The gastric bypass is presently the most common operation in the United States. This operation was initially developed using an open technique (making an incision where tissues and organs are fully exposed). However, since the mid-1990s, this procedure has been performed using a minimally invasive laparoscopic technique in which the surgery is performed through a series of small incisions. In the last 10 years there have been many modifications made to the procedure as new technologies have evolved.
This operation involves two steps. First, the stomach is divided into two parts. A small stomach pouch is created that receives food from the esophagus. This becomes the patient’s new stomach. The larger remaining stomach is left behind and drains normally into the small bowel. Secondly, the small bowel is divided downstream. The cut end of the small bowel is then brought up and attached to the new stomach so that it may empty. This is the so-called “Roux Limb.” The small bowel is also reconnected downstream to allow for drainage of the unused stomach and proximal small bowel.
How does this operation work?
The gastric bypass operation works for three reasons. First, because the new stomach is very small, it limits or restricts the amount of food that you can eat. Secondly, there is a hormone called Grehlin that is produced in the unused part of the stomach that affects appetite. Because this stomach is not used, the hormone level falls very low and patients generally lose their appetite for a period of 9-12 months. Finally, patients who have this surgery get “dumping syndrome” when they eat sweets. Dumping syndrome occurs when the undigested contents of your stomach enter your small intestine too quickly resulting in abdominal cramps and nausea. Consequently, as a form of aversion therapy, this operation helps patients make better food choices. It has very predictable results and one can expect to lose 60-80% of their excess body weight over the first year after surgery.
Short-term risks include anastomotic (at the site of the bypass connection) complications. Long-term risks include anastomotic strictures, ulcers, fistulas and internal hernias.
The laparoscopic gastric bypass is a difficult operation with significant short and long-term complications and a mortality rate of about 1/1000. It does result in considerable weight loss.