The gastric bypass is a combined procedure consisting of a reduction of food volume and changing the type of digestion. The greater part of the stomach is close-sutured and remains in the body, alongside with the duodenum and part of the small bowl, it is excluded from the food passage.
The food goes from the smaller pouch or "pre-stomach" directly into the small bowl, this deviation is called bypass.
The more common name Roux-en-Y-bypass (YRGB) derives from the similarity of the anastomosis on the lower part of the small bow with the letter 'Y'. Roux was a swiss surgeon who described and performed this kind of anastomosis in another kind of gastrectomy. Thats why the gastric bypass is often named Roux-en-Y-gastric bypass.
The possible weight loss by gastric bypass is higher compared to procedures working just on a restrictive basis. From the excessive body weight, averagely 60% can be lost. A common side-condition of obesity is diabetes type II. After undergoing gastric bypass, many patient can reduce their insulin doses dramatically, in some cases, the diabetes even may resolve. Studies have shown, that the other comorbidities improve as well as the quality of life.
Every operation has its risks, in rare cases there might be even complications. Your surgeon will explain all the benefits and possible disadvantages and risks to you. You will have enough time to reconsider so you can give your informed consent.
Being a major surgery and having a more dramatic influence on digestion, there might be a lack of key vitamins and other trace elements due to malabsorption. It might be necessary to take vitamin pills in shots on a regular basis for the rest of the life.
The excluded part of the digestive system can not easily be assessed by endoscopy or radiology using contrast agents.
One phenomenon that might occur is "dumping". It is caused by osmotic relevant fluids or food such as highly sugared beverages. Because they're are piped directly into the small bowl, they can draw water from the surrounding tissue and the blood vessel system. Nausea, diarrhea and sweating might be the result, sometimes accompanied by heart symptoms like tachycardia. Although in general, this is not a major issue, it makes you feel very uncomfortable. After gastric bypass operation you should avoid such situations by sticking to your diet plan.