Bariatric (weight-loss) surgery alters the stomach, intestine, or both to produce weight loss.
In the United States, about 160,000 people have bariatric surgery each year. This number accounts for almost two thirds of the total number of bariatric procedures done worldwide. These procedures result in substantial weight loss. People may lose half or even more of their excess weight and as much as 80 to 160 pounds. Weight loss is rapid at first and then slows gradually over a period of about 1 to 2 years. Weight loss is often maintained for years. The loss greatly reduces the severity and risk of weight-related medical problems (such as sleep apnea and diabetes). It improves mood, self-esteem, body image, activity level, and the ability to work and interact with other people.
When obesity is severe—for example, if body mass index (BMI) is 40 or higher—surgery is the treatment of choice. Surgery is also appropriate when people with a BMI 35 or higher have serious weight-related health problems, such as diabetes, high blood pressure, sleep apnea, or heart failure. Bariatric surgery should also be considered for people with a BMI of 30 to 34.9 with type 2 diabetes who have poor glycemic control even after appropriate lifestyle changes and drug treatment.
To qualify for surgery, people also need to do the following:
- Understand the risks and effects of bariatric surgery
- Be motivated to follow the changes in diet and lifestyle required after surgery
- Have tried other methods of losing weight
- Be physically and mentally able to undergo surgery
Usually, age alone is not a factor when bariatric surgery is being considered. In people under 18, bariatric surgery has had good short-term results. However, experience with this surgery in this age group is limited. Many people over 65 have had a bariatric procedure, but results have been mixed, and the risk of complications may be higher. However, in this age group, other factors, such as whether a person has other disorders or can function well, may be more important than age.
Surgery is not appropriate if people
- Have a psychiatric disorder that is not under control (such as major depression)
- Abuse drugs or alcohol
- Have cancer that is not in remission or another life-threatening disorder
Bariatric surgery is done using one of two methods:
- Open abdominal surgery
Laparoscopy is usually used. For this procedure, a flexible viewing tube (laparoscope) is inserted into a small incision (about 1 inch long) just below the navel. Four to six other surgical instruments are then inserted into the abdomen through similar small incisions. Whether laparoscopy can be used depends on the type of procedure and the person’s size.
If laparoscopy cannot be used, surgery involves a larger abdominal incision (called open abdominal surgery, or laparotomy). Compared with open abdominal surgery, laparoscopy is much less invasive and recovery is much more rapid.
Bariatric surgery may involve
- Reducing the size of the stomach permanently, sometimes bypassing part of the small intestine (for example, the Roux-en-Y gastric bypass)
- Using a band to constrict the stomach (for example, adjustable gastric banding)
Both of these procedures limit the amount of food people can eat.
The most common procedures done in the United States include the Roux-en-Y gastric bypass, sleeve gastrectomy, and adjustable gastric banding.
Roux-en-Y gastric bypass
The Roux-en-Y gastric bypass can often be done using a laparoscope.
For Roux-en-Y gastric bypass, a small part of the stomach is detached from the rest, creating a small stomach pouch. As a result, the amount of food that can be eaten at one time is drastically reduced. The stomach pouch is connected to a lower part of the small intestine (called the jejunum). Thus, a large part of the small intestine is bypassed. This arrangement resembles a Y—hence the name. The opening between the pouch and the intestine is made narrow. As a result, food moves slowly out of the pouch into the intestine, and people may feel full for a longer time. Because food bypasses the lower part of the stomach and the upper part of the small intestine (duodenum), where much of the absorption occurs, the amount of food and calories absorbed is reduced. However, digestive juices (bile acids and pancreatic enzymes) still mix with food, although in a lower part of the small intestine. Thus, food is digested, and nutrients, including vitamins and minerals, are still absorbed, reducing the risk of nutritional deficiencies.
Gastric bypass (and sleeve gastrectomy) results in certain hormonal changes. These changes may result in feeling full sooner and may contribute to weight loss. These changes also improve how the body uses glucose (a sugar), possibly helping reduce the severity of diabetes or causing it to resolve.
Most people stay in the hospital overnight or longer.
For many people who have had a gastric bypass, eating foods high in fat and refined sugar can cause dumping syndrome. Symptoms include indigestion, nausea, diarrhea, abdominal pain, sweating, light-headedness, and weakness. Dumping syndrome occurs when undigested food from the stomach moves into the small intestine too quickly.
Bypassing Part of the Digestive Tract
For the Roux-en-Y gastric bypass, part of the stomach is detached from the rest, creating a small pouch. The pouch is connected to a lower part of the small intestine—an arrangement that resembles a Y. As a result, parts of the stomach and small intestine are bypassed. However, digestive juices (bile acids and pancreatic enzymes) can still mix with food, enabling the body to absorb vitamins and minerals and reducing the risk of nutritional deficiencies.
Sleeve gastrectomy is used to treat severe obesity in the United States. It causes substantial and sustained weight loss.
Part of the stomach is removed, making the stomach into a narrow tube (sleeve). The small intestine is not altered.
Sleeve gastrectomy results in certain hormonal changes, which may result in feeling full sooner and which may contribute to weight loss. These changes also improve how the body uses glucose, possibly helping reduce the severity of diabetes.
Adjustable gastric banding
Adjustable gastric banding is being used less often in the United States. It can be done using a laparoscope.
A band is placed at the upper end of the stomach to divide the stomach into a small upper part and a large lower part. Food passes through the band on its way to the intestine, but the band slows the passage of food. Connected to the band is a piece of tubing with a device that allows access to the band at the other end of the tube (through a port). The port is placed just under the skin so that doctors can adjust the tightness of the band after surgery. Doctors can inject fluid through the port into the band to expand it and make the passageway between the upper and lower stomach smaller. Or they can remove fluid from the band to make the passageway larger. When the passageway is smaller, the upper part of the stomach fills more quickly, sending a message to the brain that the stomach is full. As a result, people eat smaller meals and lose substantial amounts of weight over time.
Banding the Stomach
For adjustable gastric banding, an adjustable band is placed around the upper part of the stomach. It enables doctors to adjust the size of the passageway for food through the stomach as needed.
After a small incision is made in the abdomen, a viewing tube (laparoscope) is inserted. While looking through the laparoscope, the surgeon places the band around the upper part of the stomach. On the inside of the band is an inflatable ring, which is connected to tubing with a small port at the other end. The port is placed just under the skin. A special needle can be inserted into the port through the skin. The needle is used to insert a salt water (saline) solution into the band or to remove it. Thus, the passageway can be made smaller or larger. When the passageway is smaller, the upper part of the stomach fills faster, causing people to feel full more quickly and thus eat less.
Biliopancreatic diversion with a duodenal switch
Biliopancreatic diversion with a duodenal switch accounts for fewer than 5% of bariatric procedures done in the United States. This procedure can sometimes be done using a laparoscope.
Part of the stomach is removed. In contrast to the Roux-en-Y gastric bypass, the part of the stomach that is left connects normally to the esophagus and the small intestine. Also, the valve between the stomach and small intestine is left intact and can function normally. Thus, the stomach empties normally. However, the small intestine is divided. The part that connects to the stomach (duodenum) is cut and attached to the lower part (ileum), bypassing much of the middle part of the small intestine (jejunum). As a result, digestive juices (bile acids and pancreatic enzymes) cannot mix with food as well, and absorption is reduced. Nutritional deficiencies often result.
Before surgery, people are evaluated to determine whether surgery is likely to help them. A physical examination is done, and tests may be done. Tests may include the following:
- Tests that are routinely done before surgery to check how well vital organs are functioning
- Blood tests, including liver tests (to determine how well the liver is functioning and whether it is damaged) and measurement of blood sugar levels and cholesterol and other fat (lipid) levels (after fasting)
- Blood tests to measure vitamin D, vitamin B12, folate, and iron levels
- Electrocardiography to check for coronary artery disease
- Evaluation of the digestive tract (with x-rays or endoscopy)
- Sometimes ultrasonography of the abdomen, including the gallbladder
- Sometimes echocardiography (ultrasonography of the heart)
- Sometimes pulmonary function tests to evaluate how well the lungs are functioning—for example, if people have asthma or chronic obstructive pulmonary disease (COPD)
- Sometimes thyroid function tests
- Sometimes sleep evaluation (including polysomnography) and testing for sleep apnea
When certain disorders are detected, measures are taken to control them and thus reduce the risks of surgery. For example, high blood pressure is treated. People who smoke are advised to stop at least 8 weeks before surgery and preferably permanently. Smoking increases the risk of respiratory problems and the risk of ulcers and bleeding in the digestive tract after surgery.
Psychiatric and nutritional evaluations are also done. People should tell their doctor about any drugs or medicinal herbs they are taking. Some drugs, including anticoagulants (such as warfarin) and aspirin, may be stopped before surgery.
After Bariatric Surgery
After surgery, pain relievers are prescribed.
After bariatric surgery, some symptoms are common and do not indicate a problem. However, the following symptoms require a call or visit to the doctor:
- Signs of infection at the incision site, such as redness, severe pain, swelling, a bad odor, or oozing
- Separation of stitched edges of the incision
- Continued or increasing abdominal pain
- Persistent fever or chills
- Persistent bleeding
- Abnormal beating of the heart
- Dark, tarry, foul-smelling stools
- Shortness of breath
- Sudden paleness
- Chest pain
How quickly people can return to a normal diet varies. For about the first 2 weeks, the diet is mostly liquids. People are asked to drink small amounts frequently throughout the day. They should drink as much fluid as prescribed. Most of the fluid should be a liquid protein supplement. For the next 2 weeks, people should consume a soft diet consisting mostly of mashed or pureed high-protein foods and protein supplements. After 4 weeks, they can start eating solid foods.
The following can help people avoid digestive problems and discomfort:
- Taking small bites of food
- Chewing food thoroughly
- Avoiding high-fat and high-sugar foods, such as fast food, cakes, and cookies
- Eating only small amounts at each meal
- Avoiding drinking liquids when eating solid foods
Adjusting to new eating patterns can be difficult. People may benefit from counseling and/or support groups.
Usually, people can resume taking their routine drugs after surgery. But tablets may have to be crushed, and if people have been taking long-acting or sustained-release formulations of drugs, doctors must switch them to immediate-release formulations.
People should start walking or doing leg exercises the day after surgery. To avoid blood clots, they should not stay in bed for long periods of time. They can return to their usual activities after about 1 week and to their usual exercises (such as aerobics and strength training) after a few weeks. They should consult their doctor before doing any heavy lifting and manual labor, which should usually be avoided for 6 weeks.
People may experience pain, and some have nausea and vomiting. Constipation is common. Drinking more fluids and not staying in bed too long at a time can help relieve constipation.
Serious complications, such as problems with the incision, infections, blood clots that travel to the lungs (pulmonary embolism), and lung problems, can occur after any operation (see Surgery: After Surgery).
In addition, the following complications can occur after bariatric surgery:
- Blockage of the intestine: In about 2 to 4% of people, the intestine becomes blocked because it becomes twisted or scar tissue forms. A blockage can develop weeks to months to years after surgery. Symptoms include severe abdominal pain, nausea, vomiting, difficulty passing gas, and constipation.
- Leakage: In about 1 to 3% of people, the new connection between the stomach and intestine leaks. Leakage usually occurs within 2 weeks of surgery. As a result, the stomach’s contents can leak into the abdominal cavity and cause a serious infection (peritonitis). Symptoms include a fast heart rate, abdominal pain, fever, shortness of breath, and a general sick feeling.
- Bleeding: Bleeding may occur at the connection between the stomach and intestine, elsewhere in the digestive tract, or in the abdominal cavity. People may vomit blood or have bloody diarrhea or dark, tarry stools.
- Gallstones: Many people who successfully follow a diet aimed at quick weight loss develop gallstones. To reduce this risk after bariatric surgery, people are given supplemental bile salts, which make gallstones less likely to form but do not always prevent them. Up to 15% of people who have bariatric surgery need to have their gallbladder removed later.
- Kidney stones: Roux-en-Y gastric bypass slightly increases the risk of kidney stones because oxalate accumulates in urine. A high level of oxalate in the urine contributes to calcium stone formation. To prevent stones from forming, people are advised to avoid eating foods that contain oxalate after this surgery. Foods that are high in oxalate include spinach, rhubarb, almonds, baked potatoes with the skin, corn grits, and soy flour.
- Gout: Obesity increases the risk of developing gout. In people with gout, gout attacks may occur more frequently after bariatric surgery.
- Nutritional deficiencies: If people do not make a concentrated effort to eat enough protein, a protein deficiency may develop. Vitamins and minerals (such as vitamins B12 and D, calcium, and iron) may not be absorbed as well after the surgery. Thiamin deficiency can occur if vomiting continues for a long time. People need to take vitamin supplements and sometimes mineral or other supplements (depending on the type of surgery) for the rest of their life.
- Reproductive health: Fertility in women of reproductive age may improve after surgery. These women should consider contraceptive choices before and after bariatric procedures, avoid pregnancy prior to surgery, and avoid pregnancy for 12 to 18 months after surgery.
- Death: In specially accredited hospitals, about 0.2 to 0.3% of people die during the first month after surgery. The risk of death (and serious complications) may be higher at other hospitals. Causes of death include a blood clot that travels to the lungs, a severe infection due to leakage of one of the connections in the stomach or intestine, a heart attack, pneumonia, and blockage of the small intestine. Risk is higher for people who have had blood clots or obstructive sleep apnea and for people who were not functioning well before surgery. Being very obese, male, or older may increase the risk of death. The risk of death is higher with Roux-en-Y gastric bypass than with adjustable gastric bands and higher with open abdominal surgery (2.1%) than with laparoscopy (0.2%).
Average weight loss after surgery depends on the procedure. Weight loss is usually described as a percentage of excess weight lost. Excess weight is defined as the difference between a person's actual and ideal weight.
For adjustable gastric banding done using a laparoscope, weight loss is
- 45 to 72% after 3 to 6 years
- 14 to 60% after 7 to 10 years
- Up to 47% at 15 years
How much weight is lost depends on how often people see their doctor after surgery and how often the band is readjusted. People with a lower BMI before surgery tend to lose more weight. Some people have to have another operation.
For sleeve gastrectomy, weight loss is
- 33 to 58% after 2 years
- 58 to 72% after 3 to 6 years
For Roux-en-Y gastric bypass, weight loss is
- 50 to 65% after 2 years
Although most people gain some weight back, most weight loss can be maintained for up to 10 years, particularly after a Roux-en-Y gastric bypass.
Visits to the doctor are usually scheduled every 4 to 12 weeks during the first several months after Roux-en-Y gastric bypass or sleeve gastrectomy—the time when weight loss is most rapid. Then visits are scheduled every 6 to 12 months. After adjustable gastric bypass done using a laparoscope, at least six visits are scheduled during the first year. At these visits, weight and blood pressure are measured, and eating habits are discussed. People should report any problems they are having. Blood tests are done at regular intervals. Bone density, usually with dual-energy x-ray absorptiometry (DXA), is measured after Roux-en-Y gastric bypass or sleeve gastrectomy to check for bone loss due to vitamin D deficiency.
Doctors also check whether people are responding differently to certain drugs after surgery. These drugs include those used to treat high blood pressure (antihypertensives), diabetes (hypoglycemic drugs and insulin), or high cholesterol levels (lipid-lowering drugs).
Many disorders that were present before surgery tend to resolve or become less severe after bariatric surgery. These disorders include some heart problems, diabetes, obstructive sleep apnea, arthritis, and depression. Diabetes resolves in up to 62% of people 6 years after Roux-en-Y gastric bypass.
Risk of death decreases by 25%, mainly because risk of death due to heart disorders or cancer is reduced.
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