(Malabsorptive Procedure, Roux-en-Y Gastric Bypass, Biliopancreatic Diversion)
What is gastric bypass surgery?
Gastric bypass surgery, a type of bariatric surgery (weight loss surgery), is a surgical procedure that alters the process of digestion. Bariatric surgery is the only option today that effectively treats morbid obesity in people for whom more conservative measures such as diet, exercise, and medication have failed.
There are several types of gastric bypass procedures, but all of them involve bypassing part of the small bowel by greater or lesser degrees. For this reason, procedures of this type are referred to as malabsorptive procedures, because they involve bypassing a portion of the small intestine that absorbs nutrients.
Some of these procedures also involve stapling the stomach to create a small pouch that serves as the “new” stomach or surgically removing part of the stomach.
Although a gastric bypass procedure is malabsorptive, it may also be restrictive because the size of the stomach is reduced so that the amount of food that can be eaten is “restricted” due to the smaller stomach. While malabsorptive procedures are more effective in causing excess weight to be lost than procedures that are solely restrictive, they also carry more risk for nutritional deficiencies.
Types of gastric bypass, or malabsorptive, surgical procedures include:
Roux-en-Y gastric bypass (RGB)
Roux-en-Y gastric bypass, the most commonly performed bariatric procedure, is both malabsorptive and restrictive. This surgery can result in two-thirds of extra weight loss within two years. The procedure involves stapling the stomach to create a small pouch that holds less food and then shaping a portion of the small intestine into a “Y”. The “Y” portion of intestine is then connected to the stomach pouch so that when food is being digested it travels directly into the lower part of the small intestine, bypassing the first part of the small intestine (called the duodenum) and the first part of the second section of the small intestine (called the jejunum). The effect of bypassing these sections of the intestine is to restrict the amount of calories and nutrients that are absorbed into the body.
Biliopancreatic diversion (BPD)
A biliopancreatic diversion is both restrictive and malabsorptive, and is a more complicated procedure than the Roux-en-Y procedure. In this procedure a large part of the lower stomach is removed. The small part of stomach that is left is connected directly to the last part of the small intestine. As food is digested, it completely bypasses the duodenum and the jejunum. Because this procedure may result in nutritional deficiencies, it is not as commonly performed.
A variation of the biliopancreatic diversion is a procedure called the duodenal switch. More of the stomach is retained, including the valve that controls the release of food into the small intestine. A small part of the duodenum is also retained.
The digestive system:
Digestion is the process by which food and liquid are broken down into smaller parts so that the body can use them to build and nourish cells. Digestion begins in the mouth, where food and liquids are taken in, and is completed in the small intestine. The digestive tract is a series of hollow organs joined in a long, twisting tube from the mouth to the anus.