Mini gastric bypass or Brown gastric bypass is a specific type of gastric bypass that creates only one anastomosis (new connection) between the small stomach and the small intestine. For this reason, this type of bypass surgery is also known as one-anastomosis bypass or mini gastric bypass surgery.
During the operation, a small part of the cardiac region is separated from the rest of the stomach. This part is usually considerably longer than the one used in Rous-en-Y gastric bypass surgery and is also called a small stomach. The main part of the stomach, as in the case of Rous-en-Y gastric bypass, is excluded from the digestive process, so this operation is called bypass. The big stomach is left in the body. Mini gastric bypass or Brown gastric bypass can be completely removed if necessary. The small stomach is only connected to the small intestine, so that the food merges with the digestive juices (bile, pancreatic juice) much later. The length of the small intestine, which is excluded from the digestive process, is 200 cm.
The main mechanism of weight loss is limiting nutrition. Hormonal changes (GPP-1 hormone, ghrelin) and moderate malabsorption of fat as a result of bile absorption contribute to weight loss and regulate insulin production. This technique has a pronounced positive effect on the already existing diabetes. Mini gastric bypass or Brown gastric bypass also has a positive effect on other concomitant diseases and factors that lead to atherosclerosis (calcification of blood vessels), such as high blood levels of cholesterol and fats. Long-term data on weight loss indicate that there is an advantage of 10-15% in mini gastric bypass or Brown bypass over Rous-en-Y bypass. The disadvantage of this method is that there is a possibility of bile reflux. The risk of peptic ulcers, including bleeding and stenosis (narrowing) in the anastomosis area between the stomach and the small intestine is relatively high. It is also impossible to completely rule out the mucous membrane dying out as a consequence of prolonged bile irritation. For this reason, it is recommended to use this technique mainly in patients who are over the age of 40. Approximately 10% of all patients who have undergone mini gastric bypass or Brown bypass need revision surgery to eliminate reflux (usually conversion to Rous-en-Y bypass).
Therefore, Rous-en-Y gastric bypass is now regarded to be an established standard in bariatric surgery. Sometimes, during the operation, it is decided to perform mini gastric bypass or Brown bypass instead of the initially scheduled Rous-en-Y bypass. The reason for this may be, for example, the enlarged liver or an overall lack of space in the abdominal cavity during surgery, which can make it difficult to perform a second anastomosis.
Mini gastric bypass or Brown gastric bypass, like Rous-en-Y bypass, is performed laparoscopically, i.e. through 5-6 small punctures in the abdominal wall. As with any bariatric operation, a two-week liquid diet is absolutely necessary before the operation. In this way, the size of the liver is reduced by about 30%. This creates more space in the abdominal cavity, so that the operation is easier and therefore safer for the patient.
Life-long administration of vitamins, micronutrients and minerals (calcium, iron, and magnesium) is definitely necessary to prevent any symptoms of deficiency. It should be noted that some symptoms of deficiency lead to diseases that are sometimes irreversible.