The DS works by gastric restriction in addition to malabsorption. Anatomically, mainly the difference between DS and BPD is how the stomach is shaped - the malabsorptive part is basically identical to the BPD. Compared to BPD, DS creates a much smaller stomach that will create a restricted feeling a lot like a RYGBP. Rather than cutting the stomach horizontally and taking the lower half away (such as occurs with the BPD), the duodenal switch makes an incision in the stomach vertically and leaves a stomach tube that empties it into a really short segment of the duodenum.

The duodenum is tolerant of the acid in the stomach and thus is a lot more resistant to ulceration in comparison to the small intestine. Removing a portion of the stomach also inhibits the amount of acid that is present in the abdomen. Whereas the BPD includes a connection, or anastomosis between the intestine and stomach, the DS includes an anastomosis between the intestine and duodenum.

The singular duodenal switch procedure was initially devised by Tom R. DeMeester, M.D. for the purpose of treating bile gastritis, a condition in which the abdomen and esophagus get burned by bile. In 1988, Dr. Douglas Hess of Bowling Green, Ohio, became the first doctor to combine the DS with BPD.

A theoretical, although clinically unproven, benefit of the duodenal switch is an improvement of the absorption of iron and calcium when you compare it to the BPD. The disadvantage of severing the duodenum is the large amount of vital structures that are in very close proximity and adjacent to the duodenum. Many large blood vessels and the essential bile duct are located here. Injury or trauma to these areas could be life-threatening.

These operations have some of the highest reported weight loss results, in terms of long-term studies. On the other hand, they also have the biggest rate of nutritional complications when compared to the RYGBP and the other entirely restrictive procedures. These procedures are some of the most complex bariatric surgeries to perform. Although, like most weight loss surgery studies, there is a wide variability for long-term results among different centers or practices.

Some surgeons and patients believe that the duodenal switch is a preferable operation to the RYGBP and BPD because of patients not having to experience the "dumping syndrome", described above. The duodenal switch and BPD have their own particular side effects, though. After a high fat meal, people may experience bad smelling gas and diarrhea.

Take your time finding someone you can trust, and feel comfortable with, to perform this procedure for you. Make sure it's a highly qualified health professional with expertise in the specialty you are interested in.

This procedure, also known as the biliopancreatic diversion with duodenal switch (or the Distal Gastric Bypass with Duodenal Switch), solves a lot of nutritional problems related to other forms of WLS, and enables a good eating quality compared to other WLS procedures.