While these operations also reduce the size of the stomach, the stomach pouch created is much larger than with other procedures. The goal is to restrict the amount of food consumed and alter the normal digestive process, but to a much greater degree. The anatomy of the small intestine is changed to divert the bile and pancreatic juices so they meet the ingested food closer to the middle or the end of the small intestine. With the two approaches discussed below, absorption of nutrients and calories is also reduced, but to a much greater degree than with previously discussed procedures. Each of the two differs in how and when the digestive juices (i.e. bile) come into contact with the food.
Because food bypasses the duodenum, all the risk considerations discussed in the gastric bypass section regarding the malabsorption of some minerals and vitamins also apply to these techniques, only to a greater degree.
Biliopancreatic Diversion (BPD) completely removes the approximately three-quarters of the stomach, retaining the natural stomach outlet, to produce both restriction of food intake and reduction of acid output. 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.” This separates digestive juices until they join at the “common channel.” 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.
Biliopancreatic Diversion with “Duodenal Switch” (BPD_DS) 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 intact. 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.” This separates digestive juices until they join at the “common channel.”
- Patients are able to eat larger meals than with a purely restrictive or standard Roux-and-Y Gastric Bypass procedure.
- Can produce the greatest excess weight loss because it provides the highest levels of malabsorption.
- In one study of 125 patients, excess weight loss of 74% at one year, 78% at two years, 81% at three years, 84% at four years, and 91% at five years was achieved.
- Long-term maintenance of excess body weight loss can be successful if the patient adapts and adheres to a straightforward dietary, vitamin supplement, exercise, and behavioral regimen.
(The following are in addition to the general risks of surgery.)
- For all malabsorption procedures, there is a period of intestinal adaptation when bowel movements can be very liquid and frequent. This condition may lessen over time, but may be a permanent lifelong occurrence.
- Abdominal bloating and malodorous stool or gas may occur.
- Closing lifelong monitoring for protein malnutrition, anemia and bone disease is recommended. Intravenous replacement of deficiencies are often necessary lifelong with cost implications. If the patients do not follow up regularly they might developed severe malnutrition and may even die.
- Lifelong vitamin supplementing is required. If eating and vitamin supplement guidelines are not rigorously followed, at least 25% of patients will develop problems that require treatment.
- Changes to the intestinal structure can result in the increased risk of gallstone formation and the need for removal of the gallbladder.
- Rerouting of bile, pancreatic and other digestive juices beyond the stomach can cause intestinal irritation and ulcers.
- When removing or bypassing the pylorus, a condition known as “dumping syndrome” can occur as the result of rapid emptying of stomach contents into the small intestine. This is sometimes triggered when too much sugar or large amounts of food are consumed. While generally not considered to be a serious risk to your health, the results can be extremely unpleasant and can include nausea, weakness, sweating, faintness, and on occasion, diarrhea after eating.
- Increased surgical risks.