A surgical procedure in which the two parts of the intestine are attached to each other in a Y shape is called roux-en-Y. It can be performed in any part of the intestinal tract but is most commonly performed around the stomach.
In cases of severe obesity, a roux-en-Y procedure may be performed in which the small intestine forms the lower arm of the Y, one of the upper arms of the Y is attached to the top of the stomach and the lower end of the stomach is attached to the side of the small intestine. The stomach itself is cut across and divided into two separate pouches, with food entering only the small upper pouch. This makes the stomach smaller so that only a small amount of food can be swallowed, and the food bypass the stomach and so is not as well digested.