Gastric bypass (to be more precise, gastric Rous-en-Y bypass) is a very common weight loss method in bariatric surgery. The name comes from the name of the Swiss surgeon Rous who has developed the basic surgical technique. "Y" is used in the name because of the shape in which the pieces of the intestine are joined together, namely the shape of the letter Y.
There are two principles on which the success of gastric bypass surgery is based:
- Stomach reduction resulting in a reduction in the amount of food (restriction)
- Disconnecting the important upper part of the small intestine (duodenum), so that digestive juices that are important for food breakdown join the food mass much later (lack of nutrient absorption = malabsorption)
Weight loss after gastric bypass is very effective and reliable, but there are some permanent restrictions. A patient who has undergone Rous-en-Y gastric bypass surgery can eat only very little food, as the remaining small stomach is very small after surgery. Nutrient absorption decline causes patients to take certain dietary supplements and vitamins (especially vitamin B 12, micro-nutrients and protein) throughout their life in order to prevent symptoms of inadequate absorption. As some nutrients remain undigested, the process of gas formation may increase in the large intestine. After a successful weight loss, the operation cannot be reversed.
Preparation for Gastric Bypass Surgery
Before the surgery, it is necessary to make sure that there are no pathological changes in the stomach. For example, the stomach is checked for the presence of diseases, such as gastritis or stomach ulcer, and for the probable presence of Helicobacter pylori bacteria colonies which are likely to cause stomach ulcers. In addition to gastroscopy and gastric acid secretion tests, ultrasound of the epigastric area is also performed to detect gallstones. During gastric bypass, they should be removed immediately, as they can lead to inflammation of the gallbladder and biliary tract.
How the Operation Proceeds
Depending on the patient, gastric bypass surgery takes approximately from 90 to 150 minutes and is performed under general anesthesia. The intervention usually requires a hospital stay of about one day before the operation (preparation for surgery and anesthesia) plus from five to seven days after it. After gastric bypass, the patient is not able to work for about three weeks.
Gastric bypass is now practically always performed in a minimally invasive way. When this technique, also called "keyhole surgery", is performed, instruments and a small camera are inserted into the abdominal cavity through several incisions approximately two centimeters long. Minimally invasive operations involve lower surgical risks in general than open surgery and are therefore particularly suitable for obese patients who already have a high risk of complications during and after surgery.
Gastric bypass procedure consists of several steps:
- After giving general anesthesia, the surgeon inserts instruments and a camera with a lighting source into the abdomen through several incisions. The abdominal cavity is then filled with gas (usually CO2) to make the abdominal wall slightly higher than the organs and to give the surgeon more space in the abdominal cavity and a better view of the organs.
- Then, the stomach is separated below the esophagus with the so-called stapler. The stapler cuts and sutures at the same time, so that the incision is immediately closed. In this way, a small stomach remains at the end of the esophagus. It has a capacity of no more than 50 milliliters. Although the stomach remains in the body, its upper end is sutured, and thus it is "decommissioned" in a sense.
- The next step is to shut down the small intestine in the jejunum. The lower end of the intestine is pulled up and sutured to the small stomach. For this reason, this connection is also called gastrojunal anastomosis.
- Then the remaining free end of the jejunum is sutured even lower with the third part of the small intestine (the iliac), so that there is a Y shape (Y-anastomosis). This is where the digestive juices from the duodenum (bile and pancreatic secret) mix with the food mass.
Who Gastric Bypass is Suitable for
Gastric bypass is suitable for people with a body mass index (BMI) of over 40 kg/m² (obese stage 3 or morbid obesity). However, the prerequisite for gastric bypass is that all non-surgical measures have not been effective enough within 6-12 months. These measures include, for example, professional nutrition counseling, physical exercise and behavioral psychotherapy (multimodal obesity treatment concept). Gastric bypass can be performed between the ages of 18 and 65, although in some cases the operation can be performed on older or younger people.
Gastric bypass is particularly recommended for people whose overweight is caused primarily by high calorie intake (sweets, fatty foods) and sweet drinks. As they are now less digestible, the body can absorb and retain a small proportion of them as body fat.
If there are already metabolic disorders (metabolic diseases) such as diabetes mellitus, hypertension or obstructive sleep apnoea because of the excess weight, it is reasonable to perform gastric bypass surgery with an IMT of 35 kg/m².
Who Gastric Bypass is not Suitable for
Various physical and mental illnesses mean that bariatric surgery, including gastric bypass surgery, is prohibited. First of all, in the case of earlier surgeries and gastric, peptic and addictive disorders, as well as incurable eating disorders such as bulimia, gastric bypass surgery cannot be performed. Pregnant women should not undergo gastric bypass surgery either.
Effectiveness of Gastric Bypass
Gastric bypass is very effective, however, only a few patients attain normal weight (BMI ≤ 25 kg/m²). Studies have shown that gastric bypass can result in a long-term loss of approximately 60-70% of excess weight, i.e. the amount of weight surplus that keeps a person away from normal weight.
In addition to a merely cosmetic effect, the loss of weight after gastric bypass has a positive effect on metabolism. For example, in many cases, the intervention is very helpful in diabetes mellitus and sometimes even cures it completely. In many cases, the blood glucose level drops a little after the operation, although the amount of weight loss is still insignificant. The reasons for this are not yet completely clear. Various hormonal changes (e.g. secretion of the ghrelin hormone, glucagon, GIP, etc.) are believed to occur as a result of the operation and to have a positive effect on metabolic rate.
Advantages of Gastric Bypass over Other Techniques
Since gastric bypass surgery is a combination of two principles (restriction and malabsorption, see above), the technique is highly effective and works well especially when patients are overweight because of excessive consumption of high-calorie liquids and soft foods. For the so-called sweet tooth, just a reduction in the volume of the stomach, which is achieved through gastric banding, stomach ballooning or sleeve gastroplasty, would be insufficient.
Gastric bypass surgery has some side effects. The degree of their manifestation varies individually, and therefore they cannot be predicted accurately. The most serious ones are:
- Digestive disorders caused by malabsorption: flatulence, stomach aches, nausea and bloating.
- Iron deficiency and anemia: usually most of the iron taken out of food is absorbed in the duodenum. Since after gastric bypass food passes past the duodenum, iron absorption is impeded. Iron deficiency is prevented by its supplemental intake.
- Vitamin B12 deficiency (a specific form of anemia): vitamin B12 is absorbed in the end part of the small intestine (in the final part of the ileum). But this requires an auxiliary substance, the so-called internal factor, which is produced by the stomach. But when the stomach is bypassed, the food passes by and therefore less internal factor is produced. In this regard, vitamin B12 is regularly injected intramuscularly or intravenously. There are also preparations with vitamin B12, which should be absorbed straight into the oral mucous membrane (sublingual administration). But there are still disputes about their effectiveness.
- Vitamin D deficiency. It is still unclear why vitamin D deficiency occurs when the stomach is bypassed. Vitamin D can be easily replenished with food (orally).
- Dumping syndrome. Dumping syndrome is a number of symptoms (dizziness, nausea, sweating or heartbeat) that can be caused by a sudden (as if falling) discharge of food from the esophagus into the small intestine, as the small stomach does not have a lower sphincter. The food mass attracts water from the surrounding tissues and blood vessels into the small intestine by osmotic force. This reduces the volume of fluid in the circulatory system, which can cause a drop in blood pressure. Dumping syndrome is particularly common after drinking very sweet drinks or eating fatty foods.
- Peptic ulcer disease of the small stomach. After gastric bypass, the risk of ulcers in the small stomach increases. This is solved by taking acidic medicines, the so-called proton pump inhibitors (PPIs), which should be taken for a long time if there is an ulcer after gastric bypass surgery.
- Loss of muscle mass. Rapid weight loss is often associated with loss of muscle mass, as the body tries to compensate for the relative lack of carbohydrates through the breakdown of its own protein (primarily through the use of least used muscle cells). Regular physical exercise can stop this process. For overweight people, sports that keep joints healthy, such as light weight training, cycling, swimming or aqua-aerobics, are recommended.
Gastric Bypass. Risks and Complications
Gastric bypass surgery is a major abdominal intervention that greatly alters the natural anatomy of the gastrointestinal tract. In fact, surgical risks are insignificant, but as with any surgical intervention, complications cannot be excluded. The non-specific surgical risks include:
- Complications caused by anesthesia
- Damage to organs and blood vessels
- Infection in internal and external sutures
- Lack of sealing in the artificial organ connections (anastomoses) with the risk of abdominal cavity inflammation (peritonitis)
- Disorderly suture fusion
- Peristaltic disorder (intestinal atony)
Gastric Bypass. Nutrition after Surgery
After gastric bypass, people should keep to the following nutrition rules for the rest of their lives to prevent problems with digestion:
- Chew food very carefully
- Eat small portions of food
- Avoid excessively sweet food and drinks
- Take nutritional supplements