Bariatric Surgery

Obesity occurs as the result of an imbalance between energy expenditure and caloric intake. This imbalance has been thought to be under genetic and environmental influence. The discovery of immunologic abnormalities in obesity that are related to the leptin-proopiomelanocortin system and elevated tumor necrosis factor alpha (TNF-α) brought a new perspective to the understanding of obesity.

Leptin (from Greek leptos, "thin") is a hormone made primarily in adipocytes. The circulating leptin levels reflect the amount of stored body fat. Leptin is a negative feedback signal that acts on the hypothalamus to alter the expression of several neuroendocrine peptides that regulate energy intake and expenditure. Central resistance to leptin is a prominent feature of obesity.

Increased leptin levels in individuals who are obese are independent of the lipid profile but strongly correlate with the BMI. Leptin exhibits direct effects on monocytes that results in secretion of the interleukin (IL)-1 receptor antagonist (IL-1RA). This cytokine antagonist has anti-inflammatory properties. Although leptin treatment works very well in patients who are leptin-deficient, the use of leptin in patients who are obese and who already have high levels of leptin has shown limited efficacy.

Obesity is a complex, multifactorial chronic disease influenced by the interaction of several factors, such as genetic, endocrine, metabolic, environmental (social and cultural), behavioral, and psychological components. The basic mechanism involves energy intake that exceeds energy output.

The number of overweight individuals in the world has been estimated at 1.7 billion. In the United States, the problem is at epidemic proportions. As much as two thirds of the population in the United States is overweight, and half of the people in this group can be classified as obese.

The Swedish Obese Subjects (SOS) study is an ongoing, prospective study of 2010 obese participants who underwent bariatric surgery and 2037 obese patients who received usual care in the primary health care system. Compared to the control group, obese adults who underwent surgery experienced a reduced number of cardiovascular deaths and a lower incidence of heart attack and stroke.[1, 2]  A 2017 report from the SOS group found that bariatric surgery reduced the long-term incidence of female-specific cancer, particularly endometrial cancer.[3]

Low back pain is a common complaint among obese patients. A retrospective study of morbidly obese patients who underwent bariatric surgery found that patients experienced a significant decrease in low back and radicular pain after surgery, which led to improvements in quality of life. Patients also experienced a marked increase in the L4-5 intervertebral disc height.[4]

An Australian study by Keating et al compared the results of weight-loss treatments in patients who had been diagnosed with type 2 diabetes mellitus in class I/II obesity, estimating the lifetime costs and quality-adjusted life-years (QALYs) for individuals who had undergone surgically induced weight loss and for patients who had utilized conventional weight loss treatment.[5]

In this study, the mean duration of diabetes remission over a lifetime was 11.4 years in the surgical therapy group and 2.1 years in the conventional therapy group.[5] Over the remainder of their lifetime, surgical therapy patients lived 15.7 discounted QALYs, compared with 14.5 discounted QALYs for conventional therapy patients. Mean discounted lifetime costs were AUD $98,900 per surgical therapy patient and AUD $101,400 per conventional therapy patient (AUD $1 = USD $0.74). Compared with conventional therapy, surgical therapy yielded a mean healthcare saving of AUD $2400 and 1.2 additional QALYs per patient.

In another study, Keating et al looked at the within-trial cost efficacy, over 2 years, of surgical treatment relative to that of conventional therapy for achieving remission in patients recently diagnosed with type 2 diabetes mellitus with class I/II obesity.[6]  Trial intervention costs included gastric banding surgery, mitigation of complications, outpatient medical consultations, medical investigations, pathology, weight-loss therapies, and medication.

An incremental cost-effectiveness analysis demonstrated that the mean 2-year intervention costs per patient were Au $13,400 for surgical therapy and Au $3400 for conventional therapy; laparoscopic adjustable gastric band (LAGB) surgery was responsible for 85% of the difference.[6] For surgical patients, outpatient medical consultation costs were threefold greater than those for conventional patients, but medication costs were 1.5 times higher for patients who underwent conventional therapy. The cost differences occurred primarily in the trial's first 6 months. In relation to conventional treatment, the incremental cost-effectiveness ratio for surgical therapy was Au $16,600 per case of diabetes remitted.

An updated Cochrane review from 2014 that included 22 trials with 1798 participants concluded that surgical treatment of obesity yielded greater improvement in weight loss and weight-associated comorbidities than nonsurgical interventions did, regardless of the type of procedure,[7]  though certain procedures were associated with greater weight loss and fewer comorbidities than others.

In this review, Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy had comparable outcomes, and both had better outcomes than adjustable gastric banding.[7]  In very-high-BMI patients, biliopancreatic diversion with duodenal switch yielded better weight loss than RYGB did. Outcomes were comparable for duodenojejunal bypass with sleeve gastrectomy and laparoscopic RYGB. Isolated sleeve gastrectomy led to better weight loss than adjustable gastric banding. Weight-related outcomes were similar for laparoscopic gastric imbrication and laparoscopic sleeve gastrectomy.

In general, with all 22 studies taken into account, rates of adverse events and reoperation were not well reported.[7]  Because the follow-up period in most of the trials reviewed was only 1 or 2 years, the long-term effects of bariatric surgery could not be definitively established.

A study by Jakobsen et al assessed obesity-related comorbidities in 1888 severely obese patients undergoing either bariatric surgery (n = 932; 92 gastric bypass) or specialized medical treatment (n = 956).[8]  Median follow-up was 6.5 years (range, 0.2-10.1 years). Surgical patients were more likely to experience remission and diabetes remission and were less likely to experience new-onset hypertension; however, they also had a greater risk of new-onset depression and treatment with opioids and were more likely to undergo at least one additional GI surgical procedure.

Ikramuddin et al evaluated lifestyle intervention and medical management with (n = 60) and without RYGB (n = 60) for achieving control of type 2 diabetes (composite triple end point: HbA1c < 7.0%, LDL cholesterol < 100 mg/dL, systolic blood pressure < 130 mm Hg).[9]  Of the 120 patients, 98 completed 5-year follow-up. At 5 years, there remained a significantly better composite triple end point in the surgical group; however, the effect size diminished over 5 years, indicating the need for further follow-up to better define the durability of the improvement.

Morbid obesity is the harbinger of many other diseases that affect essentially every organ system, including the following:

• Cardiovascular (eg, hypertension, atherosclerotic heart and peripheral vascular disease with myocardial infarction and cerebral vascular accidents, peripheral venous insufficiency, thrombophlebitis, pulmonary embolism)
• Respiratory (eg, asthma, obstructive sleep apnea, obesity-hypoventilation syndrome)
• Metabolic (eg, type 2 diabetes, impaired glucose tolerance, hyperlipidemia)
• Musculoskeletal (eg, back strain; disc disease; weightbearing osteoarthritis of the hips, knees, ankles, and feet)
• Gastrointestinal (eg,  cholelithiasis,  gastroesophageal reflux disease, nonalcoholic fatty liver disease [steatosis steatohepatitis], hepatic cirrhosis, hepatic carcinoma, colorectal carcinoma)
• Urologic (eg, stress incontinence)
• Endocrine and reproductive (eg, polycystic ovary syndrome, increased risk of pregnancy and fetal abnormalities, male hypogonadism)
• Cancer of the endometrium, breast, ovary, prostate, and pancreas
• Dermatologic (eg, intertriginous dermatitis)
• Neurologic (eg,  pseudotumor cerebri, carpal tunnel syndrome)
• Psychologic (eg, depression, eating disorders, body image disturbance)

Preoperative laboratory evaluation should include the following:

• Complete blood count (CBC)
• Complete chemistry panel
• Liver function tests
• Thyroid function tests
• Lipid profile
• Coagulation tests
• Serum iron and total iron binding capacity (TIBC)
• Vitamin B12
• Folic acid
• Blood typing
• Urinalysis

Imaging studies to be considered in the setting of bariatric surgery include the following:

• Chest radiography
• Ultrasonography (US) of the gallbladder

Upper gastrointestinal (GI) endoscopy is performed to rule out intrinsic upper GI disease because after gastric bypass surgery, nonsurgical visualization of the distal stomach and the duodenum could prove challenging.

Surgery for obesity should be considered as a treatment of last resort after dieting, exercise, psychotherapy, and drug treatments have failed.

Since the 1991 National Institutes of Health (NIH) Consensus Development Conference Panel, the generally accepted criteria for surgical treatment have included a body mass index (BMI) higher than 40 kg/m2 or a BMI higher than 35 kg/m2 in combination with high-risk comorbid conditions, such as sleep apnea, pickwickian syndrome, diabetes mellitus, or degenerative joint disease.

In 2022, however, the American Society of Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) issued updated indications for metabolic and bariatric surgery that included all individuals with BMIs of 35 kg/m2 or greater, as well as selected individuals with lower BMIs (see Guidelines).[10]

Guidelines have also been developed for the use of bariatric surgery in pediatric patients and patients with type 2 diabetes mellitus (see Guidelines).[11, 12]

Contraindications for bariatric surgery include illnesses that greatly reduce life expectancy and are unlikely to be improved with weight reduction, including advanced cancer and end-stage renal, hepatic, and cardiopulmonary disease. Conditions that may render patients unable to understand the nature of bariatric surgery or the behavioral changes required afterward, including untreated schizophrenia, active substance abuse, and noncompliance with previous medical care, are also considered contraindications for bariatric surgery.

Favorable outcomes of bariatric surgery can lead to socioeconomic advancement, which may require patient guidance. Postoperative care may also include planning for reconstructive operations after weight stabilization for certain patients.

A preoperative trial of weight loss is beneficial to ensure patient compliance with the postoperative diet protocol. Also, a preoperative liquid diet can shrink the liver, thus facilitating the surgical procedure.

Surgical options

Types of bariatric surgery include the following:

• Restrictive procedures (eg, adjustable gastric banding, sleeve gastrectomy)
• Restrictive procedures with some malabsorption (eg, Roux-en-Y gastric bypass)
• Malabsorptive procedures with some restriction (eg, biliopancreatic diversion with duodenal switch)

Bariatric surgery can be performed either via an open approach or via a laparoscopic approach. The laparoscopic approach has become the more popular one.

Preoperative considerations

The diversity of clinical and occult obesity-related comorbidities necessitates a multidisciplinary team approach in the preoperative evaluation of the patient who is morbidly obese. This evaluation will enhance the postoperative outcome. Preoperative cardiac, pulmonary, psychiatric, and endocrine evaluations may be necessary. These evaluations help to exclude patients who may not benefit from surgery; at the same time, they optimize those considered being potential good candidates for surgery. Preoperative nutritional consultation helps in obtaining a detailed diet history and in explaining preoperative and postoperative diet protocol.

Gastric bypass

Gastric bypass is currently the most popular procedure performed in the United States. (See the image below.) This procedure has earned the reputation of being the gold standard, against which other procedures are compared. The procedure has a restrictive and a malabsorptive component.

The gastric bypass provides a substantial amount of dietary restriction. The restriction is created by the small stomach pouch, which gives the patient a feeling of satiety after eating a small meal. The restrictive element of the operation consists of the creation of a small gastric pouch (approximately 20 mL in volume) and probably a small outlet that, on distention by food, causes the sensation of satiety.

In addition, the gastric bypass provides a small-to-moderate degree of intentional malabsorption due to the separation of food, which passes through the alimentary limb of the Y, from the biliopancreatic secretions, which pass through the biliopancreatic limb of the Y. The degree of malabsorption can be adjusted by modifying the length of the alimentary and biliopancreatic limbs.

The malabsorptive element is a result of bypassing the distal stomach, the entire duodenum, and varying the length of the jejunum. The extent of the bypass of the intestine determines the degree of macronutrient malabsorption. The standard Roux limb is about 75 cm. More extensive malabsorptive variations consist of gastric bypasses with a 150-cm Roux limb (long-limb) or with a very long-limb (distal gastric bypass). In addition to restricting food intake, causing some degree of malabsorption, it also causes dumping syndrome in response to a high-sugar liquid meal.

Weight loss after a standard 75-cm Roux gastric bypass usually exceeds 100 lb or about 65-70% of excess body weight and about 35% of BMI. The longer-limb bypasses are used to obtain comparable weight reductions in patients who are super obese (BMI >50 kg/m2). Weight loss generally levels off in 1-2 years, and a regain of up to 20 lb from the weight loss nadir to a long-term plateau is common.

Reversal

For all bariatric procedures, pure reversal without conversion to another bariatric procedure is almost certainly followed by a return to morbid obesity. Gastric bypass can be reversed, though this is rarely required.

Revision

A standard Roux gastric bypass with failed weight loss can be revised to a very-long-limb Roux-en-Y procedure (see the image below), or the dilated gastric pouch can be revised.

Results

After gastric bypass surgery, some patients may experience dumping syndrome upon ingestion of sweets. This is caused by the rapid passage of gastric pouch contents directly into the small bowel, unimpeded by a pyloric valve. The presence of concentrated simple sugars in the Roux limb presents a substantial osmotic load that may result in cramping and abdominal discomfort; additionally, the ensuing rapid release of insulin by the pancreas may cause symptomatic hypoglycemia. This unpleasant reaction to sugar is considered to be a desired effect of gastric bypass surgery, and it has been referred to by patients as the postoperative police officer.

Weight loss after gastric bypass has been shown to be greater than that obtained by dietary, medical, behavioral, or combined approaches to weight loss.

A long-term follow-up study performed by MacLean et al defined postoperative success as a reduction in weight to a BMI of less than 35 kg/m2.[13] By this criterion, a successful outcome was achieved in 93% of patients with an initial BMI of less than 50 kg/m2 and in 57% of patients with an initial BMI of greater than 50 kg/m2.

Since its initial description in 1994 by Wittgrove et al, laparoscopic gastric bypass has been shown to combine the efficacy of the open approach with the decreased pain, lower wound morbidity, and shorter convalescence of a minimally invasive procedure.[14] Results of several laparoscopic gastric bypass series have paralleled or improved upon those of open surgery.

In Higa's series of 400 laparoscopic procedures, patients lost an average of 69% of their initial excess weight by 12 months after the procedure.[15] Schauer's group reported even better weight loss; a group of 275 patients undergoing laparoscopic gastric bypass lost an average of 83% of excess weight at 24 months after surgery.

A prospective, randomized trial was completed that compared the results of laparoscopic gastric bypass to the results of open gastric bypass. Patients who had undergone laparoscopic gastric bypass were found to have substantially less impairment of pulmonary function after surgery and decreased postoperative pain.

In the author's experience, convalescence after laparoscopic gastric bypass is substantially reduced relative to open procedures, with some patients returning to work in 2 weeks or less.

Laparoscopic adjustable gastric banding

Laparoscopic adjustable gastric banding is the most common bariatric procedure and is performed in Europe, Australia, and South America. (See the image below.) Currently, two devices are approved by the US Food and Drug Administration (FDA) for this use in the United States: the Lap-Band (Apollo Endosurgery, Austin, TX) and the Realize Band (Ethicon Endo-Surgery, Somerville, NJ).

In this procedure, an adjustable inflatable band is placed around the proximal part of the stomach. This creates a small gastric pouch (~15 mL in volume) and a small stoma. Band restriction is adjustable by adding or removing saline from the inflatable band by a reservoir system of saline attached to the band and accessible through a port, which is attached by a catheter to the band. The port is placed subcutaneously in the anterior abdominal wall after the band is secured around the stomach.

Adjustment of the band through the access port is an essential part of laparoscopic adjustable gastric banding therapy. Appropriate adjustments, performed as often as six times annually, are critical for successful outcomes. Patients must chew food thoroughly to allow food to pass through the band. Adjusting the inflation of the cuff changes the size of the opening through which food passes but does not change the size of the gastric pouch; deflation of the cuff is useful when the outlet is obstructed.

Weight loss after laparoscopic adjustable gastric banding is about 50-60% of excess body weight in approximately 2 years.

Laparoscopic adjustable gastric banding can be completely reversed with removal of the band, tubing, and port.

Combining laparoscopic adjustable gastric banding with gastric plication may improve weight-loss outcomes, at least in the short term.[16]

Biliopancreatic diversion with duodenal switch

Biliopancreatic diversion with duodenal switch (see the image below) includes the following:

• Lateral 75% gastrectomy, resulting in a tubular stomach
• Duodenum divided past the pyloric valve
• Ileum divided
• Distal end anastomosed to proximal duodenum
• Common channel created distally with Y-anastomosis
• Optional appendectomy and cholecystectomy

Malabsorption is achieved by separating food from biliopancreatic digestive fluids. More weight loss results from fat malabsorption. Protein absorption is also reduced. This has the best weight loss with the least regain. There is less disruption of eating patterns. Early weight loss is from restriction and malabsorption, and, later, it is mostly from malabsorption; 75-85% of excess body weight loss is at 18 months. Pyloric preservation protects against marginal ulceration and dumping syndrome.

The procedure is technically challenging and difficult to reverse. Insurance companies may not cover this procedure, because it is still considered investigational.

Laparoscopic sleeve gastrectomy

Laparoscopic sleeve gastrectomy (LSG), a type of unbanded gastroplasty, employs subtotal gastric resection to create a long lesser curvature–based gastric conduit. (See the image below.)

In this procedure, the stomach is reduced to about 15-20% of its original size by the surgical removal of a large portion of the stomach, following the greater curve. The mechanism of weight loss and resultant comorbidity improvement that follows sleeve gastrectomy may be related to gastric restriction or to neurohumoral changes observed following the procedure (due to the gastric resection).

Sleeve gastrectomy has been used as the first stage of a two-stage procedure for high-risk patients,[17] but owing to its simplicity and favorable outcomes,[18] it is currently being offered as a standalone primary procedure. In the first decade of the 21st century, many hundreds of sleeve gastrectomies were performed in the United States. On the basis of follow-up periods of 6 months to 3 years, patients were found to have lost 33-83% of their excess weight.[19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32]

Compared with other bariatric procedures, sleeve gastrectomy is the more physiologic treatment because it does not involve malabsorption, abnormal tracts, blind tracts, or the placement of a foreign body. This procedure is widely performed laparoscopically.[31]

Hutter et all conducted the first large, prospective, multi-institutional study comparing 1-year outcomes of LSG to other procedures. Results show LSG has morbidity and effectiveness between laparoscopic adjustable gastric banding and standard Roux bypass.[33]

As with other bariatric procedures that involve stomach transection, the main drawback of sleeve gastrectomy is the severity of postoperative complications. The use of staple-line reinforcement was shown to be associated with improved perioperative outcomes and can be considered as an effective method for preventing leaks.[34]

A larger prospective comparative study involving 187 patients undergoing laparoscopic sleeve gastrectomy found that reinforcement of the staple line with bovine pericardium strips was associated with a significant reduction in bleeding from the staple line and intra-abdominal collections, whereas the leak rate was not significantly reduced. It is unclear, though, whether controlling for high BMI, previous bariatric surgery, and diabetes was taken into account.[35]

In a randomized study that involved 120 patients who had undergone laparoscopic sleeve gastrectomy, using either polyglycolide acid with tri-methylene carbonate or gelatin fibrinmatrix for SLR was found to be faster as compared with oversewing, whereas no significant differences in postoperative complications were observed between the three methods.[36]

According to two studies presented at Obesity Week 2017, LSG is safer than laparoscopic gastric bypass at 30 days (though both procedures are very safe); however, in the longer term (7 years and beyond), one quarter to one third of LSG patients may require a revision or regain lost weight.[37]

Incision reduction strategies

There has been a growing trend in bariatric surgery toward reduction of abdominal incisions, a change offering much-improved cosmetic outcomes and, potentially, shorter patient hospital stays. (See the image below.)

Such minimally invasive surgery also provides, as a result of decreased abdominal trauma, reductions in pain, scarring, and tissue injury. Saber et al developed a single-incision transumbilical laparoscopic approach for sleeve gastrectomies, in which the procedure is performed mainly through the umbilicus; the sleeve is extracted through the umbilicus without extending the incision.[31, 38]

In addition, Saber et al developed a single-incision transumbilical laparoscopic technique for the placement of an adjustable gastric band; in addition to offering the aforementioned benefits of such an approach, this technique facilitates later outpatient adjustment of the band.[39, 40]

After surgery, patients must remain on a high-protein, low-fat diet, and they must supplement their diet with multivitamins, iron, and calcium, usually on a twice-daily basis. Ursodiol may be given to minimize the risk of developing gallstones during the period of acute weight loss. Patients must modify their eating habits by avoiding chewy meats and other foods that may inhibit normal emptying of their stomach pouch.

Nutritional and metabolic blood tests must be performed on a frequent basis; in the author's practice, these tests are performed at 6 months after surgery, 12 months after surgery, and then annually thereafter.

Postoperative body contouring

Massive weight loss is associated with negative consequences for the body, such as flabby skin, abdominal skin overhang, and pendulous breasts. The excess skin does not regain the tightness it had before the weight gain. Redundant rolls of tissue may also be associated with intertrigo and significant hygiene problems. Surgical correction of these body deformities can significantly enhance physical and physiologic changes. The usual time lapse between gastric bypass and plastic surgery procedures is 12-18 months.

Treatment alternatives for body contouring procedures are as follows:

• Lipoplasty
• Conventional surgery
• Combination of the two procedures

Conventional contouring procedures include abdominoplasty, buttock lift, lower body lift, thigh lift, upper arm lift, facelift, breast reduction, mastopexy, and augmentation. Multiple procedures are usually required, and a staged approach to body contouring surgery following bariatric surgery seems to improve safety and outcomes.

Complications of body contouring procedures include hematomas and seromas, as well as fat necrosis, skin slough, infection, and deep vein thrombosis (DVT). In addition, the patient should be involved with a team that assesses nutritional and psychological issues as needed.[41]

Gastric bypass

Early complications of Roux-en-Y gastric bypass are as follows:

• Anastomotic leak (1-3%)
• Pulmonary embolism, DVT (< 1%)
• Wound infection (more common with open approach)
• Gastrointestinal hemorrhage, bleeding (0.5-2%)
• Respiratory insufficiency, pneumonia
• Acute distention of the distal stomach

Late complications (less frequent and less dramatic than with gastric banding) of the Roux-en-Y procedure are as follows:

• Stomal stenosis, most common (20%)
• Bowel obstruction, small bowel obstruction (1%)
• Internal hernia
• Cholelithiasis
• Micronutrient deficiencies
• Marginal ulcer
• Staple line disruption
• Ventral hernia formation (more prevalent after open approach)

Although there is a statistical increase in the number of patients needing cholecystectomy after obesity surgery, the number is small enough to prevent suggesting a prophylactic procedure at the time of their bariatric surgery.[42]

In a large study (N = 42,345) that included a substantial population of older adults, Yu et al found that Roux-en-Y gastric bypass (n = 29,624) was associated with a 73% increased risk of nonvertebral (eg, hip, wrist, and pelvis) fracture after the procedure as compared with adjustable gastric banding (n = 12,721).[43] The difference in postoperative fracture risk between the two procedures was consistent across different subgroups and occurred to a similar degree among older and younger adults.

Risk factors associated with an increased risk of postoperative morbidity include the following[44] :

• Recent myocardial infarction/angina
• Stroke
• Bleeding disorder
• Hypertension
• Higher BMI

Operative (30-day) mortality for gastric bypass when performed by skilled surgeons is about 0.5%. The risk of dying in the first month after a Roux-en-Y gastric bypass from complications of the operation is about 0.2-0.5% in expert centers. Studies have demonstrated that the mortality reported by hospitals with less experience with the procedure is far higher than that reported by expert centers. Compared with open procedures, laparoscopic gastric bypass has a higher rate of intra-abdominal complications, whereas the duration of hospitalization is shorter, wound complications are lower, and the postoperative patient comfort is higher.[45]

Lifelong oral or intramuscular vitamin B12 supplementation and iron, vitamin B, folate, and calcium supplementation are recommended to avoid specific nutrient deficiency conditions, such as anemia.

Adjustable gastric banding

Early complications of the adjustable gastric band procedure are as follows:

• Injury of the stomach or esophagus
• Bleeding
• Food intolerance (most common immediate postoperative complication)
• Wound infection
• Pneumonia

Late complications are as follows:

• Food intolerance or noncompliance to band (13%)
• Band slippage (stomach prolapse) (2.2-8%)
• Pouch dilatation
• Band erosion into the stomach
• Port complications
• Reoperation rate (2-41%)
• Esophageal dilatation
• Failure to lose weight
• Port infection, band infection
• Leakage of the balloon or tubing
• Mortality (0.5%; 0% in some series)

Biliopancreatic diversion with duodenal switch

Because the biliopancreatic diversion with duodenal switch procedure is less well known, the complications are potentially more problematic if the surgeon is unfamiliar with the procedure.

Fat malabsorption results in diarrhea and foul-smelling gas in approximately 30% of patients.

The potential nutritional deficiencies mandate frequent follow-up visits, with close monitoring and supplementation of multivitamins and minerals.

• Malabsorption of fat soluble vitamins (vitamins A, D, E, and K)
• Vitamin A deficiency, which causes night blindness
• Vitamin D deficiency, which causes osteoporosis
• Iron deficiency (similar incidence to Roux-en-Y gastric bypass procedure)
• Protein-energy malnutrition (may require a second operation to lengthen the common channel)

In a case series and national database study, Ungaro et al found bariatric surgery to be associated with an increased risk of new-onset inflammatory bowel disease.[46]

Care of the postoperative bariatric surgery patient is recommended for the lifetime of the patient, with at least three follow-up visits with the bariatric surgery team within the first year. Laparoscopic adjustable gastric banding requires more frequent visits for band adjustment. Postoperative dietary changes (including vitamin, mineral, and possibly liquid protein supplementation), exercise, and lifestyle changes should be reinforced by counseling, support groups, and the patient's family physician.

In November 2022, the American Society of Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) issued updates to the 1991 National Institutes of Health (NIH) guidelines for bariatric surgery.[10] Recommendations included the following:

• Metabolic and bariatric surgery (MBS) is recommended for all individuals with a body mass index (BMI) higher than 35 kg/m ², regardless of the presence, absence, or severity of comorbid conditions.
• MBS should be considered for individuals who have metabolic disease and a BMI between 30 and 34.9 kg/m ².
• In the Asian population, BMI thresholds should be adjusted so that a BMI exceeding 25 kg/m ² suggests clinical obesity. MBS should be offered to Asian individuals with BMIs higher than 27.5 kg/m ².
• Long-term results of MBS consistently demonstrate safety and efficacy.
• MBS should be considered for appropriately selected children and adolescents.

 

In June 2016, the 2nd Diabetes Surgery Summit (DSS-II), an international consensus conference, issued the following global guidelines regarding the benefits and limitations of bariatric/metabolic surgery for type 2 diabetes mellitus[12] :

• Metabolic surgery should be a  recommended option to treat type 2 diabetes mellitus in appropriate surgical candidates with class III obesity (BMI ≥40 kg/m ²), regardless of the level of glycemic control or complexity of glucose-lowering regimens, as well as in patients with class II obesity (BMI 35.0-39.9 kg/m ²) with inadequately controlled hyperglycemia despite lifestyle and optimal medical therapy
• Metabolic surgery should also be  considered to be an option to treat type 2 diabetes in patients with class I obesity (BMI 30.0-34.9 kg/m ²) and inadequately controlled hyperglycemia despite optimal medical treatment by either oral or injectable medications (including insulin)
• All BMI thresholds should be reconsidered depending on the ancestry of the patient; for example, for patients of Asian descent, the BMI values above should be reduced by 2.5 kg/m ²
• Metabolic surgery should be performed in high-volume centers with multidisciplinary teams that understand and are experienced in the management of diabetes and gastrointestinal surgery
• Ongoing and long-term monitoring of micronutrient status, nutritional supplementation, and support must be provided to patients after surgery, according to guidelines for postoperative management of bariatric/metabolic surgery by national and international professional societies
• Metabolic surgery is a potentially cost-effective treatment option in obese patients with type 2 diabetes; the clinical community should work together with health care regulators to recognize metabolic surgery as an appropriate intervention for type 2 diabetes in people with obesity and to introduce appropriate reimbursement policies

In January 2015, the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) published a position statement on bariatric surgery for severely obese children and adolescents, which provided the following guidelines[11] :

• Consider bariatric surgery in "carefully selected" patients with a body mass index (BMI) higher than 40 kg/m ² who have severe comorbidities (eg, nonalcoholic fatty liver disease [NAFLD]) or in those with a BMI higher than 50 kg/m ² who have milder comorbidities
• Additional factors to consider in deciding whether a child or adolescent should undergo bariatric surgery include physical and psychological maturity, personal desire to undergo the procedure, previous attempts at weight loss, and ability to adhere to follow-up care
• Roux-en-Y gastric bypass, laparoscopic adjustable gastric banding, and sleeve gastrectomy are the most widely used procedures in pediatric obesity, but their use is associated with subsequent nutritional deficiencies; temporary intragastric devices could represent a better option for initial treatment in pediatric populations
• Current evidence suggests that bariatric surgery can decrease the grade of steatosis, hepatic inflammation, and fibrosis in NAFLD
• Uncomplicated NAFLD is not an indication for bariatric surgery
• Roux-en-Y gastric bypass is considered a safe and effective option for extremely obese adolescents, as long as appropriate long-term follow-up is provided
• Laparoscopic adjustable gastric banding has not been approved by the FDA for use in adolescents and therefore should be considered investigational
• Sleeve gastrectomy and other types of weight loss surgery that have grown increasingly common in adults must still be considered investigational