Step One, Gastric Bypass Procedure: Divide Stomach and Jejunum
During the gastric bypass procedure, the upper stomach is divided with a stapler and reinforced with stitches to create the new upper (proximal) stomach pouch. The new pouch is the size of a golf ball, holding about 20 cc. The pouch is made so small for two reasons. First, it will eventually stretch somewhat. By making it very small at first, the final size will still be quite restrictive. Second, the upper pouch continues to make stomach acid. The pouch is kept small to minimize the amount of acid that enters the upper jejunum and thus minimize the chance of developing an ulcer at the stomach jejunum anastamosis.
The lower (distal) larger part of the stomach is left in place for three reasons. First, it still produces acid and pepsin to help digest food. These juices travel down the duodenum and into the jejunum to mix with food. Second, if for any reason a patient needs to have the operation reversed, the stomach is still there and can be hooked up again. Please note that this is very rarely necessary. Third, removing the lower part of the stomach would greatly prolong the surgery and make it more dangerous.
The upper jejunum is also divided in preparation for bringing it up to connect to the upper stomach pouch.
Step Two, Gastric Bypass Procedure: Attach Jejunum to Stomach Pouch
The part of the jejunum that is brought up behind the colon and lower stomach pouch is called the "Roux limb". (Roux was a Swiss surgeon who developed the general technique.) The Roux limb is joined or "anastamosed" to the upper stomach pouch using a circular stapler or with a hand sewn technique. The staple line is reinforced where necessary with hand sewn stitches. The opening between the pouch and the intestine is 1.1cm (less than 1/2 inch) in diameter.
Step Three, Gastric Bypass Procedure: Attach Proximal Jejunum to the side of Roux Limb
The end of the jejunum is attached to the side of the Roux limb. Thus, food goes down the esophagus into the upper pouch. It then goes through the anastamosis into the Roux limb. Digestive juices from the stomach, the liver, and the pancreas travel down the duodenum and jejunum and are added to the food that has come down the Roux limb where the two parts of the small intestine are attached. The food and the juices then travel down the small intestine mixed together and further digestion takes place.
Step Four, Gastric Bypass Procedure: Gastrostomy Tube
A gastrostomy tube is occasionally inserted through the left upper abdominal wall into the lower stomach. The tube is a safety device that allows stomach juices to escape if the juices can't drain easily into the small intestine. Most patients don't need the tube, and the decision to place the tube is made at the time of surgery based on how loose or tight the tissues are where the small bowel is attached to the Roux limb. The gastrostomy can cause complications, and it is inconvenient and uncomfortable, so we do not use it routinely. If a gastrostomy tube is inserted, it can easily be removed in the office about 3 weeks after surgery.
This diagram shows a finished gastric bypass operation and includes the formal medical terms that describe the different parts. These terms are shown because they are frequently used in medical articles that you may read on the web or at the library. The operation is called a "Roux en Y Gastric Bypass" because the idea of bringing up the length of small intestine was developed by the Swiss surgeon Roux, the reconstruction in "Y" shaped, and most of the stomach is bypassed!