Bariatric surgery (weight loss surgery) includes a variety of procedures performed on people who have obesity. Weight loss is achieved by reducing the size of the stomach with a gastric band or through removal of a portion of the stomach (sleeve gastrectomy or biliopancreatic diversion with duodenal switch) or by resecting and re-routing the small intestine to a small stomach pouch (gastric bypass surgery).
Long-term studies show the procedures cause significant long-term loss of weight, recovery from diabetes, improvement in cardiovascular risk factors, and a reduction in mortality of 23% from 40%. However, a study in Veterans Affairs (VA) patients has found no survival benefit associated with bariatric surgery among older, severely obese people when compared with usual care, at least out to seven years.
The U.S. National Institutes of Health recommends bariatric surgery for obese people with a body mass index (BMI) of at least 40, and for people with BMI of at least 35 and serious coexisting medical conditions such as diabetes. However, research is emerging that suggests bariatric surgery could be appropriate for those with a BMI of 35 to 40 with no comorbidities or a BMI of 30 to 35 with significant comorbidities. The most recent ASMBS guidelines suggest the position statement on consensus for BMI as an indication for bariatric surgery. The recent guidelines suggest that any patient with a BMI of more than 30 with comorbidities is a candidate for bariatric surgery.
- 1 Indications
- 2 Classification of surgical procedures
- 2.1 Predominantly malabsorptive procedures
- 2.2 Predominantly restrictive procedures
- 2.3 Mixed procedures
- 3 Eating after bariatric surgery
- 4 Effectiveness of surgery
- 5 Costs of surgery
- 6 Adverse effects
- 7 Bariatric surgery in youth
- 8 History
- 9 See also
- 10 References
- "Surgery should be considered as a treatment option for patients with a BMI of 40 kg/m2 or greater who instituted but failed an adequate exercise and diet program (with or without adjunctive drug therapy) and who present with obesity-related comorbid conditions, such as hypertension, impaired glucose tolerance, diabetes mellitus, hyperlipidemia, and obstructive sleep apnea. A doctor–patient discussion of surgical options should include the long-term side effects, such as a possible need for reoperation, gallbladder disease, and malabsorption."[not in citation given]
- "Patients should be referred to high-volume centers with surgeons experienced in bariatric surgery."
In 2011, the International Diabetes Federation issued a position statement suggesting "Under some circumstances, people with a BMI 30–35 should be eligible for surgery." When determining eligibility for bariatric surgery for extremely obese patients, psychiatric screening is critical; it is also critical for determining postoperative success. Patients with a body-mass index of 40 kg/m2 or greater have a 5-fold risk of depression, and half of bariatric surgery candidates are depressed.
Classification of surgical procedures
Procedures can be grouped in three main categories: Standard of care in the United States and most of the industrialized world in 2009 is for laparoscopic as opposed to open procedures. Future trends are attempting to achieve similar or better results via endoscopic procedures.
Predominantly malabsorptive procedures
In predominantly malabsorptive procedures, although they also reduce stomach size, the effectiveness of these procedures is derived mainly from creating a physiological condition of malabsorption.
This complex operation is termed biliopancreatic diversion (BPD) or the Scopinaro procedure. The original form of this procedure is now rarely performed because of problems with malnourishment. It has been replaced with a modification known as duodenal switch (BPD/DS). Part of the stomach is resected, creating a smaller stomach (however the patient can eat a free diet as there is no restrictive component). The distal part of the small intestine is then connected to the pouch, bypassing the duodenum and jejunum.
In around 2% of patients there is severe malabsorption and nutritional deficiency that requires restoration of the normal absorption. The malabsorptive effect of BPD is so potent that those who undergo the procedure must take vitamin and dietary minerals above and beyond that of the normal population. Without these supplements, there is risk of serious deficiency diseases such as anemia and osteoporosis.
Because gallstones are a common complication of the rapid weight loss following any type of bariatric surgery, some surgeons remove the gallbladder as a preventive measure during BPD. Others prefer to prescribe medications to reduce the risk of post-operative gallstones.
Far fewer surgeons perform BPD compared to other weight loss surgeries, in part because of the need for long-term nutritional follow-up and monitoring of BPD patients.
This procedure is no longer performed. It was a surgical weight-loss procedure performed for the relief of morbid obesity from the 1950s through the 1970s in which all but 30 cm (12 in) to 45 cm (18 in) of the small bowel was detached and set to the side.
A study on humans was done in Chile using the same technique  however the results were not conclusive and the device had issues with migration and slipping. A study recently done in the Netherlands found a decrease of 5.5 BMI points in 3 months with an endoluminal sleeve.
Predominantly restrictive procedures
Procedures that are solely restrictive act to reduce oral intake by limiting gastric volume, produce early satiety, and leave the alimentary canal in continuity, minimizing the risks of metabolic complications. 
Vertical banded gastroplasty
In the vertical banded gastroplasty, also called the Mason procedure or stomach stapling, a part of the stomach is permanently stapled to create a smaller pre-stomach pouch, which serves as the new stomach.
Adjustable gastric band
The restriction of the stomach also can be created using a silicone band, which can be adjusted by addition or removal of saline through a port placed just under the skin. This operation can be performed laparoscopically, and is commonly referred to as a "lap band". Weight loss is predominantly due to the restriction of nutrient intake that is created by the small gastric pouch and the narrow outlet.  It is considered one of the safest procedures performed today with a mortality rate of 0.05%. 
Sleeve gastrectomy, or gastric sleeve, is a surgical weight-loss procedure in which the stomach is reduced to about 15% of its original size, by surgical removal of a large portion of the stomach, following the major curve. The open edges are then attached together (typically with surgical staples, sutures, or both) to leave the stomach shaped more like a tube, or a sleeve, with a banana shape. The procedure permanently reduces the size of the stomach. The procedure is performed laparoscopically and is not reversible.
This combined approach has tremendously decreased the risk of weight loss surgery for specific groups of patients, even when the risk of the two surgeries is added. Most patients can expect to lose 30 to 50% of their excess body weight over a 6–12 month period with the sleeve gastrectomy alone. The timing of the second procedure will vary according to the degree of weight loss, typically 6 – 18 months.
- Stomach volume is reduced, but it tends to function normally so most food items can be consumed in small amounts.
- Removes the portion of the stomach that produces the hormone that stimulates hunger (Ghrelin), although the durability of this removal has yet to be confirmed.
- Dumping syndrome is less likely due to the preservation of the pylorus (although dumping can occur any time stomach surgery takes place).
- Minimizes the chance of an ulcer occurring.
- By avoiding the intestinal bypass, the chance of intestinal obstruction (blockage), anemia, osteoporosis, protein deficiency and vitamin deficiency are significantly reduced.
- Very effective as a first stage procedure for high BMI patients (BMI >55 kg/m2).
- Limited results appear promising as a single stage procedure for low BMI patients (BMI 35–45 kg/m2).
- Appealing option for people with existing anemia, Crohn's disease, irritable bowel syndrome, and numerous other conditions that make them too high risk for intestinal bypass procedures.
Intragastric balloon (gastric balloon)
Intragastric balloon involves placing a deflated balloon into the stomach, and then filling it to decrease the amount of gastric space. The balloon can be left in the stomach for a maximum of 6 months and results in an average weight loss of 5–9 BMI over half a year. The intragastric balloon is approved in Australia, Canada, Mexico, India, United States (received FDA approval in 2015) and several European and South American countries. The intragastric balloon may be used prior to another bariatric surgery in order to assist the patient to reach a weight which is suitable for surgery, further it can also be used on several occasions if necessary.
There are three cost categories for the intragastric balloon: pre-operative (e.g. professional fees, lab work and testing), the procedure itself (e.g. surgeon, surgical assistant, anesthesia and hospital fees) and post-operative (e.g. follow-up physician office visits, vitamins and supplements).
Quoted costs for the intragastric balloon are surgeon-specific and vary by region. Average quoted costs by region are as follows (provided in United States Dollars for comparison): Australia: $4,178 USD; Canada: $8,250 USD; Mexico: $5,800 USD; United Kingdom: $6,195 USD; United States: $8,150 USD).
Basically, the procedure can best be understood as a version of the more popular gastric sleeve or gastrectomy surgery where a sleeve is created by suturing rather than removing stomach tissue thus preserving its natural nutrient absorption capabilities. Gastric plication significantly reduces the volume of the patient's stomach, so smaller amounts of food provide a feeling of satiety. The procedure is producing some significant results that were published in a recent study in Bariatric Times and are based on post-operative outcomes for 66 patients (44 female) who had the gastric sleeve plication procedure between January 2007 and March 2010. Mean patient age was 34, with a mean BMI of 35. Follow-up visits for the assessment of safety and weight loss were scheduled at regular intervals in the postoperative period. No major complications were reported among the 66 patients. Weight loss outcomes are comparable to gastric bypass.
The study describes gastric sleeve plication (also referred to as gastric imbrication or laparoscopic greater curvature plication) as a restrictive technique that eliminates the complications associated with adjustable gastric banding and vertical sleeve gastrectomy—it does this by creating restriction without the use of implants and without gastric resection (cutting) and staples.
Mixed procedures apply both techniques simultaneously.
Gastric bypass surgery
A common form of gastric bypass surgery is the Roux-en-Y gastric bypass, designed to reduce the amount of food a person is able to eat by cutting away a part of the stomach, gastric bypass is a permanent procedure that helps patients by changing how the stomach and small intestine handle the food that is eaten to achieve and maintain weight loss goals. After the surgery, the stomach will be smaller. A patient will feel full with less food.
The gastric bypass had been the most commonly performed operation for weight loss in the United States, and approximately 140,000 gastric bypass procedures were performed in 2005. Its market share has decreased since then and by 2011, the frequency of gastric bypass was thought to be less than 50% of the weight loss surgery market. 
A factor in the success of any bariatric surgery is strict post-surgical adherence to a healthy pattern of eating.
There are certain patients who cannot tolerate the malabsorption and dumping syndrome associated with gastric bypass. In such patients, although earlier considered to be an irreversible procedure, there are instances where gastric bypass procedure can be partially reversed.
Sleeve gastrectomy with duodenal switch
A variation of the biliopancreatic diversion includes a duodenal switch. The part of the stomach along its greater curve is resected. The stomach is "tubulized" with a residual volume of about 150 ml. This volume reduction provides the food intake restriction component of this operation. This type of gastric resection is anatomically and functionally irreversible. The stomach is then disconnected from the duodenum and connected to the distal part of the small intestine. The duodenum and the upper part of the small intestine are reattached to the rest at about 75–100 cm from the colon.
Implantable gastric stimulation
This procedure where a device similar to a heart pacemaker is implanted by a surgeon, with the electrical leads stimulating the external surface of the stomach, is being studied in the USA. Electrical stimulation is thought to modify the activity of the enteric nervous system of the stomach, which is interpreted by the brain to give a sense of satiety, or fullness. Early evidence suggests that it is less effective than other forms of bariatric surgery.
Eating after bariatric surgery
Immediately after bariatric surgery, the patient is restricted to a clear liquid diet, which includes foods such as clear broth, diluted fruit juices or sugar-free drinks and gelatin desserts. This diet is continued until the gastrointestinal tract has recovered somewhat from the surgery. The next stage provides a blended or pureed sugar-free diet for at least two weeks. This may consist of high protein, liquid or soft foods such as protein shakes, soft meats, and dairy products. Foods high in carbohydrates are usually avoided when possible during the initial weight loss period.
Post-surgery, overeating is curbed because exceeding the capacity of the stomach causes nausea and vomiting. Diet restrictions after recovery from surgery depend in part on the type of surgery. Many patients will need to take a daily multivitamin pill for life to compensate for reduced absorption of essential nutrients. Because patients cannot eat a large quantity of food, physicians typically recommend a diet that is relatively high in protein and low in fats and alcohol.
It is very common, within the first month post-surgery, for a patient to undergo volume depletion and dehydration. Patients have difficulty drinking the appropriate amount of fluids as they adapt to their new gastric volume. Limitations on oral fluid intake, reduced calorie intake, and a higher incidence of vomiting and diarrhea are all factors that have a significant contribution to dehydration. In order to prevent fluid volume depletion and dehydration, a minimum of 48–64 fl oz should be consumed by repetitive small sips all day.
Effectiveness of surgery
In general, the malabsorptive procedures lead to more weight loss than the restrictive procedures; however, they have a higher risk profile. A meta-analysis from University of California, Los Angeles, reports the following weight loss at 36 months:
- Biliopancreatic diversion — 117 Lbs / 53 kg
- Roux-en-Y gastric bypass (RYGB) — 90 Lbs / 41 kg
- Open — 95 Lbs/ 43 kg
- Laparoscopic — 84 Lbs / 38 kg
- Vertical banded gastroplasty — 71 Lbs / 32 kg
The maximum weight loss occurs in the first 10 months after surgery. More recent studies have demonstrated that the medium (3–8 years) and long term (> 10 years) weight loss results for RYGB and LAGB become very similar. However, the range of excess weight loss for LAGB patients (25% to 80%) is much broader than that of RYGB patients (50% to 70%). Data (beyond 5 years) for sleeve gastrectomy indicates weight loss statistics similar to RYGB.
Reduced mortality and morbidity
In the short term, weight loss from bariatric surgeries is associated with reductions in some comorbidities of obesity, such as diabetes, metabolic syndrome and sleep apnea, but the benefit for hypertension is uncertain. It is uncertain whether any given bariatric procedure is more effective than another in controlling comorbidities. There is no high quality evidence concerning longer-term effects compared with conventional treatment on comorbidities.
Bariatric surgery in older patients has also been a topic of debate, centered on concerns for safety in this population; the relative benefits and risks in this population is not known.
Given the remarkable rate of diabetes remission with bariatric surgery, there is considerable interest in offering this intervention to people with type 2 diabetes who have a lower BMI than is generally required for bariatric surgery, but high quality evidence is lacking and optimal timing of the procedure is uncertain.
Laparoscopic bariatric surgery requires a hospital stay of only one or two days. Short-term complications from laparoscopic adjustable gastric banding are reported to be lower than laparoscopic Roux-en-Y surgery, and complications from laparoscopic Roux-en-Y surgery are lower than conventional (open) Roux-en-Y surgery.
Some studies have suggested that psychological health can improve after bariatric surgery.
Costs of surgery
The costs of bariatric surgery depend on the type of procedure performed and method of payment along with location-specific factors including geographical region, surgical practice and the hospital in which the surgery is performed.
The four established procedure types (Roux-en-Y gastric bypass, gastric banding, vertical sleeve gastrectomy (gastric sleeve) and duodenal switch) carry an average cost in the United States of $24,000, $15,000, $19,000 and $27,000 respectively. However, costs can vary significantly by location. Quoted costs generally include fees for the hospital, surgeon, surgical assistant, anesthesia and implanted devices (if applicable). Depending on the surgical practice, costs may include or omit pre-op, post-op or longer-term follow-up office visits.
Complications from weight loss surgery are frequent. A study of insurance claims of 2522 who had undergone bariatric surgery showed 21.9% complications during the initial hospital stay and a total of 40% risk of complications in the subsequent six months. This was more common in those over 40 and led to an increased health care expenditure. Common problems were gastric dumping syndrome in about 20% (bloating and diarrhea after eating, necessitating small meals or medication), leaks at the surgical site (12%), incisional hernia (7%), infections (6%) and pneumonia (4%) where the mortality was 0.2%. As the rate of complications appears to be reduced when the procedure is performed by an experienced surgeon, guidelines recommend that surgery be performed in dedicated or experienced units. It has been observed that the rate of leaks was greater in low volume centres whereas high volume centres showed a lesser leak rate. Leak rates have now globally decreased to a mean of 1-5%.
Metabolic bone disease manifesting as osteopenia and secondary hyperparathyroidism have been reported after Roux-en-Y gastric bypass surgery due to reduced calcium absorption. The highest concentration of calcium transporters is in the duodenum. Since the ingested food will not pass through the duodenum after a bypass procedure, calcium levels in the blood may decrease, causing secondary hyperparathyroidism, increase in bone turnover, and a decrease in bone mass. Increased risk of fracture has also been linked to bariatric surgery.
Rapid weight loss after obesity surgery can contribute to the development of gallstones as well by increasing the lithogenicity of bile. Adverse effects on the kidneys have been studied. Hyperoxaluria that can potentially lead to oxalate nephropathy and irreversible renal failure is the most significant abnormality seen on urine chemistry studies. Rhabdomyolysis leading to acute kidney injury, and impaired renal handling of acid and base has been reported after bypass surgery.
Nutritional derangements due to deficiencies of micronutrients like iron, vitamin B12, fat soluble vitamins, thiamine, and folate are especially common after malabsorptive bariatric procedures. Seizures due to hyperinsulinemic hypoglycemia have been reported. Inappropriate insulin secretion secondary to islet cell hyperplasia, called pancreatic nesidioblastosis, might explain this syndrome.
A study published in JAMA-Surgery reports that self-harm behaviors and suicide are increased in those having bariatric surgery.
Bariatric surgery in youth
As childhood obesity has more than doubled over recent years and more than tripled in adolescents (according to the CDC), bariatric surgery for youth has become increasingly common. Some worry that a decline in life expectancy might occur from the increasing levels of obesity, so providing youth with proper care may help prevent the serious medical complications caused by obesity and its related diseases. Difficulties and ethical issues arise when making decisions related to obesity treatments for those that are too young or otherwise unable to give consent without adult guidance.
Children and adolescents are still developing, both physically and mentally. This makes it difficult for them to make an informed decision and give consent to move forward with a treatment. These patients may also be experiencing severe depression or other psychological disorders related to their obesity that make understanding the information very difficult.
Open weight loss surgery began slowly in the 1950s with the intestinal bypass. It involved anastomosis of the upper and lower intestine, which bypasses a large amount of the absorptive circuit, which caused weight loss purely by the malabsorption of food. Later Drs. J. Howard Payne, Lorent T. DeWind and Robert R. Commons developed in 1963 the Jejuno-colic Shunt, which connected the upper small intestine to the colon. The laboratory research leading to gastric bypass did not begin until 1965 when Dr. Edward E. Mason (b.1920) and Dr. Chikashi Ito (1930–2013) at the University of Iowa developed the original gastric bypass for weight reduction which led to fewer complications than the intestinal bypass and for this reason Mason is known as the "father of obesity surgery". 
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