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Surgical management of severe obesity in adolescents

Last literature review version 17.3: September 2009  |  This topic last updated: January 14, 2009   (More)

INTRODUCTION — During the past few years, severe obesity has gained recognition as a significant health problem facing a large proportion of adults and children in the United States [1,2]. Due to a lack of nonsurgical options for extremely obese adolescents and a demonstrated safety and efficacy record in adults, there has been increasing interest in surgical procedures for weight loss ("bariatric surgery") for selected obese adolescents with severe obesity.

The rationale, outcomes, and indications for weight loss surgery in adolescents will be reviewed here. The management and outcomes of weight loss surgery in adults and other aspects of obesity in children and adolescents are discussed separately. (See "Surgical management of severe obesity" and "Medical management of patients after bariatric surgery" and "Clinical evaluation of the obese child and adolescent" and "Comorbidities and complications of obesity in children and adolescents" and "Definition; epidemiology; and etiology of obesity in children and adolescents".)

RATIONALE — Children and adolescents with severe obesity are at risk for important comorbidities, including obstructive sleep apnea, diabetes, hypertension, cardiac hypertrophy, and nonalcoholic steatohepatitis, as well as depression and impaired quality of life [3-6]. Therefore, treatment that is targeted at obesity may treat or prevent these problems and improve long-term health outcomes. (See "Comorbidities and complications of obesity in children and adolescents".)

History of weight loss surgery — During the past 30 to 40 years, weight loss surgery has clearly been shown to produce significant and sustained reductions in BMI, diabetes, and hypertriglyceridemia in adults. It also reduces mortality, as highlighted in a 10-year follow-up of patients undergoing gastric bypass, banding, or vertical gastroplasty in the Swedish Obesity Study [7,8]. (See "Surgical management of severe obesity".)

Weight loss surgery has been performed in small groups of adolescents since the late 1970s. A recent analysis of representative national hospital administrative data from the United States demonstrated that between 1996 and 2000, the annual number of surgical weight loss procedures in adolescents remained stable [9]. However, between 2000 to 2003, the rate of surgical weight loss procedures in adolescents tripled to an estimated 771 procedures nationwide [9]. In a survey of bariatric surgeons in the United States in 2005, 75 percent indicated they were planning to perform an adolescent procedure in the upcoming year, and 42 percent were in the process of developing a multi-disciplinary adolescent weight loss surgery program in their community [10]. Nonetheless, weight loss surgery for adolescents remains a small percentage of overall annual weight loss surgery procedures in the United States (0.7 percent), with the majority of these cases (90 percent) being gastric bypass [11].

Defining severe obesity — When evaluating the risks and benefits of surgery, an important step is to identify the group of patients that are most likely to benefit from the intervention. In adults, severe obesity is generally defined as a body mass index (BMI) ≥40 kg/m2. This is also the BMI threshold for consideration of surgery as proposed by an NIH consensus panel; a threshold of 35 kg/m2 is used for adults with significant current comorbidities such as diabetes [12]. (See "Surgical management of severe obesity".)

In children, a BMI ≥99th percentile for age and gender defines a group that is at high risk for medical complications of obesity in the long term [13]. This percentile definition is based on the BMI standards defined by the CDC rather than on the actual population distribution; thus, in the United States, approximately 4 percent of children 5 to 17 years of age are currently in this range [14]. These children will almost always remain in the obese range as adults, and 65 percent will have severe obesity as adults (BMI>40) [14]. These children have a significantly greater prevalence of cardiovascular risk factors as compared with children with lesser degrees of obesity, and will have more health complications and higher mortality as compared with those who developed obesity during adulthood [15-17].

For boys, the 99th percentile for BMI is approximately 32 kg/m2 at 13 years of age and rises to 34 at 16 years of age. For girls, the 99th percentile for BMI is approximately 34 at 13 years of age, rises to 36 kg/m2 at age 15, and 38 by age 16. Therefore, use of an absolute BMI >35 will define a subgroup of patients with a degree of obesity that is even more severe than that defined by the 99th percentile for all adolescent boys, and is particularly conservative for younger adolescents. A few girls over age 14 may have a BMI>35 but not above the 99th percentile for their age. A BMI>40 will define a subgroup of patients with very severe obesity, and is above the 99th percentile for virtually all adolescents.

Z-scores provide an alternative method of defining severe obesity in children and adolescents. Z-scores correspond directly to percentiles. As an example, the 95th percentile corresponds to a z-score of 1.65, the 97th percentile to a z-score of 1.89, and the 99th percentile to a z-score of 2.33. However, z-scores beyond the 97th percentile have been calculated using mathematical equations derived from population-based data between the 3rd and 97th percentile due to insufficient numbers of subjects with BMI values greater than the 97th percentile in national samples. For this reason, actual BMI values can vary widely at percentiles above the 99th percentile. BMI percentiles and z-scores can be determined using a gender-specific calculator for boys (calculator 1) or for girls (calculator 2).

Further work is needed to correlate these different cutpoints to current and future risks of clinical comorbidities and, thereby, to the potential benefits and risks of surgery.

Alternatives — Because of the potential risks of surgical weight loss, non-invasive approaches should always be the first-line treatment for any child or adolescent with obesity. The best established approaches are multidisciplinary, using family-based behavioral techniques to support changes in diet and physical activity, with goals of reducing caloric intake, improving the quality of the food intake, and increasing energy expenditure [13]. Recommendations from an expert committee, endorsed by the American Academy of Pediatrics and other professional organizations, advocate a staged approach to weight management based on the child's degree of obesity and response to previous interventions [13,18].

Unfortunately, the limited data available suggest that dietary and behavioral interventions alone rarely achieve long-term success for individuals with severe obesity. In one study of 24 preadolescent children with severe obesity (mean BMI 34 kg/m2, ages 8 to 12) weight loss during a 12-week behavioral program was modest; children lost an average of 2.5 kg (3.2 percent) of their initial weight [19]. At follow-up seven months later, all lost weight had been regained. In another study of 12 adolescents with BMI values ≥40 kg/m2 (mean BMI 47 kg/m2) participating in a pediatric behavioral weight loss treatment program, the subjects had only a 3 percent reduction of BMI (mean 46 kg/m2) after one year [20]. Finally, obese adolescents randomized to placebo and behavioral therapy (eg, controls in pharmaceutical studies for weight loss) have typically demonstrated <3 percent weight loss [21,22]. These studies suggest that dietary and behavioral interventions generally have poor success rates for adolescents with severe obesity.

TYPES OF SURGERIES — Currently, the most widely performed procedures in adolescents and adults are the roux-en-Y gastric bypass and adjustable gastric banding (AGB). Although the gastric bypass remains the most commonly performed weight loss procedure for all age groups in the United States, the laparoscopically placed, adjustable gastric band is increasingly accepted by adults undergoing weight loss surgery. (See "Surgical management of severe obesity", section on 'Types of bariatric procedures'.)

The Food and Drug Association (FDA) has approved two adjustable gastric band devices for use in adults in the United States. The adjustable gastric band is not yet FDA-approved for adolescents younger than age 18, but an industry-sponsored prospective study is in progress, and numerous retrospective studies of adolescents have been published with favorable results (see below).

In the past, the range of surgical weight loss procedures performed on adults and a few adolescents included jejunoileal bypass (a procedure associated with a high rate of malabsorptive complications), vertical banded gastroplasty, and banded gastric bypass. Due to unsatisfactory safety profiles and/or efficacy, these procedures no longer recommended. Other procedures that cause malabsorption, such as biliopancreatic diversion, are occasionally performed on adults but are generally not recommended for adolescents due to lack of safety data in this age group and concerns about long-term nutritional complications.

MECHANISMS OF WEIGHT LOSS — Reduction of caloric intake plays an important role in the dramatic weight loss produced by bariatric surgery. However, this may not be purely due to reduced capacity of the stomach or "pouch". Many patients report a subjective decrease in appetite and increase in postprandial satiety after surgery, which helps them maintain lower intake of food. This experience suggests that the effects of bariatric surgery on weight loss and comorbidities may have neuroendocrine mechanisms, and are not due to mechanical restriction of food intake or of malabsorption.

Emerging data suggest that alterations in neuro-enteric hormones that regulate appetite and energy expenditure could contribute to changes in satiety after surgery. Several studies have demonstrated an increase in postprandial total peptide YY (both PYY and PYY3-36) after roux-en-Y gastric bypass compared with lean or obese nonoperative controls [23,24]. This post-prandial increase in PYY is not reported after an adjustable gastric band [25,26]. However, a single series of 12 patients undergoing the vertical banded gastroplasty (also purely restrictive) reported an increase in fasting and postprandial PYY after surgery to levels comparable to those measured in lean controls [27].

Dramatic improvements in insulin resistance and diabetes occur after gastric bypass, even prior to any significant weight loss. These changes may in part be due to increased secretion of incretins, such as glucagon-like-peptide-1 (GLP-1) by intestinal endocrine cells after surgery. After gastric bypass, postprandial GLP-1 plasma levels rise dramatically as compared to levels in lean and obese controls, and as compared to patients undergoing adjustable gastric banding [26]. Further research is needed to elucidate the mechanisms through which bariatric surgery causes this abrupt enhancement of insulin sensitivity.

OUTCOMES

Weight loss — Virtually all studies reporting outcomes of weight loss surgery in adolescents have utilized a retrospective design and report short- to intermediate-term outcomes (outcomes measured from 1 to 6.3 years after surgery). A few studies have reported small numbers of patients 10 or more years after their procedure. In most of these long-term studies, a substantial number of subjects were lost to follow-up, which could bias findings.

Despite these limitations, the existing retrospective data clearly demonstrate that both bypass and banding in adolescents lead to clinically important and durable decreases in weight and BMI in the majority of patients. The largest retrospective series of adolescents after gastric bypass reported a 37 percent overall reduction in BMI at one year postoperatively [20]. Weight loss outcomes are often reported as percentage of excess weight loss (EWL). Several series have reported 56 to 62 percent EWL after roux-en-Y gastric bypass [28,29]. Comparable results have been reported after adjustable gastric banding in adolescents. In two studies of adolescents undergoing adjustable gastric banding, mean weight loss after ranged from 52 to 60 percent EWL at one- and two-years follow-up [30-32]. Importantly, the rate of weight loss appears to be more gradual after adjustable gastric banding, with maximal weight loss only achieved at 12 or more months after surgery [30,31]. One study reported a remarkable outcome of 70 percent EWL (range 37 to 101 percent) in 18 patients followed for three years after adjustable gastric banding [33].

Weight loss after surgery is accompanied by a significant reduction in body fat (from 51 percent to 37 percent in one series) with a relative preservation of lean body mass [34]. Not surprisingly, given the improvement in adiposity, obesity-related diseases usually improve or resolve after surgically induced weight loss in adolescents. The most dramatic improvements have been seen in insulin resistance, triglyceride levels, diabetes, obstructive sleep apnea, as well as depression and quality of life [4,20,33,35,36]. One study also showed improvements in obesity-associated cardiac abnormalities, including concentric left ventricular hypertrophy and diastolic function, as measured by echocardiogram performed before and 10 ± 3 months after gastric bypass surgery [37].

It is not clear to what degree weight loss will be sustained in adolescents and whether comorbid conditions will recur if significant weight is regained in long-term follow-up. Two studies with 4 to 10 years of follow-up suggest that 10 to 15 percent of patients regain significant weight after gastric bypass procedures [28,38]. A substantial number of patients also regain some or all of their lost weight after adjustable gastric banding. In one retrospective series of 24 adolescents, maximal EWL (52 percent) occurred at one year after adjustable gastric banding with a regression to 42 percent EWL at two and three years [31]. Specific predictors of weight regain after surgical weight loss procedures are unknown for adults and adolescents. There is still insufficient information to directly compare the long-term weight loss outcomes of roux-en-Y gastric bypass to those for adjustable gastric banding in adolescents.

Short-term complications — Perioperative complications (<30 days) are generally similar to those in adults. Complications after gastric bypass include intestinal leakage at anastomotic sites, wound infections, pulmonary embolus, gastrojejunal strictures requiring endoscopic dilatation, small bowel obstruction, gastrogastric fistula formation, and symptomatic cholelithiasis [29]. Complications of adjustable banding procedures in adolescents and adults include band slippage requiring repositioning, gastric obstruction, and esophageal or gastric pouch dilatation [31]. (See "Complications of bariatric surgery".)

Several studies performed in the United States suggest weight loss surgery may be somewhat safer in adolescents as compared with adults. The reason for this is unknown, but the observation may reflect a better state of health among individuals undergoing surgery at a young age.

  • A national analysis of weight loss surgery using utilization codes revealed no perioperative mortality and a significantly shorter length of stay in adolescents as compared with adults [9]. Five percent of adolescent patients had major complications, but the majority (78.3 percent) were respiratory in nature.
  • A large study comparing the perioperative outcomes of weight loss surgery between 309 adolescents and 55,192 adults (>18 years) found that the overall 30-day complication rate was significantly lower in adolescents (5.5 percent) as compared to adults (9.8 percent). There was no difference in observed/expected mortality ratios. The 30-day morbidity and mortality rates for adolescents following restrictive procedures (adjustable gastric banding and gastroplasty) were nil, in comparison with the morbidity rate of 4.3 percent for laparascopic gastric bypass, and 7.6 percent for open gastric bypass [39].

Long-term complications — Long-term complications of weight loss surgery in adolescents are primarily nutritional. In particular, patients are at risk for deficiency of iron, vitamin B12, vitamin D, and thiamine. For this reason, life-long vitamin and mineral supplementation is imperative. However, adherence to supplementation regimens among adolescents may be poor; one study reported that only 13 percent of adolescents were adherent to all prescribed nutritional supplementation [28,38]. The specific recommendations are outlined below. (See 'Nutritional supplements' below.)

Some adult patients have developed severe postprandial hypoglycemia after gastric bypass [40,41]. The exact cause of these hypoglycemic episodes is not known but may result in part from increased incretin secretion after surgery, pancreatic islet cell hyperplasia, and inappropriate postprandial hyperinsulinemia [42]. Although a similar syndrome in adolescents after gastric bypass has not yet been reported in the literature, at least one adolescent patient in the authors' weight loss surgery program developed severe postprandial hyperinsulinemia after gastric bypass. Dietary management by providing small meals with relatively low content of carbohydrates was successful in controlling symptoms. Therefore, it is important to query adolescents seen in follow-up about symptoms that may suggest postprandial hypoglycemia.

Long-term follow-up of adjustable gastric banding in adult patients indicates that reoperations due to complications, including slippage, erosion, or device failure, occurs in 10 to 32 percent of adults [43,44]. One prospective evaluation of adults undergoing adjustable gastric banding in Sweden indicated that one-third of the 196 patients experienced a major reoperation: 18 percent had a band replacement and 14 percent had removal [44]. Late complications included band migration, leakage, slippage, and pouch dilatation, as well as device-related problems, such as tube replacement and port-related complications. The long-term outcome of adjustable gastric banding in adolescents is unknown and prospective data on the rate of complications and device removal must be collected.

PREOPERATIVE EVALUATION AND SCREENING

Screening — Recommended screening prior to surgical weight loss procedures includes evaluation for the presence and severity of coexisting diseases, as well as assessment of the patient's and family's understanding and readiness for a life-changing and often permanent procedure. The table highlights the recommended screening tests and evaluations that should be completed during the evaluation (table 1). The final decision on whether to proceed with surgery must be made by the multidisciplinary team, taking into consideration both objective and subjective assessments of the patient's severity of obesity and related diseases, risk of future health problems, failure to lose weight through more conventional means, psychosocial status and support, and patient and family readiness for surgery.

A multidisciplinary approach is recommended when offering weight loss surgery to extremely obese adolescents [45-47]. At a minimum, the team evaluating and caring for the candidate should include an experienced bariatric surgeon, pediatric obesity specialist, nurse, dietician, and pediatric psychologist or psychiatrist. One of these providers or an additional team member should have responsibility for coordinating each patient's care and ensuring follow-up and adherence to the prescribed medical regimen. The program also must have ready access to relevant pediatric subspecialties, including endocrinology, cardiology, gastroenterology, pulmonology, gynecology, and orthopedics for further evaluation and/or management of specific comorbidities as needed.

Patient selection — In adults, the threshold for consideration of weight loss surgery is a BMI ≥40 kg/m2; a threshold of 35 kg/m2 is used for individuals with significant current comorbidities, such as diabetes.

In adolescents, BMI percentile curves increase with age and vary by gender. This creates some difficulty using a flat threshold for BMI during a period of continued linear growth and applied to both genders. The use of a flat BMI cutpoint as a minimum threshold for consideration of weight loss surgery has the advantage of being more conservative at younger ages (ie, corresponding to a higher BMI percentile or z-score). However, it also underestimates the severity of obesity in younger male adolescents (ages 13 to 17) in which a BMI of 40 corresponds to a BMI percentile significantly greatly than the 99th percentile. Therefore, as more information becomes available about the outcomes of weight loss surgery in adolescents, as well as the natural history and distribution of severe obesity in adolescents, it is possible that an age-specific threshold (percentile or z-score) will become more appropriate than a flat BMI threshold.

Current z-scores corresponding to BMI values above the 97th percentile have been calculated using mathematical equations derived from the population data used to generate the 3rd to 97th percentiles. Therefore, extrapolation of percentiles and z-scores beyond the 97th percentile must be done cautiously due to the potential wide variability around the percentile lines. (See 'Defining severe obesity' above.)

The most widely accepted BMI criteria for weight loss surgery in adolescents include a BMI ≥40 kg/m2 with one or more significant obesity-related disorders (eg, type 2 diabetes mellitus, obstructive sleep apnea, pseudotumor cerebri, or severe steatohepatitis), or a BMI of ≥50 with more minor comorbidities (hypertension, dyslipidemia, mild steatohepatitis, significant impairment in quality of life, or arthropathy) [45,47,48].

However, because of mounting evidence of the adverse long-term consequences of severe adolescent obesity, and favorable safety outcomes of surgery in adolescents, a panel of pediatric obesity and bariatric surgery experts has recommended modifying these criteria. The proposed new criteria include the following [49]:

  • BMI ≥35 kg/m2 and a severe comorbidity that has significant short-term effects on health, such as severe obstructive sleep apnea, diabetes mellitus type 2, pseudotumor cerebri or severe and progressive steatohepatitis, OR BMI≥40 with more minor comorbidities.
  • Physical maturity, defined as completing 95 percent of predicted adult stature based on bone age or reaching Tanner stage IV. (This criterion may not be necessary for adjustable gastric banding procedures because weight loss is usually more gradual).
  • History of sustained efforts to lose weight through changes in diet and physical activity. There is no evidence that prolonged preoperative weight management programs enhance selection of patients for weight loss surgery. However, consistent attendance in such a treatment program may be a valuable indicator of the patient's ability to understand and adhere to medical and nutritional recommendations postoperatively.

It should be recognized that the above criteria alone are not sufficient to select the patients who are most likely to benefit from weight loss surgery during adolescence. We recommend that the multidisciplinary team consider carefully whether the patient and family have the ability and motivation to adhere to recommended treatments pre- and post-operatively, including consistent use of micronutrient supplements. Evidence may include a history of reliable attendance at office visits for weight management and compliance with other medical needs. In addition, the team should consider whether the adolescent shows evidence of mature decision-making, with appropriate understanding of the risks and benefits of surgery, and has support but not coercion from family members.

Contraindications for surgical weight loss procedures in adolescents include:

  • Medically correctable cause of obesity
  • An ongoing substance abuse problem (within the preceding year)
  • A medical, psychiatric, psychosocial, or cognitive condition that prevents adherence to post-operative dietary and medication regimens or impairs decisional capacity
  • Current or planned pregnancy within 12 to 18 months of the procedure
  • Inability on the part of the patient or parent to comprehend the risks and benefits of the surgical procedure

The risks and benefits of weight loss surgery for individuals with syndromic obesity (eg, Prader-Willi syndrome) have not been adequately explored, and more investigation is required before use of surgery can be widely recommended [50]. It is unclear whether weight loss surgery is effective for these individuals, and they may have increased risks for complications, such as gastric rupture. (See "Clinical features, diagnosis, and treatment of Prader-Willi syndrome".)

PERIOPERATIVE SAFETY — To provide for optimum safety of the patient while hospitalized, it is important to ensure that the program also has access to pediatric anesthesiology and radiology consultants who have experience caring for individuals with severe obesity. Specialized equipment, such as CT, MRI, and DEXA scanners, often have weight limitations, which may preclude their use for these patients [51]. Further, basic equipment such as operating tables, stretchers, scales, beds, and toilets that can support extreme weight ranges must be available to ensure safety of the patient and caretakers.

To prevent the development of venous thromboembolism, we recommend the use of compression boots until the patient is ambulatory. Patients at increased risk for deep vein thrombosis and thromboembolism (eg, those with severely impaired mobility or a hypercoagulable state) are often treated with low-molecular weight heparin in the perioperative period. (See "Complications of bariatric surgery", section on 'Pulmonary embolus' and "Management of the critically ill bariatric patient", section on 'Venous thromboembolism'.)

Weight loss surgery frequently leads to an abrupt resolution of hypertension and hyperglycemia. Antihypertensive or hypoglycemic medications that were given preoperatively usually can be discontinued after surgery, and the patient should be monitored for their response. (See "Medical management of patients after bariatric surgery", section on 'Medication management'.)

POSTOPERATIVE MANAGEMENT — Average inpatient stays range from three to four days for laparoscopic roux-en-y gastric bypass and from one to two days for laparoscopic adjustable gastric banding. Postoperative management for patients includes strict measurement of intake and output, monitoring of drain output (after roux-en-y gastric bypass) to evaluate for potential leak, and gradual advancement of diet from NPO to clear liquids to a high-protein liquid diet. (See "Medical management of patients after bariatric surgery", section on 'Nutritional management and food intolerance'.)

Diet — Dietary management after discharge varies with the type of surgery. After roux-en-y gastric bypass, the patient advances through several stages, from high-protein shakes to gradual introduction of greater volumes and more textured and solid foods. The advancement to regular foods is slow, occurring over the first six months after surgery. For best results, the patient is encouraged to eat three to four small, high-protein meals per day and to avoid high-fat and carbohydrate foods, as these may provoke malabsorptive or dumping side effects. Supplemental fluids are encouraged to avoid dehydration (64 to 92 ounces per day of sugar-free, noncarbonated beverages). Drinks should be sugar-free to avoid dumping syndrome and weight regain through over-consumption of liquid calories. Patients also are advised to avoid drinking during meals to avoid nausea and vomiting.

After adjustable gastric banding, patients are able to return to a regular diet more quickly. The tightness of the band is sequentially adjusted (every four to six weeks during the first one to two years) to maintain satiety and restrict food intake. If large volumes of food are eaten quickly, vomiting may result, which may provide an additional incentive to limit intake. Three to four small meals are recommended, again with high-protein content, to maintain lean body mass during the weight loss. The patient gradually learns to feel sated with smaller volumes of meals and to chew more slowly. As compared with roux-en-y gastric bypass, weight loss after gastric banding is slower and more gradual, although ultimate weight loss appears to be comparable. Excessive tightening of the band may result in recurrent vomiting, which in turn can lead to nutritional deficiencies, such as beriberi or long-term maladaptive eating behaviors.

Follow-up visits for gastric bypass patients are typically performed at two weeks postoperatively, then 1, 3, 6, 9, and 12 months after surgery. After that, annual follow-up is recommended for monitoring of anthropometric measurements, nutritional status, residual comorbidities, and general health. Follow-up for banding patients typically is more frequent due to the need for band adjustments. Some patients require visits every four to six weeks during the first one to two years.

General recommendations for long-term weight maintenance include:

  • Drinking 8 to 12 eight-ounce servings of sugar-free liquids per day
  • Exercising 30 to 60 minutes daily
  • Eating protein first at each meal (1 gm/kg of ideal body weight)
  • Three to four portion-controlled meals per day, with minimal snacking between meals
  • Taking daily vitamin and mineral supplementation

These guidelines may need to be tailored to meet an individual patient's needs if significant weight regain or too much weight loss has occurred.

Nutritional supplements — After gastric bypass or banding procedures, life-long supplementation with vitamins and minerals is recommended to avoid development of nutritional complications secondary to reduced intake and/or mild malabsorption.

After roux-en-y gastric bypass, patients should conscientiously adhere to a supplementation regimen because of risks for malabsorption of micronutrients; the recommended doses and preparations vary somewhat among practices and may be adjusted based on laboratory measures.

We prescribe the following supplements for all patients (table 2):

  • Standard multivitamin with folate and iron, or prenatal vitamin if female
  • Vitamin B12, 500 micrograms orally daily
  • Calcium, 1200 to 1500 mg daily (measured as elemental calcium), with 800 mg vitamin D

Additional supplementation may be necessary during pregnancy or as indicated by laboratory testing. If postoperative vomiting is severe, vitamin B1 deficiency also can rapidly develop. Vitamin B1 is particularly important to recognize early, as lasting neurologic sequelae can result if rapid replenishment of vitamin B1 is not initiated [52]. In the author's program, vitamin B1 supplementation is provided during the first six months after surgery as a prophylactic measure.

After adjustable gastric banding, a routine multivitamin may suffice if a well-balanced, healthy diet is consumed. However, menstruating females may require additional iron supplementation, and all patients should have routine monitoring for deficiencies as described below.

Nutritional monitoring — After bariatric surgery, life-long monitoring of nutritional status is recommended. In our practice, we measure the following parameters annually:

  • Complete blood cell count with differential
  • Serum iron and ferritin
  • Red blood cell folate, serum vitamin B12, and serum homocysteine
  • Albumin and total protein
  • Alkaline phosphatase, calcium, vitamin D, and parathyroid hormone
  • DEXA to monitor lean and fat-free mass, and bone density (this test is optional and may not be needed annually or for patients with good nutritional status)

Adjustments in nutritional supplements may need to be made if specific deficiencies emerge over time, particularly because many adolescents may be nonadherent or only partially adherent to recommended supplementation. (See "Medical management of patients after bariatric surgery", section on 'Micronutrient deficiency'.)

Pregnancy prevention — Severe obesity can lead to irregular menstruation, anovulation, and infertility. Conversely, surgically induced weight loss leads to resumption of ovulation and renewed fertility for some women [53]. The effects of bariatric surgery on menstrual irregularities and anovulation in adolescents has not been established. However, in a series of 47 adolescent females who had undergone bariatric surgery during adolescence, a higher-than-expected rate of pregnancy was observed (seven pregnancies, six of which occurred between 10 and 22 months postoperatively) [54]. Though the medical and psychosocial factors contributing to this high rate could not be addressed in this retrospective report, the high rate of pregnancy highlights the importance of addressing contraception and pregnancy prevention in all female adolescents undergoing bariatric surgery. Pregnancy should absolutely be avoided for the first year after surgery due to the rapid weight loss and potential micronutrient deficiencies, which may have adverse effects on the mother and fetus. However, long-term effects of bariatric surgery on fertility and pregnancy outcomes are generally good. (See "Medical management of patients after bariatric surgery", section on 'Pregnancy'.)

The efficacy of oral contraceptives or transdermal contraceptive patches may be compromised in patients with obesity [55-57]. This is a significant concern both pre- and postoperatively, as many adolescent patients may still have a postoperative BMI >30kg/m2 despite significant weight loss after surgery. Further, use of oral contraception is associated with an increased risk of thromboembolism, which may compound the higher risk associated with obesity. For this reason, we suggest avoiding oral contraceptives during the first six months after surgery.

Depot medroxyprogesterone acetate is effective in overweight or obese women but has been reported to cause significant weight gain (mean of 4 to 9 kg) in overweight or obese adolescents [58,59]. In contrast, the levonorgestrel intrauterine system (Mirena, Bayer Schering Pharma, Berlin, Germany) does not cause weight gain and remains effective in overweight/obese women [60]. It has several notable advantages that make it an optimal choice for adolescent females after bariatric surgery, including five-year efficacy, promotion of amenorrhea (which could help reduce risk of iron deficiency anemia after surgery), and option for placement at time of bariatric surgery [61]. However, as with all forms of hormonal contraception, adolescents should be counseled to use additional barrier protection against sexually transmitted diseases.

Adolescent females who become pregnant after weight loss surgery should be counseled about adequate macro- and micronutrient intake. At a minimum, a prenatal vitamin with folic acid and iron, 1200 to 1500 mg of calcium citrate with 800 IU vitamin D, and 500 mcg of oral vitamin B12 daily should be prescribed [62]. Additional iron supplementation may be necessary in pregnant women after gastric bypass. Iron, folate, and vitamin B12 levels should be monitored during pregnancy and additional supplementation prescribed as indicated by results. Protein intake of at least 1 gm/kg of ideal body weight (typically 60 to 80 grams) per day is recommended.

SUMMARY AND RECOMMENDATIONS — Surgical weight loss is an appropriate consideration for adolescents with severe obesity and with medical comorbidities who have failed to lose weight through conventional dietary interventions and behavioral modification.

  • The most widely performed procedures in adolescents and adults are the roux-en-Y gastric bypass (RYGB) and adjustable gastric banding (AGB). Other procedures that cause significant malabsorption are generally not recommended for adolescents due to lack of safety data in this age group and concerns about long-term nutritional complications. (See 'Types of surgeries' above.)

Outcomes

  • There appear to be substantial clinical benefits of weight loss surgery for selected adolescents with severe obesity and medical comorbidities. This statement is based on retrospective studies with outcomes measured less than 10 years postoperatively, and the characteristics of patients included in these studies varies widely. (See 'Outcomes' above.)

  • Reported weight loss for adolescents undergoing weight loss surgery ranges from 52 to 70 percent of excess body weight. In most cases, there are associated improvements in adiposity, insulin resistance, triglyceride levels, diabetes, obstructive sleep apnea, depression, and impaired quality of life. These outcomes are comparable to those reported for adults undergoing weight loss surgery. The rate of weight loss appears to be more gradual after adjustable gastric banding as compared to gastric bypass. (See 'Weight loss' above.)

  • Perioperative complications in adolescents undergoing weight loss surgery are generally similar to those in adults but occur somewhat less frequently. Long-term complications are primarily nutritional and include deficiencies of iron, vitamin B12, vitamin D, and thiamine. Life-long vitamin and mineral supplementation is imperative. However, adherence to supplementation regimens among adolescents may be poor. (See 'Outcomes' above.)

Patient selection

  • Weight loss surgery for adolescents should be performed in the context of a multidisciplinary program with specific expertise in adolescent medicine and extensive expertise in bariatric surgery. (See 'Screening' above.)

  • We suggest using a BMI of ≥35 kg/m2 as a minimum threshold for consideration of weight loss surgery in an adolescent with significant medical comorbidities (Grade 2C). This is a lower BMI threshold than that proposed in earlier guidelines because emerging data show potential advantages of earlier surgery and good safety outcomes as compared to adults. (See 'Patient selection' above.)

  • Other important criteria for patient selection include physical maturity, lack of medically correctable causes of obesity, and adequate emotional maturity and stability to ensure competent decision-making and good adherence to medical follow-up (table 1). In addition, most authorities agree that the patient should have failed organized and sustained attempts to lose weight through lifestyle intervention. (See 'Patient selection' above.)

Management

  • Perioperative and postoperative management is similar to that for adults undergoing weight loss surgery. Diet recommendations vary depending on the type of procedure and vary slightly among centers. (See 'Perioperative safety' above and 'Diet' above.)

  • We recommend avoidance of pregnancy for 12 to 18 months after surgical weight loss procedures (Grade 2B). Because adolescent girls appear to be at high risk for pregnancy after gastric bypass surgery as compared to others in their age group, all girls should have counseling about pregnancy avoidance and assurance of adequate contraception as part of the preparation and follow up after weight loss surgery. (See 'Pregnancy prevention' above.)

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