Bariatric surgery, also known as weight loss surgery, refers to the various surgical procedures performed to treat obesity by modification of the gastrointestinal tract to reduce nutrient intake and/or absorption. The term does not include procedures for surgical removal of body fat such as liposuction or abdominoplasty.

For individuals who have been unable to achieve significant weight loss through diet modifications and exercise programs alone, bariatric surgery may help to attain a more healthy body weight. There are a number of surgical options available to treat obesity, each with its advantages and pitfalls. In general, bariatric surgery is successful in producing (often substantial) weight loss, though one must consider operative risk (including mortality) and side effects before making the decision to pursue this treatment option. Usually, these procedures can be carried out safely.^[1]

[edit] Indications

A clinical practice guideline by the American College of Physicians concluded^[2][3]:

• "Surgery should be considered as a treatment option for patients with a BMI of 40 kg/m ² or greater who instituted but failed an adequate exercise and diet program (with or without adjunctive drug therapy) and who present with obesity-related comorbid conditions, such as hypertension, impaired glucose tolerance, diabetes mellitus, hyperlipidemia, and obstructive sleep apnea. A doctor–patient discussion of surgical options should include the long-term side effects, such as possible need for reoperation, gall bladder disease, and malabsorption."
• "Patients should be referred to high-volume centers with surgeons experienced in bariatric surgery."

[edit] Classification of surgical procedures

Procedures can be grouped in three main categories:^[4]

[edit] Predominantly malabsorptive procedures

Predominantly malabsorptive procedures, although they also reduce stomach size, these operations are based mainly on creating malabsorption.

Diagram of a biliopancreatic diversion.

[edit] Biliopancreatic diversion

This complex operation is also known as biliopancreatic diversion (BPD), or Scopinaro procedure. This surgery is rare now because of problems with malnourishment. It has been replaced with the Duodenal Switch, also known as the BPD/DS. Part of the stomach is resected, creating a smaller stomach (however after a few months the patient can eat a completely free diet as there is no restrictive component). The distal part of the small intestine is then connected to the pouch, bypassing the duodenum and jejunum. This results, in around 2% of patients, in severe malabsorption and nutritional deficiency that requires restoration on the normal absorption.

The malabsorptive element of BPD is so potent that those who undergo the procedure must take vitamin and mineral supplements above and beyond that of the normal population. Those who do not, run the risk of deficiency diseases such as anemia and osteoporosis.

Because gallstones are a common complication of rapid weight loss following any type of weight loss surgery, some surgeons may remove the gall bladder as a preventative measure during BPD. Others prefer to prescribe medication to reduce the risk of post-operative gallstones.

Far fewer surgeons perform BPD compared to other weight loss surgeries, in part because of the need for long-term nutritional follow-up and monitoring of BPD patients.

[edit] Jejuno-ileal bypass

Main article: Jejuno-ileal bypass

This procedure is no longer performed.

[edit] Predominantly restrictive procedures

Predominantly restrictive procedures primarily reduces stomach size.

Diagram of a vertical banded gastroplasty.

[edit] Vertical Banded Gastroplasty

Main article: Vertical banded gastroplasty surgery

In the vertical banded gastroplasty, also called the Mason procedure or stomach stapling, a part of the stomach is permanently stapled to create a smaller pre-stomach pouch, which serves as the new stomach.

Diagram of an adjustable gastric banding.

[edit] Adjustable gastric band

Main article: Adjustable Gastric Banding

The same effect can be created using a silicone band, which can be adjusted by addition or removal of saline through a port placed just under the skin. This operation can be performed laparoscopically, and is commonly referred to as a "lap band." The first gastric band was patented in 1985 by Obtech Medical of Sweden (now owned by J&J/Ethicon) and is known as the Swedish Adjustable Gastric Band (SAGB). An American company, INAMED Health, later designed the BioEnterics LAP-BAND Adjustable Gastric Banding System. The LAP-BAND System was introduced in Europe in 1993. Neither of these bands was initially designed for use with keyhole surgery. The LAP-BAND System received Food and Drug Administration (FDA) approval for use in the United States in June 2001. In 2000, the first lower pressure, wider, one-piece adjustable gastric band called the MIDband was introduced in Lyon France by Medical Innovation Development.^[5] In 2002, the first lower pressure, wider, one-piece adjustable gastric band called the Bioring was introduced in France by Cousin-Biotech.^[6] Unlike many of the early bands this was designed specifically for laparoscopic insertion. It has swiftly become one of the leading bands placed in France. There are now many band manufacturers (approx 7-8 in total).

[edit] Sleeve gastrectomy

Main article: Sleeve gastrectomy

[edit] Mixed procedures

Mixed procedures apply both techniques simultaneously.

Roux-en-Y gastric bypass.

[edit] Gastric Bypass Surgery

Main article: Gastric bypass surgery

The most common form of gastric bypass surgery is Roux-en-Y gastric bypass surgery. Here, a small stomach pouch is created with a stapler device, and connected to the distal small intestine. The upper part of the small intestine is then reattached in a Y-shaped configuration.

The gastric bypass is the most commonly performed operation for weight loss in the United States. In the U.S, approximately 140,000 gastric bypass procedures were performed in 2005, an amount dwarfing the number of Lap-Band, duodenal switch and vertical banded gastroplasty procedures done. Furthermore, since the gastric bypass has been performed for almost 50 years, surgeons have become very comfortable with, and understanding of, the risks and benefits of the procedure. By sheer volume of cases combined with the volume of scientific research, the gastric bypass has become the "gold standard" operation for weight loss in the U.S. An emerging factor in the success of gastric bypass surgery is following an established gastric bypass diet after surgery

Diagram of a sleeve gastrectomy with duodenal switch.

[edit] Sleeve gastrectomy with duodenal switch

A variation of the biliopancreatic diversion includes a Duodenal switch. The part of the stomach along its greater curve is resected. The stomach is "tubulized" with a residual volume of about 150 ml. This volume reduction provides the food intake restriction component of this operation. This type of gastric resection is anatomically and functionally irreversible. The stomach is then disconnected from the duodenum and connected to the distal part of the small intestine. The duodenum and the upper part of the small intestine are reattached to the rest at about 75-100 cm from the colon.

[edit] Implantable Gastric Stimulation

This procedure where a device similar to a heart pacemaker is implanted by a surgeon, with the electrical leads stimulating the external surface of the stomach, is being tested in the USA. The electrical stimulation is thought to modify the activity of the Enteric nervous system in the stomach, which is then interpreted by the brain as a sense of satiety, or fullness. Early evidence suggests that it is less effective than other forms of Bariatric Surgery.

[edit] Effectiveness of surgery

[edit] Weight loss

In general, the malabsorptive procedures lead to more weight loss than the restrictive procedures. A meta-analysis from UCLA reports the following weight loss at 36 months:^[3]

• Biliopancreatic diversion - 53 kg
• Roux-en-Y gastric bypass (RYGB) - 41 kg
  • Open - 42 kg
  • Laparoscopic - 38 kg
• Adjustable gastric banding - 35 kg
• Vertical banded gastroplasty - 32 kg

[edit] Reduced mortality and morbidity

Several recent studies report decrease in mortality and severity of medical conditions after bariatric surgery.^[7][8][9] In the Swedish prospective matched controlled trial, patients with a body mass index (BMI) of 34 or more for men and 38 or more for women underwent various types of bariatric surgery and were followed for an average of 11 years. Surgery patients had 5.0% mortality while control patients had 6.3% mortality. This means 75 patients must be treated to avoid one death after 11 years (number needed to treat is 77).^[7]

In a Utah retrospective cohort study that followed patients for an average of 7 years after various types of gastric bypass, surgery patients had 0.4% mortality while control patients had 0.6% mortality.^[8] Death rates were lower in the gastric bypass patients for all diseases combined, as well as for diabetes, heart disease and cancer. Deaths from accident and suicide were 58% higher in the surgery group.

A randomized, controlled trial in Australia compared laparoscopic adjustable gastric banding ("lap banding") with non-surgical therapy in 80 moderately obese adults (BMI 30-35). At 2 years, the surgically-treated group lost more weight (21.6% of initial weight vs. 5.5%) and had statistically significant improvement in blood pressure, measures of diabetic control, and HDL cholesterol.^[9] Post surgical complications included 1 patient with an infected surgical site, 4 with lap band malpositioning requiring laparoscopic revision, and 1 patient with cholecystitis. In the non-surgical group, 12 patients declined or did not tolerate orlistat or diet restrictions, and 4 patients developed acute cholecystitis.

Bariatric surgery in older patients has also been a topic of debate, centered on concerns for safety in this population. One study of elderly patients undergoing laparoscopic bariatric surgery at Mount Sinai Medical Center, however, reported 0% conversion to open surgery, 0% 30-day mortality, 7.3% complication rate, and average hospital stay of 2.8 days.^[10]

[edit] Adverse effects

Complications from weight loss surgery are frequent. A study of insurance claims of 2522 who had undergone bariatric surgery showed 21.9% complications during the initial hospital stay and a total of 40% risk of complications in the subsequent six months. This was more common in those over 40 and led to increased health care expenditure. Common problems were gastric dumping syndrome in about 20% (bloatedness and diarrhoea after eating, necessitating small meals or medication), leaks at the surgical site (12%), incisional hernia (7%), infections (6%) and pneumonia (4%). Mortality was 0.2%.^[11] As the rate of complications appears to be reduced when the procedure is performed by an experienced surgeon, guidelines recommend that surgery is performed in dedicated or experienced units.^[2]

[edit] References