Contraindications to bariatric surgery include patients with untreated major depression or psychosis, binge eating disorders, current drug and alcohol abuse, severe cardiac disease with prohibitive anesthetic risks, severe coagulopathy, or inability to comply with nutritional requirements including life-long vitamin replacement. Bariatric surgery in advanced (above 65) or very young age (under 18) is controversial.

Bariatric surgery needs to be performed in conjunction with a comprehensive follow-up plan consisting of nutritional, behavioral, and medical programs. The American Society of Bariatric Surgeons (ASBS) has announced guidelines for establishing Centers of Excellence (COE) for bariatric facilities [28]. Patient safety is clearly the driving force behind such a process and is emphasized by several items:

An integrated program that is capable of providing the pre- and post-operative care of a bariatric patient by necessary multi-specialty consultants
Ability to follow 75 percent of post-surgical patients long-term out to five years
Monitored credentialing of bariatric surgeons and hospitals based upon demonstration of adequate training, equipment, and periodic outcomes assessment.
TYPES OF BARIATRIC PROCEDURES — Bariatric surgical procedures can be divided fundamentally into two varieties, malabsorptive and restrictive, based upon the mechanism by which they induce weight loss (show table 3).

Restrictive procedures limit caloric intake by downsizing the stomach's reservoir capacity. Vertical banded gastroplasty (VBG) and laparoscopic adjustable gastric banding (LAGB) are purely restrictive procedures and share similar anatomical configurations. Both limit solid food intake by restriction of stomach size as the only mechanism of action, leaving the absorptive function of the small intestine intact. Although these procedures are simpler in comparison to malabsorptive procedures, they tend to produce more gradual weight loss.
The primary mechanism of malabsorptive procedures is to decrease the effectiveness of nutrient absorption by shortening the length of the functional small intestine. Jejunoileal bypass (JIB), the biliopancreatic diversion (BPD), and duodenal switch operation (DS) are examples of malabsorptive procedures. Profound weight loss can be achieved by the malabsorptive operations depending upon the effective length of the functional small bowel segment. However, the benefit of superior weight loss is often offset by the significant metabolic complications such as protein calorie malnutrition and various micronutrient deficiencies.
Some procedures have both a restrictive and malabsorptive component. The Roux-en-Y gastric bypass (RYGB), for example, is primarily a restrictive operation in which a small gastric pouch limits oral intake. However, the small bowel reconfiguration provides additional mechanisms favoring weight loss including dumping physiology and mild malabsorption.

Minimally invasive techniques were first applied in bariatric surgery in the 1990s. The first laparoscopic RYGB series was reported in 1994 in the United States [29]. Although technically intensive with a steep learning curve, laparoscopic RYGB can be performed safely by experienced surgeons. The laparoscopic approach offers the advantages of decreased post-operative pain, shorter hospital stay, and decreased rates of wound infection and hernia formation.

An increasing number of laparoscopic RYGB and LAGB are b**** performed in the United States, indicating a trend towards minimally invasive approaches to bariatric surgery. Investigation of the cost-effectiveness and safety of these laparoscopic procedures is ongoing.

RESTRICTIVE

Vertical banded gastroplasty — Vertical banded gastroplasty (VBG) is a purely restrictive procedure in which the upper part of the stomach is partitioned by a vertical staple line with a tight outlet wrapped by a prosthetic mesh or band (show figure 1). It is often referred to as a stomach stapling operation.

The small upper stomach pouch gets filled quickly by solid food and prevents consumption of a large meal. Weight loss occurs because of decreased caloric intake of solid food. Patients who have undergone VBG can be expected to have excess weight loss (EWL) of up to 66 percent at two years, which subsequently decreases to 55 percent at nine years [30]. The effectiveness of such a restrictive mechanism depends upon the durability of pouch and stoma (outlet) size.

Ingestion of high-calorie liquid meals along with gradually increased pouch capacity due to overeating have been some of the major causes of its failure.
Sweets eaters who rely on soft meals (ie, ice cream, milk shakes) do not benefit significantly from this procedure [31].

VBG has been replaced largely by other procedures due to lack of sustained/desired weight loss as well as the high incidence of complications requiring revision (20 to 56 percent) [31-36]. The majority of revisions are required for staple line disruption, stomal stenosis, band erosion, band disruption, pouch dilatation, vomiting, and gastroesophageal reflux disease. (See "Complications of bariatric surgery").

Laparoscopic adjustable gastric banding — Laparoscopic gastric banding (LAGB) is a purely restrictive procedure that compartmentalizes the upper stomach by placing a tight, adjustable prosthetic band around the entrance to the stomach (show figure 2). Although it has been performed extensively in Europe and Australia for almost a decade, it was not until June 2001 when the LapBand ™ (Inamed) was approved for use in the United States. Over 100,000 bands have been placed worldwide.

The band consists of a soft, locking silicone ring connected to an infusion port placed in the subcutaneous tissue. The port may be accessed with relative ease by a syringe and needle. Injection of saline into the port leads to reduction in the band diameter, resulting in an increased degree of restriction. The currently available band is adjustable and is placed laparoscopically [37,38].

Indications for the use of LAGB are similar to the indications for gastric bypass and patients must meet full NIH criteria [27]. LAGB is generally contraindicated in patients with Crohn's disease, large hiatal hernias, portal hypertension, connective tissue disorders, prior gastric ulcers, or chronic steroid use (relative contraindication).

LAGB is gaining significant attention among bariatric surgeons and patients primarily because of its simplicity and lower complication rates when compared to more involved procedures such as RYGB [39]. Because of its many advantages, it has largely replaced the conventional VBG as the main restrictive procedure for treatment of morbid obesity:

It does not require division of the stomach or intestinal resection. As a result, it has the lowest mortality rate (0 to 0.5 percent) among all bariatric procedures [40,41].
The band eliminates the need for staple lines used in VBG that may break down and cause weight regain.
Avoidance of a fixed prosthetic mesh at the stoma reduces the incidence of stomal stenosis seen in VBG.
The adjustability of the outlet by the new band design offers a theoretical advantage of addressing various nutritional issues after surgery. As an example, a patient who becomes pregnant following this procedure may have her stoma widened to allow for greater caloric and fluid intake, if necessary. In addition, the band is reversible, allowing for easy restoration of the original anatomy by the removal of the band.
The effectiveness of the LAGB for achieving weight loss has been variable in different reports. European and Australian data indicate a 15 to 20 percent EWL at three months, 40 to 53 percent EWL at one year, with eventual increases in up to 45 to 58 percent EWL after year two [42]. Initial American experience in a seminal study was disappointing with two year EWL of only 36 percent [41]. However, the design and conduct of the study were criticized as the causes of the relatively poor outcome [43]. Subsequent American data were similar to the European and Australian experience, with EWL of 45 to 75 percent at two years [44-46].

As a general rule, weight loss following LAGB is more gradual compared with gastric bypass procedures, but may be comparable over the long-term [40]. Persistent weight loss requires close follow-up and frequent band adjustments. In addition to weight loss, LAGB is associated with improvements in various comorbidities (diabetes, asthma, sleep apnea, hypertension) and quality of life [6,7,40,47-50].