen at earlier follow-up.³
• Reduction in mortality: a large RCT over 10 years found that bariatric surgery reduced overall mortality compared to conventional treatment.⁸ Deaths rates from diabetes, heart disease and cancer are probably reduced, though deaths from some causes increased (see complications).¹⁰
• Possibly, there are beneficial metabolic effects through altered release of gut hormones; this may be relevant to patients with diabetes.²

Preoperative discussion is important; patients may have unrealistic ideas about the amount of weight they are likely to lose, and the need for follow-up and potential complications.

• Perioperative complications as for any abdominal surgery: these include venous thromboembolism and death. The less radical (such as gastric banding) and the laparoscopic procedures have fewer serious complications.⁴
• Possible complications of banding are: band slippage, leakage, infection or migration.²
• Surgical complications of bypass surgery include: leakage or stenosis of the stoma, G-I ulcers or bleeding, small bowel obstruction and hernias.
• Nausea and vomiting due to over-eating or to stenosis at the surgery site.
• Dumping syndrome: symptoms are flushing, lightheadedness, palpitations, fatigue and diarrhoea; typically triggered by sugar after a Roux-en-Y gastric bypass. It is a neurohormonal reaction. It may help to discourage over-eating.
• Malnutrition: micronutrient deficiencies are a recognised problem, especially with malabsorptive procedures. Iron, calcium, folate and fat-soluble vitamin deficiencies can occur. Thiamine, B12 and copper deficiencies may cause neurological symptoms and should be remembered. Protein-calorie malnutrition can also occur. Long-term follow-up is important.
• Inadequate weight loss.
• One retrospective study found that some causes of mortality such as suicide, were higher after bariatric surgery compared to controls. Overall mortality rates favoured surgery.¹⁰
• If the original operation fails, revisional surgery should only be undertaken only in specialist centres by surgeons with extensive experience - due to the high complication and increased mortality rate.¹