BPD removes approximately 3/4 of the stomach to produce both restriction of food intake and reduction of acid output. Leaving enough upper stomach is important to maintain proper nutrition. The small intestine is then divided with one end attached to the stomach pouch to create what is called an "alimentary limb." All the food moves through this segment, however, not much is absorbed. The bile and pancreatic juices move through the "biliopancreatic limb," which is connected to the side of the intestine close to the end. This supplies digestive juices in the section of the intestine now called the "common limb." The surgeon is able to vary the length of the common limb to regulate the amount of absorption of protein, fat and fat-soluble vitamins.
RYGBP-E is an alternative means of achieving malabsorption by creating a stapled or divided small gastric pouch, leaving the remainder of stomach in place. A long limb of the small intestine is attached to the stomach to divert the bile and pancreatic juices. This procedure carries with it fewer operative risks by avoiding removal of the lower 3/4 of the stomach. Gastric pouch size and the length of the bypassed intestine determine the risks for ulcers, malnutrition and other effects.
This procedure is a variation of BPD in which stomach removal is restricted to the outer margin, leaving a sleeve of stomach with the pylorus and the beginning of the duodenum at its end. The duodenum, the first portion of the small intestine, is divided so that pancreatic and bile drainage is bypassed. The near end of the "alimentary limb" is then attached to the beginning of the duodenum, while the "common limb" is created in the same way as described above.