The gastric bypass procedure
Gastric bypass is one of the most common types of bariatric surgery. Many surgeons prefer gastric bypass surgery because it generally has fewer complications than do other weight-loss surgeries. that helps you lose weight by changing how your stomach and small intestine handle the food you eat. After the surgery, your stomach will be smaller. You will feel full with less food. The food you eat will no longer go into some parts of your stomach and small intestine that absorb food.
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 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 alimentary limb) is brought up to the proximal remains of the stomach.
Gastric bypass, Roux en-Y (RYGB, proximal)
Graphic of a gastric bypass using a Roux-en-Y anastomosis. The transverse colon is not shown so that the Roux-en-Y can be clearly seen. The variant seen in this image is retrocolic, retrogastric, because the distal small bowel that joins the proximal segment of stomach is behind the transverse colon and stomach.
Illustration of Roux-en-Y gastric bypass surgery
This variant is the most commonly employed gastric bypass technique, and is by far the most commonly performed bariatric procedure worldwide. The small intestine is divided approximately 45 cm (18 in) 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 80–150 cm (31–59 in) 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 6–10 m (20–33 ft) in length. As the Y-connection is moved further down the gastrointestinal tract, the amount available to fully absorb nutrients is progressively reduced, traded for greater effectiveness of the operation. The Y-connection is formed much closer to the lower (distal) end of the small intestine, usually 100–150 cm (39–59 in) from the lower end, causing reduced absorption (malabsorption) of food: primarily of fats and starches, but also of various minerals and the fat-soluble vitamins. The unabsorbed fats and starches pass into the large intestine, where bacterial actions may act on them to produce irritants and malodorous gases. These larger effects on nutrition are traded for a relatively modest increase in total weight loss.
Mini-gastric bypass (MGB)
A mini gastric bypass creates a long narrow tube of the stomach along its right border (the lesser curvature). A loop of the small gut is brought up and hooked to this tube at about 180 cm from the start of the intestine
Numerous studies show that the loop reconstruction works more safely when placed low on the stomach, but can be a disaster when placed adjacent to the esophagus. Today thousands of “loops” are used for surgical procedures to treat gastric problems such as ulcers, stomach cancer, and injury to the stomach. The mini gastric bypass uses the low set loop reconstruction and thus has rare chances of bile reflux.
The MGB has been suggested as an alternative to the Roux en-Y procedure due to the simplicity of its construction, and is becoming more and more popular because of low risk of complications and good sustained weight loss. It has been estimated that 15.4% of weight loss surgery in Asia is now performed via the MGB technique.
Endoscopic duodenal-jejunal bypass
This technique has been clinically researched since the mid-2000s. It involves the implantation of a duodenal-jejunal bypass liner between the beginnings of the duodenum first portion of the small intestine from the stomach, the secondary stage of the small intestine. This prevents the partially digested food from entering the first and initial part of the secondary stage of the small intestine, mimicking the effects of the biliopancreatic portion of Roux en-Y gastric bypass surgery. Despite a handful of serious adverse events such as gastrointestinal bleeding, abdominal pain, and device migration — all resolved with device removal — initial clinical trials have produced promising results in the treatment’s ability to improve weight loss and glucose homeostasis outcomes.
Gastric bypass can provide long-term weight loss. The amount of weight you lose depends on your type of surgery and your change in lifestyle habits. It may be possible to lose 60 percent, or even more, of your excess weight within two years.