Duodenal switch surgery, also known as biliopancreatic diversion with duodenal switch, is a procedure that involves both a gastric sleeve and a bypass of the small intestine. It is a more complex surgery that can lead to more weight loss, but it also carries more risks. During the procedure, the surgeon will remove about 80% of the stomach, creating a sleeve-shaped stomach similar to the gastric sleeve procedure. The remaining portion of the stomach is then connected directly to the lower part of the small intestine, bypassing the upper part of the small intestine. This allows food to bypass a significant portion of the small intestine, reducing the amount of calories and nutrients that are absorbed. Duodenal switch surgery is typically performed through open surgery and takes about four to six hours.