Weight Loss Surgery

Weight loss surgery is an option for weight reduction in patients with clinically severe obesity, i.e., a BMI ≥40, or a BMI ≥ 35 with comorbid conditions. Weight loss surgery should be reserved for patients in whom other methods of treatment have failed and who have clinically severe obesity (once commonly referred to as “morbid obesity”). Weight loss surgery provides medically significant sustained weight loss for more than 5 years in most patients.

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Lifelong medical monitoring after surgery is a necessity. Perioperative complications vary with weight and the overall health of the individual. In the published literature, young patients without comorbidities with a BMI < 50 kg/m2 who have undergone surgery have mortality rates less than 1 percent, whereas massively obese patients with a BMI > 60 kg/m2 who are also diabetic, hypertensive, and in cardiopulmonary failure may have mortality rates that range from 2 to 4 percent. Operative complications, including anastomotic leak, subphrenic abscess, splenic injury, pulmonary embolism, wound infection, and stoma stenosis, occur in less than 10 percent of patients.

An integrated program that provides guidance on diet, physical activity, and psychosocial concerns before and after surgery is necessary. Most patients fare remarkably well with reversal of diabetes, control of hypertension, marked improvement in mobility, return of fertility, cure of pseudotumor cerebri, and significant improvement in quality of life.  Late complications are uncommon, but some patients may develop incisional hernias, gallstones, and, less commonly, weight loss failure and dumping syndrome.

Patients who do not follow the instructions to maintain an adequate intake of vitamins and minerals may develop deficiencies of vitamin B12 and iron with anemia. Neurologic symptoms may occur in unusual cases. Thus, surveillance should include monitoring indices of inadequate nutrition. Documentation of improvement in preoperative comorbidities is beneficial and advised.

Gastrointestinal surgery for obesity, also called bariatric surgery, alters the digestive process. The operations can be divided into three types: restrictive, malabsorptive, and combined restrictive/malabsorptive. Restrictive operations limit food intake by creating a narrow passage from the upper part of the stomach into the larger lower part, reducing the amount of food the stomach can hold and slowing the passage of food through the stomach. Malabsorptive operations do not limit food intake, but instead exclude most of the small intestine from the digestive tract so fewer calories and nutrients are absorbed. Malabsorptive operations, also called intestinal bypasses, are no longer recommended because they result in severe nutritional deficiencies. Combined operations use stomach restriction and a partial bypass of the small intestine.

There are several types of restrictive and combined operations. Each one has its own benefits and risks.

Restrictive Operations

Purely restrictive operations only limit food intake and do not interfere with the normal digestive process. To perform the operation, doctors create a small pouch at the top of the stomach where food enters from the esophagus. At first, the pouch holds about 1 ounce of food and later may stretch to 2-3 ounces. The lower outlet of the pouch is usually about ½ inch in diameter or smaller. This small outlet delays the emptying of food from the pouch into the larger part of the stomach and causes a feeling of fullness.
After the operation, patients can no longer eat large amounts of food at one time. Most patients can eat about ½ to 1 cup of food without discomfort or nausea, but the food has to be soft, moist, and well chewed. Patients who undergo restrictive procedures generally are not able to eat as much as those who have combined operations.

Purely restrictive operations for obesity include adjustable gastric banding (AGB) and vertical banded gastroplasty (VBG).

1. Adjustable gastric banding. In this procedure, a hollow band made of silicone rubber is placed around the stomach near its upper end, creating a small pouch and a narrow passage into the rest of the stomach (figure 2). The band is then inflated with a salt solution through a tube that connects the band to an access port placed under the skin. It can be tightened or loosened over time to change the size of the passage by increasing or decreasing the amount of salt solution.
2. Vertical banded gastroplasty. VBG uses both a band and staples to create a small stomach pouch, as illustrated in figure 3. Once the most common restrictive operation, VBG is not often used today.

Advantages: Restrictive operations are easier to perform and are generally safer than malabsorptive operations. AGB is usually done via laparoscopy, which uses smaller incisions, creates less tissue damage, and involves shorter operating time and hospital stays than open procedures. Restrictive operations can be reversed if necessary, and result in few nutritional deficiencies.

Disadvantages: Patients who undergo restrictive operations generally lose less weight than patients who have malabsorptive operations, and are less likely to maintain weight loss over the long term. Patients generally lose about half of their excess body weight in the first year after restrictive procedures. However, in the first 3 to 5 years after VBG patients may regain some of the weight they lost. By 10 years, as few as 20 percent of patients have kept the weight off. (Although there is less information about long-term results with AGB, there is some evidence that weight loss results are better than with VBG.) Some patients regain weight by eating high-calorie soft foods that easily pass through the opening to the stomach. Others are unable to change their eating habits and do not lose much weight to begin with. Successful results depend on the patient’s willingness to adopt a long-term plan of healthy eating and regular physical activity.

Risks: One of the most common risks of restrictive operations is vomiting, which occurs when the patient eats too much or the narrow passage into the larger part of the stomach is blocked. Another is slippage or wearing away of the band. A common risk of AGB is breaks in the tubing between the band and the access port. This can cause the salt solution to leak, requiring another operation to repair. Some patients experience infections and bleeding, but this is much less common than other risks. Between 15 and 20 percent of VBG patients may have to undergo a second operation for a problem related to the procedure. Although restrictive operations are the safest of the bariatric procedures, they still carry risk—in less than 1 percent of all cases, complications can result in death.

Combined Restrictive/Malabsorptive Operations

Combined operations are the most common bariatric procedures. They restrict both food intake and the amount of calories and nutrients the body absorbs.

1. Roux-en-Y gastric bypass (RGB). This operation, illustrated in figure 4, is the most common and successful combined procedure in the United States. First, the surgeon creates a small stomach pouch to restrict food intake. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the lower stomach, the duodenum (the first segment of the small intestine), and the first portion of the jejunum (the second segment of the small intestine). This reduces the amount of calories and nutrients the body absorbs. Rarely, a cholecystectomy (gall bladder removal) is performed to avoid the gallstones that may result from rapid weight loss. More commonly, patients take medication after the operation to dissolve gallstones.  

1. Biliopancreatic diversion (BPD). In this more complicated combined operation, the lower portion of the stomach is removed (see figure 5). The small pouch that remains is connected directly to the final segment of the small intestine, completely bypassing the duodenum and the jejunum. Although this procedure leads to weight loss, it is used less often than other types of operations because of the high risk for nutritional deficiencies. A variation of BPD includes a “duodenal switch” (see figure 6), which leaves a larger portion of the stomach intact, including the pyloric valve that regulates the release of stomach contents into the small intestine. It also keeps a small part of the duodenum in the digestive pathway. The larger stomach allows patients to eat more after the surgery than patients who have other types of procedures.

Advantages: Most patients lose weight quickly and continue to lose for 18 to 24 months after the procedure. With the Roux-en-Y gastric bypass, many patients maintain a weight loss of 60 to 70 percent of their excess weight for 10 years or more. With BPD, most studies report an average weight loss of 75 to 80 percent of excess weight. Because combined operations result in greater weight loss than restrictive operations, they may also be more effective in improving the health problems associated with severe obesity, such as hypertension, sleep apnea, type 2 diabetes, and osteoarthritis.

Disadvantages: Combined procedures are more difficult to perform than the restrictive procedures. They are also more likely to result in long-term nutritional deficiencies. This is because the operation causes food to bypass the duodenum and jejunum, where most iron and calcium are absorbed. Menstruating women may develop anemia because not enough vitamin B12 and iron are absorbed. Decreased absorption of calcium may also bring on osteoporosis and related bone diseases. Patients must take nutritional supplements that usually prevent these deficiencies. Patients who have the biliopancreatic diversion procedure must also take fat-soluble vitamins A, D, E, and K supplements, and require life-long use of special foods and medications.

RGB and BPD operations may also cause “dumping syndrome,” an unpleasant reaction that can occur after a meal high in simple carbohydrates, which contain sugars that are rapidly absorbed by the body. Stomach contents move too quickly through the small intestine, causing symptoms such as nausea, bloating, abdominal pain, weakness, sweating, faintness, and sometimes diarrhea after eating. Because the duodenal switch operation keeps the pyloric valve intact, it may reduce the likelihood of dumping syndrome.

Risks: In addition to risks associated with restrictive procedures such as infection, combined operations are more likely to lead to complications. The risk of death associated with these types of procedures is lower for the gastric bypass (less than 1 percent of patients) than for the biliopancreatic diversion with duodenal switch (2.5 to 5 percent). Combined operations carry a greater risk than restrictive operations for abdominal hernias (up to 28 percent), which require a follow-up operation to correct. The risk of hernia, however, is lower (about 3 percent) when laparoscopic techniques are used.

In laparoscopy, the surgeon makes one or more small incisions through which slender surgical instruments are passed. This technique eliminates the need for a large incision and creates less tissue damage. Patients who are super-obese (more than 350 pounds) or have had previous abdominal operations may not be good candidates for laparoscopy, however. Adjustable gastric banding is routinely performed via laparoscopy.

This technique is often used for Roux-en-Y gastric bypass, and although less common, biliopancreatic diversion can also be performed laparoscopically. The small incisions result in less blood loss, shorter hospitalization, a faster recovery, and fewer complications than open operations. However, combined laparoscopic procedures are more difficult to perform than open procedures and can create serious problems if done incorrectly.

With rates of overweight among youth on the rise, bariatric surgery is sometimes considered as a treatment option for adolescents who are severely overweight. However, there are many concerns about the long-term effects of this type of operation on adolescents’ developing bodies and minds. Experts in pediatric overweight and bariatric surgery recommend that surgical treatment only be considered when adolescents have tried for at least 6 months to lose weight and have not been successful. Candidates should be severely overweight (BMI of 40 or more), have reached their adult height (usually 13 or older for girls, 15 or older for boys), and have serious weight-related health problems such as type 2 diabetes or heart disease. In addition, potential patients and their parents should be evaluated to see how emotionally prepared they are for the operation and the lifestyle changes they will need to make. Patients should also be referred to a team of experts in adolescent medicine and bariatric surgery who are qualified to meet their unique needs.