an incision should the need arise. The Roux-en-Y laparoscopic gastric bypass, first performed and reported on in case studies between 1993-1994, is regarded as one of the most difficult procedures to perform by limited access techniques. The use of this method has greatly popularized the operation due to associated benefits such as: a shortened hospital stay, reduced discomfort, shorter recovery time, less scarring, and minimal risk of incisional hernia. Essential features The gastric bypass procedure consists of: Creation of a small, (15–30 ml/1–2 tbsp) thumb-sized pouch from the upper stomach, accompanied by bypass of the remaining stomach (about 400 ml and variable). This restricts the volume of food which can be eaten. The stomach may simply be partitioned (like a wall between two rooms in a house or two office cubicles next to each other with a partition wall in between them—and typically by the use of surgical staples), or it may be totally divided into two separate/separated parts (also with staples). Total division (separate/separated parts) is usually advocated to reduce the possibility that the two parts of the stomach will heal back together ("fistulize") and negate the operation. Re-construction of the GI tract to enable drainage of both segments of the stomach. The particular technique used for this reconstruction produces several variants of the operation, differing in the lengths of the small intestine used, the degree to which food absorption is affected, and the likelihood of adverse nutritional effects. Usually, a segment of the small bowel (called the ) is brought up to the proximal remains of the stomach. Variations Gastric bypass, Roux-en-Y (RYGB, proximal) This variant is the most commonly employed gastric bypass technique, and is by far the most commonly performed bariatric procedure in the United States. The small intestine is divided approximately below the lower stomach outlet and is re-arranged into a Y-configuration, enabling outflow of food from the small upper stomach pouch via a "Roux limb". In the proximal version, the Y-intersection is formed near the upper (proximal) end of the small intestine. The Roux limb is constructed using of the small intestine, preserving the rest (and the majority) of it from absorbing nutrients. The patient will experience very rapid onset of the stomach feeling full, followed by a growing satiety (or "indifference" to food) shortly after the start of a meal. Gastric bypass, Roux-en-Y (RYGB, distal) The small intestine is normally in length. As