Bariatric Surgery

Cleveland-Clinic-FemaleBariatric surgery

Bariatric surgical procedures are an option for treating severe obesity, by reducing intake or absorption of calories. There are various options, all of which have potential complications.

A 2014 Cochrane review concluded that surgery results in greater improvement in weight loss outcomes and weight-associated comorbidities compared with non-surgical interventions, regardless of the type of procedures used.

Bariatric surgery should always be performed in a specialist center and long-term follow-up of patients is necessary.

The number of procedures rose sharply by 70% between 2008/2009, although recording and coding changes contributed to this.  For more general information regarding obesity and its management .


Bariatric surgery is an option in severely obese patients, where lifestyle and medication have been evaluated but found not to be effective. Surgery can be combined with other treatments. Referrals are usually made via a specialised obesity management service. There are clear guidelines from the National Institute for Health and Care Excellence (NICE) about who should be considered for bariatric surgery. In the 2014 update of the guidelines, recommendations for earlier consideration of bariatric surgery for those people with diabetes mellitus were introduced. Prior to this, a report from the Office of Health Economics suggested that the number of procedures performed is far less than could be predicted from UK obesity prevalence figures and that commissioners of services are not complying with the guidelines or are interpreting them too stringently.


  • BMI ≥40 kg/m2 OR BMI 35-40 kg/m2 with other significant disease (eg, type 2 diabetes, hypertension) that could be improved by weight loss and:
    • All appropriate non-surgical measures have failed to achieve or maintain adequate clinically beneficial weight loss.
    • They are receiving or will receive intensive specialist management.
    • They are generally fit for anaesthesia and surgery.
    • They commit to the need for long-term follow-up.
  • As a first-line option if BMI of >50 kg/m2 and surgical intervention is considered appropriate (and consider orlistat before surgery if the waiting time is long).
  • For people with recent onset (within the previous ten years) type 2 diabetes mellitus:
    • If BMI ≥35 kg/m2, expedite assessment for bariatric surgery (as long as they will receive assessment in a specialist tier 3 service.)
    • Consider assessment for bariatric surgery in a tier 3 service if BMI is 30-34.9 kg/m2.
    • For those of Asian origin, consider assessment for bariatric surgery in a tier 3 service at lower BMI than other populations.

Young people
Surgery is not generally recommended, as it is fraught with ethical issues and the potential long-term benefits and complications are not yet know . doctors suggests that it may be considered in exceptional circumstances, if:

  • They have achieved or nearly achieved physiological maturity.
  • They are receiving or will receive intensive specialist management. This will include
    • Full information on procedures available and risks and benefits.
    • Management of comorbidities.
    • Psychological support before and after surgery.
    • Regular postoperative assessment, including specialist dietetic and surgical follow-up
    • Information about access to plastic surgery, such as apronectomy, where appropriate.
    • Access to suitable equipment for obese young people.
    • Assessment of fitness for anaesthesia and surgery.
  • They have had a comprehensive psychological, educational, family and social assessment before undergoing bariatric surgery.
  • They have had a full medical evaluation, including genetic screening or assessment before surgery to exclude rare, treatable causes of obesity. They should also have had a specialist assessment to exclude eating disorders.

There are increasing demands for bariatric surgery to be considered as a valid option in children and adolescents in the face of the increasing prevalence of obesity in this age group.

Some research suggests that it may also be worthwhile for those with a BMI of 30-35.

Few procedures are performed on the elderly but the risk is thought to be no higher than any other gastrointestinal procedure.[9] The risk:benefit ratio for those with a BMI >70 is currently being researched but one study of 49 patients reported that it was a safe procedure.

Contra-indications and cautions

  • Unfit for surgery.
  • Uncontrolled alcohol or drug dependency.
  • Uncontrolled emotional disorders.
  • Lack of ability to understand surgery, consequences, need for follow-up.
  • Some centres advise pre-operative psychiatric and nutritionist assessment.

Types of procedure for bariatric surgery


  • 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.
    • It may be that these methods of action overlap, and that the effect is physiological, via endocrine and neuronal means, rather than purely limiting calorie intake.
  • There are various procedures and variations on them, and these have evolved over a period of 50 years. The vast majority are now performed with a minimally invasive or laparoscopic approach.

Bariatric surgery procedures currently used


  • Restrictive:
    • Laparoscopic adjustable gastric banding.
    • Vertical sleeve gastrectomy.
  • Malabsorptive:
    • Biliopancreatic diversion with/without duodenal switch.
  • Both restrictive and malabsorptive:
    • Roux-en-Y gastric bypass (RYGB).S_6_2_Fig_2_Bariatric_surgery
    • Other types of gastric bypass.
  • Other procedures:
    • Gastric stimulation.
    • Intragastric balloon.

Choice of procedure

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

  • Fitness for surgery.
  • Degree of obesity.
  • Goals.
  • Comorbidities.
  • Best available evidence about effectiveness and long-term effects.
  • Facilities available, and experience of surgeon.
  • Some centres have a two-stage approach, using a restrictive procedure initially, followed by a malabsorptive procedure later if necessary.

The use of the laparoscopic sleeve gastrectomy has increased in recent years.

The most commonly used procedures in the UK currently are laparoscopic adjustable gastric banding, sleeve gastrectomy and gastric bypass.[2]

Many studies and meta-analyses have tried to make comparisons between available procedures. The Cochrane review of 2014 concluded that outcomes were similar between RYGB and sleeve gastrectomy, and both of these procedures had better outcomes than adjustable gastric banding.

In those with very high BMI, biliopancreatic diversion with duodenal switch were found to result in greater weight loss than RYGB. It was noted that across all studies adverse event rates and re-operation rates were generally poorly reported, and the long-term effects of surgery remain unclear.

Explanation of bariatric procedures

  • 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). The RYGB is the usual procedure at the current time.
  • Biliopancreatic diversion: is a more extensive form of the gastric bypass, with the gastric pouch joined to the ileum, totally bypassing the duodenum and jejunum. 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. This is a complex operation which takes some hours to complete.
  • Gastric stimulation: uses an implanted pacemaker-type device to produce electrical gastric stimulation, thought to cause a feeling of satiety.
  • Intragastric balloon: 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 have been complications such as gastric erosions and ulcers. It is therefore usually removed after six months.
  • Endoscopic techniques: apart from balloon insertion, various other endoscopic procedures are being developed but are not currently in common NHS use. These are collectively known as primary obesity surgery endolumenal (POSE).


Those who have had bariatric surgery should be followed up by the specialist bariatric service for a minimum of two years. This should include:

  • Monitoring nutritional intake (including protein and vitamins) and mineral deficiencies.
  • Dietary and nutritional advice and support.
  • Physical activity advice and support.
  • Psychological support.
  • Monitoring for comorbidities.
  • Medication review.

After discharge from bariatric surgery service follow-up, ensure that all people are offered at least annual monitoring of nutritional status and appropriate supplementation according to need. The


Benefits of bariatric surgery procedures

  • Weight loss. In a long-term Swedish trial, weight loss averaged 18% after 20 years.
  • Remission of diabetes mellitus. The Swedish trial showed a 72% remission rate two years after surgery.
  • The Swedish study also reported a reduction in overall mortality of 29%, and a reduction in the incidence of myocardial infarction, stroke and cancer.
  • Evidence suggests that non-alcoholic fatty liver disease (including steatosis, steatohepatitis and fibrosis) appears to improve or completely resolve in the majority of patients after bariatric surgery-induced weight loss.

Complications and disadvantages of surgery

Pre-operative discussion is important; patients may have unrealistic ideas about the amount of weight they are likely to lose, the need for follow-up and the potential complications. Peri-operative mortality is low at less than 0.3%, and is declining.

The incidence of complications within the first six months varies from 4-25%, and depends on procedure used, duration of follow-up and individual patient characteristics. Complications to consider include:

  • peri-operative complications as for any abdominal surgery include venous thromboembolism. The use of prophylaxis has reduced the incidence of deep vein thrombosis and pulmonary embolism considerably.
  • Possible complications of banding are band slippage, leakage, infection or migration.
  • Surgical complications of bypass surgery include leakage or stenosis of the stoma, gastrointestinal ulcers or bleeding, small bowel obstruction and hernias.
  • Nausea and vomiting may occur due to overeating or to stenosis at the surgery site.
  • Dumping syndrome: symptoms are flushing, light-headedness, palpitations, fatigue and diarrhea, typically triggered by sugar after a RYGB. It is a neurohormonal reaction. It may help to discourage overeating.
  • Malnutrition: micronutrient deficiencies are a recognised problem, especially with malabsorptive procedures. Iron-deficiency anemia is the most common complication. Calcium, zinc, folate and vitamin D 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.
  • Gallstones can develop as a consequence of rapid weight loss.
  • Hyperoxaluria which can be mitigated to some extent by aggressive fluid intake, oral calcium and citrate supplementation.
  • Inadequate weight loss and weight regain. The latter is affected by behavioral patterns that can be assessed pre-operatively in order to identify individuals particularly at risk.
  • Up to 35% may require revision procedures, particularly in gastric banding.
  • Bariatric surgery patients show a higher suicide rate than the general population.
  • Removal of excess skin after significant weight loss usually needs follow up with your surgeon for best way to do it.

Bariatric Surgery Procedures

Bariatric surgical procedures cause weight loss by restricting the amount of food the stomach can hold, causing malabsorption of nutrients, or by a combination of both gastric restriction and malabsorption. Bariatric procedures also often cause hormonal changes. Most weight loss surgeries today are performed using minimally invasive techniques (laparoscopic surgery).

The most common bariatric surgery procedures are gastric bypass, sleeve gastrectomy, adjustable gastric band, and biliopancreatic diversion with duodenal switch. Each surgery has its own advantages and disadvantages.


Gastric Bypass

The Roux-en-Y Gastric Bypass – often called gastric bypass – is considered the ‘gold standard’ of weight loss surgery and is the most commonly performed bariatric procedure worldwide.

The Procedure

There are two components to the procedure. First, a small stomach pouch, approximately one ounce or 30 milliliters in volume, is created by dividing the top of the stomach from the rest of the stomach. Next, the first portion of the small intestine is divided, and the bottom end of the divided small intestine is brought up and connected to the newly created small stomach pouch. The procedure is completed by connecting the top portion of the divided small intestine to the small intestine further down so that the stomach acids and digestive enzymes from the bypassed stomach and first portion of small intestine will eventually mix with the food.

The gastric bypass works by several mechanisms. First, similar to most bariatric procedures, the newly created stomach pouch is considerably smaller and facilitates significantly smaller meals, which translates into less calories consumed. Additionally, because there is less digestion of food by the smaller stomach pouch, and there is a segment of small intestine that would normally absorb calories as well as nutrients that no longer has food going through it, there is probably to some degree less absorption of calories and nutrients.

Most importantly, the rerouting of the food stream produces changes in gut hormones that promote satiety, suppress hunger, and reverse one of the primary mechanisms by which obesity induces type 2 diabetes.


  1. Produces significant long-term weight loss (60 to 80 percent excess weight loss)
  2. Restricts the amount of food that can be consumed
  3. May lead to conditions that increase energy expenditure
  4. Produces favorable changes in gut hormones that reduce appetite and enhance satiety
  5. Typical maintenance of >50% excess weight loss


  1. Is technically a more complex operation than the AGB or LSG and potentially could result in greater complication rates
  2. Can lead to long-term vitamin/mineral deficiencies particularly deficits in vitamin B12, iron, calcium, and folate
  3. Generally has a longer hospital stay than the AGB
  4. Requires adherence to dietary recommendations, life-long vitamin/mineral supplementation, and follow-up compliance


Sleeve Gastrectomy

The Laparoscopic Sleeve Gastrectomy – often called the sleeve – is performed by removing approximately 80 percent of the stomach. The remaining stomach is a tubular pouch that resembles a banana.

The Procedure

This procedure works by several mechanisms. First, the new stomach pouch holds a considerably smaller volume than the normal stomach and helps to significantly reduce the amount of food (and thus calories) that can be consumed. The greater impact, however, seems to be the effect the surgery has on gut hormones that impact a number of factors including hunger, satiety, and blood sugar control.

Short term studies show that the sleeve is as effective as the roux-en-Y gastric bypass in terms of weight loss and improvement or remission of diabetes. There is also evidence that suggest the sleeve, similar to the gastric bypass, is effective in improving type 2 diabetes independent of the weight loss. The complication rates of the sleeve fall between those of the adjustable gastric band and the roux-en-y gastric bypass.


  1. Restricts the amount of food the stomach can hold
  2. Induces rapid and significant weight loss that comparative studies find similar to that of the Roux-en-Y gastric bypass. Weight loss of >50% for 3-5+ year data, and weight loss comparable to that of the bypass with maintenance of >50%
  3. Requires no foreign objects (AGB), and no bypass or re-routing of the food stream (RYGB)
  4. Involves a relatively short hospital stay of approximately 2 days
  5. Causes favorable changes in gut hormones that suppress hunger, reduce appetite and improve satiety


  1. Is a non-reversible procedure
  2. Has the potential for long-term vitamin deficiencies
  3. Has a higher early complication rate than the AGB

Adjustable Gastric Band

The Adjustable Gastric Band – often called the band – involves an inflatable band that is placed around the upper portion of the stomach, creating a small stomach pouch above the band, and the rest of the stomach below the band.

The Procedure

The common explanation of how this device works is that with the smaller stomach pouch, eating just a small amount of food will satisfy hunger and promote the feeling of fullness. The feeling of fullness depends upon the size of the opening between the pouch and the remainder of the stomach created by the gastric band. The size of the stomach opening can be adjusted by filling the band with sterile saline, which is injected through a port placed under the skin.

Reducing the size of the opening is done gradually over time with repeated adjustments or “fills.” The notion that the band is a restrictive procedure (works by restricting how much food can be consumed per meal and by restricting the emptying of the food through the band) has been challenged by studies that show the food passes rather quickly through the band, and that absence of hunger or feeling of being satisfied was not related to food remaining in the pouch above the band. What is known is that there is no malabsorption; the food is digested and absorbed as it would be normally.

The clinical impact of the band seems to be that it reduces hunger, which helps the patients to decrease the amount of calories that are consumed.


  1. Reduces the amount of food the stomach can hold
  2. Induces excess weight loss of approximately 40 – 50 percent
  3. Involves no cutting of the stomach or rerouting of the intestines
  4. Requires a shorter hospital stay, usually less than 24 hours, with some centers discharging the patient the same day as surgery
  5. Is reversible and adjustable
  6. Has the lowest rate of early postoperative complications and mortality among the approved bariatric procedures
  7. Has the lowest risk for vitamin/mineral deficiencies


  1. Slower and less early weight loss than other surgical procedures
  2. Greater percentage of patients failing to lose at least 50 percent of excess body weight compared to the other surgeries commonly performed
  3. Requires a foreign device to remain in the body
  4. Can result in possible band slippage or band erosion into the stomach in a small percentage of patients
  5. Can have mechanical problems with the band, tube or port in a small percentage of patients
  6. Can result in dilation of the esophagus if the patient overeats
  7. Requires strict adherence to the postoperative diet and to postoperative follow-up visits
  8. Highest rate of re-operation

Biliopancreatic Diversion with Duodenal Switch (BPD/DS) Gastric Bypass

The Biliopancreatic Diversion with Duodenal Switch – abbreviated as BPD/DS – is a procedure with two components. First, a smaller, tubular stomach pouch is created by removing a portion of the stomach, very similar to the sleeve gastrectomy. Next, a large portion of the small intestine is bypassed.

The Procedure

The duodenum, or the first portion of the small intestine, is divided just past the outlet of the stomach. A segment of the distal (last portion) small intestine is then brought up and connected to the outlet of the newly created stomach, so that when the patient eats, the food goes through a newly created tubular stomach pouch and empties directly into the last segment of the small intestine. Roughly three-fourths of the small intestine is bypassed by the food stream.

The bypassed small intestine, which carries the bile and pancreatic enzymes that are necessary for the breakdown and absorption of protein and fat, is reconnected to the last portion of the small intestine so that they can eventually mix with the food stream. Similar to the other surgeries described above, the BPD/DS initially helps to reduce the amount of food that is consumed; however, over time this effect lessens and patients are able to eventually consume near “normal” amounts of food. Unlike the other procedures, there is a significant amount of small bowel that is bypassed by the food stream.

Additionally, the food does not mix with the bile and pancreatic enzymes until very far down the small intestine. This results in a significant decrease in the absorption of calories and nutrients (particularly protein and fat) as well as nutrients and vitamins dependent on fat for absorption (fat soluble vitamins and nutrients). Lastly, the BPD/DS, similar to the gastric bypass and sleeve gastrectomy, affects guts hormones in a manner that impacts hunger and satiety as well as blood sugar control. The BPD/DS is considered to be the most effective surgery for the treatment of diabetes among those that are described here.


  1. Results in greater weight loss than RYGB, LSG, or AGB, i.e. 60 – 70% percent excess weight loss or greater, at 5 year follow up
  2. Allows patients to eventually eat near “normal” meals
  3. Reduces the absorption of fat by 70 percent or more
  4. Causes favorable changes in gut hormones to reduce appetite and improve satiety
  5. Is the most effective against diabetes compared to RYGB, LSG, and AGB


  1. Has higher complication rates and risk for mortality than the AGB, LSG, and RYGB
  2. Requires a longer hospital stay than the AGB or LSG
  3. Has a greater potential to cause protein deficiencies and long-term deficiencies in a number of vitamin and minerals, i.e. iron, calcium, zinc, fat-soluble vitamins such as vitamin D
  4. Compliance with follow-up visits and care and strict adherence to dietary and vitamin supplementation guidelines are critical to avoiding serious complications from protein and certain vitamin deficiencies


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