Bariatric Surgery

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Bariatric surgical procedures are an option for treating severe obesity, by reducing intake or absorption of calories. The number of procedures has been steadily rising over he years. In 2010/11, over 8,000 were performed.[1] There are various options, 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.

For more general information regarding obesity and its management, see separate articles Obesity in Adults and Obesity in Children.

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 Clinical Excellence (NICE) about who should be considered for bariatric surgery. 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 interpreting them too stringently.[3]

  • 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 for at least six months.
    • 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).
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 known.[4] NICE suggests that it may be considered in exceptional circumstances, if:
  • They have achieved or nearly achieved physiological maturity.
  • BMI ≥40 kg/m2 OR 35-40 kg/m2 with other significant disease (eg, type 2 diabetes, hypertension) that could be improved by weight loss.
  • All appropriate non-surgical measures have failed to achieve or maintain adequate clinically beneficial weight loss for at least six months.[4]
  • They are receiving or will receive intensive specialist management.
  • They are fit for anaesthesia and surgery.
  • They commit to the need for long-term follow-up.

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.[5]

Some research suggests that it may also be worthwhile for those with a BMI of 30-35.[6] Few procedures are performed on the elderly but the risk is thought to be no higher than any other gastrointestinal procedure.[7] 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.[8]

  • Unfit for surgery.
  • Uncontrolled alcohol or drug dependency.
  • Some centres advise pre-operative psychiatric and nutritionist 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.

Bariatric surgery procedures currently used

  • Restrictive:
    • Laparoscopic adjustable gastric banding.
    • Sleeve gastrectomy.
  • Malabsorptive:
    • Biliopancreatic diversion with/without duodenal switch.
  • Both restrictive and malabsorptive:
    • Roux-en-Y gastric bypass.
    • Other types of gastric bypass - eg, mini-gastric bypass.
  • Other procedures (considered experimental):
    • Gastric stimulation.
    • Intragastric balloon.

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Choice of procedure[2]

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. Factors to take into account are:

  • Fitness for surgery.
  • Degree of obesity.
  • Some centres have a two-stage approach, using a restrictive procedure initially, followed by a malabsorptive procedure later if necessary.

The popularity of gastric bypass and gastric banding has reduced in recent years in favour of laparoscopic sleeve gastrectomy.[11] The most commonly used procedures in the UK currently are laparoscopic adjustable gastric banding, sleeve gastrectomy and gastric bypass.[1]

Explanation of bariatric procedures[10]

  • 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.[12]
  • 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.[13]
  • 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.[14]
  • 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.
  • Endoscopic techniques: apart from balloon insertion, various other endoscopic procedures are being developed but are not currently in common use.[15]
  • Regular specialist dietetic review: micronutrients will need monitoring.
  • Patient support groups should be offered.
  • Weight loss - in a long-term Swedish trial, weight loss averaged 18% after 20 years.
  • The Swedish study also reported a reduction in overall mortality and in the incidence of diabetes, stroke, myocardial infarction and cancer.
  • Possibly, there are beneficial metabolic effects through altered release of gut hormones; this may be relevant to patients with diabetes.[17]
  • Recent 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.[18]

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 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.[20] Mortality rates have been gradually improving with one large recent series reporting a rate of 0.04-0.3 %.[21] 
  • Possible complications of banding are band slippage, leakage, infection or migration.[22]
  • Surgical complications of bypass surgery include leakage or stenosis of the stoma, gastrointestinal ulcers or bleeding, small bowel obstruction and hernias.
  • Nausea and vomiting due to overeating or to stenosis at the surgery site.
  • Dumping syndrome: symptoms are flushing, light-headedness, 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 overeating.
  • 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.
  • Another well-recognised metabolic complication is significant 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 behavioural patterns that can be assessed pre-operatively in order to identify individuals particularly at risk.[23]
  • Bariatric surgery patients show a higher suicide rate than the general population.[24]
  • If the original operation fails, revisional surgery should only be undertaken in specialised centres, by surgeons with extensive experience - due to the high complication and increased mortality rate.[2]

The National Confidential Enquiry into Patient Outcome and Death (NCEPOD) report

The NCEPOD report on bariatric surgery was published in 2012. In order to reduce mortality and morbidity associated with bariatric surgery, the following initiatives were suggested:[1]

  • Surgeons should undergo a minimum number of procedures before being allowed to operate unsupervised.
  • Service provision should be restricted to a number of accredited centres with a set minimum number of procedures per annum.
  • All patients must have access to the full range of specialised professionals appropriate for their needs in line with NICE guidelines.
  • Psychological support should be initiated at an earlier stage in the process.
  • Consent should be a two-stage process and should not be taken on the day of surgery.
  • A clear discharge plan should be provided to the GP as soon as possible, including detailed dietary advice.
  • Postoperative psychological advice should be made available if required.

Further reading & references

  1. Too Lean a Service?; National Confidential Enquiry into Patient Outcome and Death, 2012
  2. Obesity; NICE Clinical Guideline (2006)
  3. Shedding the Pounds: Obesity Management, NICE Guidance and Bariatric Surgery in England; Office of Health Economics, 2012
  4. Caniano DA; Ethical issues in pediatric bariatric surgery. Semin Pediatr Surg. 2009 Aug;18(3):186-192.
  5. Hsia DS, Fallon SC, Brandt ML; Adolescent bariatric surgery. Arch Pediatr Adolesc Med. 2012 Aug;166(8):757-66. doi: 10.1001/archpediatrics.2012.1011.
  6. Picot J, Jones J, Colquitt JL, et al; Weight loss surgery for mild to moderate obesity: a systematic review and economic evaluation. Obes Surg. 2012 Sep;22(9):1496-506. doi: 10.1007/s11695-012-0679-z.
  7. Varela JE, Wilson SE, Nguyen NT; Outcomes of bariatric surgery in the elderly. Am Surg. 2006 Oct;72(10):865-9.
  8. Eldar SM, Heneghan HM, Brethauer SA, et al; Laparoscopic bariatric surgery for those with body mass index of 70-125 kg/m2. Surg Obes Relat Dis. 2012 Nov-Dec;8(6):736-40. doi: 10.1016/j.soard.2011.09.024. Epub 2011 Oct 14.
  9. Guidelines for Clinical Application of Laparoscopic Bariatric Surgery; Society of American Gastrointestinal and Endoscopic Surgeons, 2008
  10. Bariatric services: Information for GPs; Musgrove Park Hospital, 2007
  11. Nguyen NT, Nguyen B, Gebhart A, et al; Changes in the makeup of bariatric surgery: a national increase in use of laparoscopic sleeve gastrectomy. J Am Coll Surg. 2013 Feb;216(2):252-7. doi: 10.1016/j.jamcollsurg.2012.10.003. Epub 2012 Nov 21.
  12. Hutter MM, Schirmer BD, Jones DB, et al; First report from the American College of Surgeons Bariatric Surgery Center Network: laparoscopic sleeve gastrectomy has morbidity and effectiveness positioned between the band and the bypass. Ann Surg. 2011 Sep;254(3):410-20; discussion 420-2. doi: 10.1097/SLA.0b013e31822c9dac.
  13. Anthone GJ, Lord RV, DeMeester TR, et al; The duodenal switch operation for the treatment of morbid obesity. Ann Surg. 2003 Oct;238(4):618-27; discussion 627-8.
  14. Abell TL, Minocha A, Abidi N; Looking to the future: electrical stimulation for obesity. Am J Med Sci. 2006 Apr;331(4):226-32.
  15. Familiari P, Boskoski I, Marchese M, et al; Endoscopic treatment of obesity. Expert Rev Gastroenterol Hepatol. 2011 Dec;5(6):689-701. doi: 10.1586/egh.11.77.
  16. Sjostrom L; Review of the key results from the Swedish Obese Subjects (SOS) trial - a prospective controlled intervention study of bariatric surgery. J Intern Med. 2013 Mar;273(3):219-34. doi: 10.1111/joim.12012. Epub 2013 Feb 8.
  17. Vrieze A, Holleman F, Zoetendal EG, et al; The environment within: how gut microbiota may influence metabolism and body composition. Diabetologia. 2010 Apr;53(4):606-13. doi: 10.1007/s00125-010-1662-7. Epub 2010 Jan 26.
  18. Tai CM, Huang CK, Hwang JC, et al; Improvement of nonalcoholic fatty liver disease after bariatric surgery in morbidly obese Chinese patients. Obes Surg. 2012 Jul;22(7):1016-21. doi: 10.1007/s11695-011-0579-7.
  19. Bariatric Surgery; West Penn Allegheny Health System, 2013
  20. Stroh C, Birk D, Flade-Kuthe R, et al; Evidence of thromboembolism prophylaxis in bariatric surgery-results of a quality assurance trial in bariatric surgery in Germany from 2005 to 2007 and review of the literature. Obes Surg. 2009 Jul;19(7):928-36. doi: 10.1007/s11695-009-9838-2. Epub 2009 May 5.
  21. Kim JH, Wolfe B; Bariatric/metabolic surgery: short- and long-term safety. Curr Atheroscler Rep. 2012 Dec;14(6):597-605. doi: 10.1007/s11883-012-0287-3.
  22. Eid I, Birch DW, Sharma AM, et al; Complications associated with adjustable gastric banding for morbid obesity: a surgeon's guides. Can J Surg. 2011 Feb;54(1):61-6.
  23. Odom J, Zalesin KC, Washington TL, et al; Behavioral Predictors of Weight Regain after Bariatric Surgery. Obes Surg. 2009 Jun 25.
  24. Peterhansel C, Petroff D, Klinitzke G, et al; Risk of completed suicide after bariatric surgery: a systematic review. Obes Rev. 2013 Jan 9. doi: 10.1111/obr.12014.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Naomi Hartree
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Peer Reviewer:
Prof Cathy Jackson
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