Often referred to as simply a 'duodenal switch' procedure, this particular form of bariatric surgery is in fact a vertical sleeve gastrectomy to which a duodenal switch is added. This procedure is also sometimes referred to as a biliopancreatic diversion with duodenal switch.
Of all of the different forms of weight loss surgery available today this is perhaps the most controversial and, though widely performed, there are many surgeons who will vertical dividers not carry out the procedure because of concerns about its long-term effects on a patient's health.
The first part of the procedure is a vertical sleeve gastrectomy in which the stomach is divided vertically and approximately eighty-five percent is removed. The small remaining 'sleeve shaped' stomach, which retains the original outlet to the intestines, functions very much as a normal stomach and this part of the surgery is designed purely to restrict the quantity of food which can be consumed. This part of the operation is a form of 'restrictive' surgery and cannot be reversed.
The second phase of the operation is to create a duodenal switch and this is a form of 'malabsorption' surgery which is largely reversible. Whereas restrictive surgery creates weight loss by physically preventing the patient from eating too much food, malabsorption surgery is designed to restrict the body's ability to absorb calories from a meal as it passes through the digestive tract.
During the procedure the intestine is divided and a small section (usually about 150 cm in length) is used to create a bypass from the duodenum, which is close to the stomach outlet, to a point near the end of the intestinal tract, thus bypassing the bulk of the digestive tract (typically about 500 cm will be bypassed). The result of this bypass (or duodenal switch) is that food passing through the intestine will only mix with the body's digestive juices in the short final section of the intestine below the switch, giving the digestive juices very little time to digest the food and absorb calories from it into the body.
While duodenal switch weight loss surgery has the advantage of providing the patient with weight loss through both restriction and malabsorption, it is the degree to which the malabsorption element predominates in the duodenal switch which gives rise to much of the controversy surrounding this form of surgery. By comparison, the traditional Roux-en-Y operation has a much shorter bypass and the distance over which food mixes with the digestive juices in the intestine is in the region of five times greater.
The argument which many surgeons use against the duodenal switch is simply that so little absorption takes place that there is too great a risk of anemia, protein deficiency and metabolic bone disease. The vertical sleeve gastrectomy with duodenal switch is also arguably the most complex form of weight loss surgery and many believe that it carries an unacceptably high risk of complications.