Bariatric Surgery

To qualify for bariatric surgery, patients should

Bariatric surgery should also be considered for patients with a BMI of 30 to 34.9 with type 2 diabetes who have inadequate glycemic control despite optimal lifestyle and medical therapy (1 Indications reference Bariatric surgery is the surgical alteration of the stomach, intestine, or both to cause weight loss. In the US, about 250,000 bariatric operations are done in each year. Development of safer... read more ).

Contraindications include

The most common procedures done in the US include

Most procedures are done laparoscopically, resulting in less pain and a shorter healing time than open surgery. Traditionally, bariatric surgery has been classified as restrictive and/or malabsorptive, referring to the presumptive mechanism of weight loss. However, other factors appear to contribute to weight loss; for example, RYGB (traditionally classified as malabsorptive) and sleeve gastrectomy (traditionally classified as restrictive) both result in metabolic or hormonal changes that favor satiety and weight loss and in other hormonal changes (eg, an increase in insulin release [incretin effect]) that appear to contribute to the rapid remission of diabetes Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more .

After RYGB (particularly) or sleeve gastrectomy, levels of gastrointestinal hormones, such as glucagon-like peptide-1 (GLP-1) and peptide YY (PYY), are increased, possibly contributing to satiety, weight loss, and remission of diabetes. Increased insulin sensitivity is evident immediately postoperatively, before significant weight loss occurs, suggesting that neurohormonal factors are prominent in remission of diabetes. A change in gut microbiome may also contribute to changes in weight after RYGB. Bariatric surgery reduces mortality caused by cardiovascular diseases, diabetes, and cancer.

Preoperative evaluation consists of

Extensive preoperative evaluation is not routinely necessary, but preoperative testing may be necessary based on clinical findings, and measures to control certain conditions (eg, hypertension) or reduce risk may be taken.

Perioperative risks are lowest when bariatric surgery is done in an accredited center.

Complications include

These complications can cause significant morbidity, prolong hospitalization, and increase costs. Tachycardia may be the only early sign of anastomotic leak.

Later problems may include prolonged nausea and vomiting secondary to small-bowel obstruction Intestinal Obstruction Intestinal obstruction is significant mechanical impairment or complete arrest of the passage of contents through the intestine due to pathology that causes blockage of the bowel. Symptoms include... read more and anastomotic stenosis.

Nutritional deficiencies (eg, protein-energy undernutrition Protein-Energy Undernutrition (PEU) Protein-energy undernutrition (PEU), previously called protein-energy malnutrition, is an energy deficit due to deficiency of all macronutrients. It commonly includes deficiencies of many micronutrients... read more , vitamin B12 deficiency Vitamin B12 Deficiency Dietary vitamin B12 deficiency usually results from inadequate absorption, but deficiency can develop in vegans who do not take vitamin supplements. Deficiency causes megaloblastic anemia, damage... read more , iron deficiency Iron Deficiency Iron (Fe) is a component of hemoglobin, myoglobin, and many enzymes in the body. Heme iron is contained mainly in animal products. It is absorbed much better than nonheme iron (eg, in plants... read more ) may result from inadequate intake, inadequate supplementation, or malabsorption. Malodorous flatulence, diarrhea, or both may develop, particularly after malabsorptive procedures. Calcium and vitamin D absorption may be impaired, causing deficiencies and sometimes hypocalcemia Hypercalcemia Hypercalcemia is a total serum calcium concentration > 10.4 mg/dL (> 2.60 mmol/L) or ionized serum calcium > 5.2 mg/dL (> 1.30 mmol/L). Principal causes include hyperparathyroidism... read more and secondary hyperparathyroidism. With prolonged vomiting, thiamin deficiency Thiamin Deficiency Thiamin deficiency (causing beriberi) is most common among people subsisting on white rice or highly refined carbohydrates in countries with high rates of food insecurity and among people with... read more may occur.

Patients may have symptoms of reflux, especially after sleeve gastrectomy. During rapid weight loss, cholelithiasis Cholelithiasis Cholelithiasis is the presence of one or more calculi (gallstones) in the gallbladder. In developed countries, about 10% of adults and 20% of people > 65 years have gallstones. Gallstones... read more (often symptomatic), gout Gout Gout is a disorder caused by hyperuricemia (serum urate > 6.8 mg/dL [> 0.4 mmol/L]) that results in the precipitation of monosodium urate crystals in and around joints, most often causing recurrent... read more , and nephrolithiasis Urinary Calculi Urinary calculi are solid particles in the urinary system. They may cause pain, nausea, vomiting, hematuria, and, possibly, chills and fever due to secondary infection. Diagnosis is based on... read more may develop.

Incidence of psychologic disorders such as depression Depressive Disorders Depressive disorders are characterized by sadness severe enough or persistent enough to interfere with function and often by decreased interest or pleasure in activities. Exact cause is unknown... read more is increased in patients having bariatric surgery. A 2016 meta-analysis confirmed this increase in preoperative depression and reported a postoperative decrease in the prevalence and severity of depression (1 Risks references Bariatric surgery is the surgical alteration of the stomach, intestine, or both to cause weight loss. In the US, about 250,000 bariatric operations are done in each year. Development of safer... read more ). One large study suggested that the risk of suicide in patients who had bariatric surgery was increased compared with that in controls (2.7 versus 1.2 per 10,000 person-year; hazard ratio 1.71 [0.69 to 4.25]; P value = 0.25 [ 2 Risks references Bariatric surgery is the surgical alteration of the stomach, intestine, or both to cause weight loss. In the US, about 250,000 bariatric operations are done in each year. Development of safer... read more ]). Incidence of alcohol use disorder Alcohol Use Disorder and Rehabilitation Alcohol use disorder involves a pattern of alcohol use that typically includes craving and manifestations of tolerance and/or withdrawal along with adverse psychosocial consequences. Alcoholism... read more also appears to be increased after bariatric surgery (3 Risks references Bariatric surgery is the surgical alteration of the stomach, intestine, or both to cause weight loss. In the US, about 250,000 bariatric operations are done in each year. Development of safer... read more ).

Eating habits may be disordered. Adjusting to new eating habits can be difficult.

In hospitals accredited by the American Society of Bariatric Surgery as centers of excellence (COE), overall 30-day mortality is 0.2 to 0.3%. However, some data indicate that lower rates of serious complications are predicted more accurately by the number of procedures done in the hospital and by the surgeon than by COE status.

Mortality is higher with Roux-en-Y gastric bypass (RYGB) than laparoscopic adjustable gastric banding and higher with open procedures (2.1%) than laparoscopic procedures (0.2%). Factors that predict higher risk of mortality include a history of deep venous thrombosis Deep Venous Thrombosis (DVT) Deep venous thrombosis (DVT) is clotting of blood in a deep vein of an extremity (usually calf or thigh) or the pelvis. DVT is the primary cause of pulmonary embolism. DVT results from conditions... read more or pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism (PE) is the occlusion of pulmonary arteries by thrombi that originate elsewhere, typically in the large veins of the legs or pelvis. Risk factors for pulmonary embolism are... read more , obstructive sleep apnea Obstructive Sleep Apnea (OSA) Obstructive sleep apnea (OSA) consists of multiple episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of... read more , and poor functional status. Other factors such as severe obesity Obesity Obesity is excess body weight, defined as a body mass index (BMI) of ≥ 30 kg/m². Complications include cardiovascular disorders (particularly in people with excess abdominal fat)... read more (BMI > 50), older age, and male sex have also been associated with higher risk, but the evidence is inconsistent.

Average excess weight loss depends on the procedure.

For laparoscopic adjustable gastric banding, weight loss is

Percentage of weight loss is related to the frequency of follow-ups and number of band adjustments. Patients with a lower BMI tend to lose more excess weight than those with a higher BMI.

For sleeve gastrectomy, weight loss is

Longer-term data are not available.

For Roux-en-Y gastric bypass, weight loss is

Weight loss after RYGB is maintained for up to 10 years.

Comorbid conditions that tend to abate or resolve after bariatric surgery include cardiovascular risk factors (eg, dyslipidemia Dyslipidemia Dyslipidemia is elevation of plasma cholesterol, triglycerides (TGs), or both, or a low high-density lipoprotein cholesterol level that contributes to the development of atherosclerosis... read more , hypertension, diabetes), cardiovascular disorders, diabetes, obstructive sleep apnea Obstructive Sleep Apnea (OSA) Obstructive sleep apnea (OSA) consists of multiple episodes of partial or complete closure of the upper airway that occur during sleep and lead to breathing cessation (defined as a period of... read more , osteoarthritis, and depression Depressive Disorders Depressive disorders are characterized by sadness severe enough or persistent enough to interfere with function and often by decreased interest or pleasure in activities. Exact cause is unknown... read more . Diabetes is particularly likely to remit (eg, with RYGB, up to 62% of patients at 6 years). All-cause mortality decreases by 25%, primarily because cardiovascular and cancer mortality is reduced.

Regular, long-term follow-up after bariatric surgery helps ensure adequate weight loss and prevent complications. After Roux-en-Y gastric bypass or sleeve gastrectomy, patients should be monitored every 4 to 12 weeks during the period of rapid weight loss (usually about the first 6 months after surgery), then every 6 to 12 months thereafter. With laparoscopic adjustable gastric banding, results appear to be optimal when patients are monitored and the band is adjusted at least 6 times during the first year after surgery.

Weight and blood pressure are checked, and eating habits are reviewed. Blood tests (usually complete blood count, electrolytes, glucose, blood urea nitrogen, creatinine, albumin, and protein and liver tests) are done at regular intervals. Glycosylated Hb (HbA1c) and fasting lipid levels should be monitored if they were abnormal before surgery. Depending on the type of procedure, vitamin and mineral levels, including calcium, vitamin D, vitamin B12, folate, iron, and thiamin (vitamin B1), may need to be monitored. Because secondary hyperparathyroidism is a risk, parathyroid hormone levels should also be monitored. Bone density should be measured after sleeve gastrectomy or Roux-en-Y gastric bypass.

Clinicians should check for any changes in response to antihypertensives, insulin, oral hypoglycemics, or lipid-lowering drugs during the period of rapid weight loss after surgery.

Patients should be regularly evaluated for gout Gout Gout is a disorder caused by hyperuricemia (serum urate > 6.8 mg/dL [> 0.4 mmol/L]) that results in the precipitation of monosodium urate crystals in and around joints, most often causing recurrent... read more , cholelithiasis Cholelithiasis Cholelithiasis is the presence of one or more calculi (gallstones) in the gallbladder. In developed countries, about 10% of adults and 20% of people > 65 years have gallstones. Gallstones... read more , and nephrolithiasis Urinary Calculi Urinary calculi are solid particles in the urinary system. They may cause pain, nausea, vomiting, hematuria, and, possibly, chills and fever due to secondary infection. Diagnosis is based on... read more , all of which can develop after bariatric surgery. Prophylactic ursodiol reduces risk of cholelithiasis and should be offered after bariatric surgery. Patients should also be regularly screened for depression Diagnosis Depressive disorders are characterized by sadness severe enough or persistent enough to interfere with function and often by decreased interest or pleasure in activities. Exact cause is unknown... read more and alcohol use Screening Alcohol use disorder involves a pattern of alcohol use that typically includes craving and manifestations of tolerance and/or withdrawal along with adverse psychosocial consequences. Alcoholism... read more , particularly if alcohol use was heavy preoperatively.

To minimize risk of hypoglycemia Hypoglycemia Hypoglycemia, or low plasma glucose level can result in sympathetic nervous system stimulation, and central nervous system dysfunction. In patients with diabetes who take insulin or antihyperglycemic... read more (due to increased insulin sensitivity after bariatric surgery) in patients with diabetes, clinicians should adjust the dose of insulin and decrease the dose of oral hypoglycemics (particularly sulfonylureas) or stop them after Roux-en-Y gastric bypass or sleeve gastrectomy.