Gastric Bypass

Process of a Gastric Bypass

Gastric bypass procedures (GBP) are any of a group of similar operations used to treat morbid obesity—the severe accumulation of excess weight as fatty tissue—and the health problems (co-morbidities) it causes. Bariatric surgery is the term encompassing all of the surgical treatments for morbid obesity, not just gastric bypasses, which make up only one class of such operations.

A gastric bypass first divides the stomach into a small upper pouch and a much larger, lower "remnant" pouch and then re-arranges the small intestine to allow both pouches to stay connected to it. Surgeons have developed several different ways to reconnect the intestine, thus leading to several different GBP names. Any GBP leads to a marked reduction in the functional volume of the stomach, accompanied by an altered physiological and psychological response to food. The resulting weight loss, typically dramatic, markedly reduces co-morbidities. The long-term mortality rate of gastric bypass patients has been shown to be reduced by up to 40%; however, slightly higher risk and complications are common and surgery-related death occurs within one month in 2% of patients.

Variations of the gastric bypass:

Laparoscopic Gastric Bypass

Gastric bypass, Roux en-Y (proximal)

This variant is the most commonly employed gastric bypass technique, and is by far the most commonly performed bariatric procedure in the United States. It is the operation which is least likely to result in nutritional difficulties. The small bowel is divided about 45 cm (18 in) below the lower stomach outlet, and is re-arranged into a Y-configuration, to enable outflow of food from the small upper stomach pouch, via a "Roux limb". In the proximal version, the Y-intersection is formed near the upper (proximal) end of the small bowel. The Roux limb is constructed with a length of 80 to 150 cm (31 to 59 in), preserving most of the small bowel for absorption of nutrients. The patient experiences very rapid onset of a sense of stomach-fullness, followed by a feeling of growing satiety, or "indifference" to food, shortly after the start of a meal.

Gastric bypass, Roux en-Y (distal)

The normal small bowel is 600 to 1,000 cm (20 to 33 ft) in length. As the Y-connection is moved farther down the gastrointestinal tract, the amount of bowel capable of fully absorbing nutrients is progressively reduced, in pursuit of greater effectiveness of the operation. The Y-connection is formed much closer to the lower (distal) end of the small bowel, usually 100 to 150 cm (39 to 59 in) from the lower end of the bowel, causing reduced absorption (mal-absorption) of food, primarily of fats and starches, but also of various minerals, and the fat-soluble vitamins. The unabsorbed fats and starches pass into the large intestine, where bacterial actions may act on them to produce irritants and malodorous gases. These increasing nutritional effects are traded for a relatively modest increase in total weight loss.

Loop Gastric bypass ("Mini-gastric bypass")

The first use of the gastric bypass, in 1967, used a loop of small bowel for re-construction, rather than a Y-construction as is prevalent today. Although simpler to create, this approach allowed bile and pancreatic enzymes from the small bowel to enter the esophagus, sometimes causing severe inflammation and ulceration of either the stomach or the lower esophagus. If a leak into the abdomen occurs, this corrosive fluid can cause severe consequences. Numerous studies show the loop reconstruction (Billroth II gastrojejunostomy) works more safely when placed low on the stomach, but can be a disaster when placed adjacent to the esophagus. Thus even today thousands of "loops" are used for general surgical procedures such as ulcer surgery, stomach cancer and injury to the stomach, but bariatric surgeons abandoned use of the construction in the 1970s, when it was recognized that its risk is not justified for weight management.

The Mini-Gastric Bypass, which uses the loop reconstruction, has been suggested as an alternative to the Roux en-Y procedure, due to the simplicity of its construction, which reduced the challenge of laparoscopic surgery.

What Advantages does it have?

Laparoscopic Roux-en-Y Gastric Bypass is a surgery for those who have a body mass index of 40 kg/m2 and higher, or those whose BMI is above 35 and who suffer from co-morbidity associated to obesity. The age range is from 14 to 65; nevertheless, there can be exceptions to this rule.

Laparoscopic Roux-en-Y Gastric Bypass has the following advantages:

• It does not require readjustments, only periodical control.
• It is the most common bariatric surgery since weight loss and is very successful (close to 80% of excess weight).

Disadvantages are:

• Possibility of surgical complications.
• Occasional vomiting.
• There might be the need for further surgical procedures.
• Irreversible alteration in the gastrointestinal anatomy.
• Need vitamins after surgery.

Possible complications are:

• Trans and post surgery bleeding
• "Anastomotic" leakage
• Internal hernia
• Intestinal obstruction
• Pulmonary embolus
• Obesity-related respiratory distress syndrome
• Death