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Gastric bypass

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The procedure

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The gastric bypass operation (Roux-en-Y gastric bypass) consists of two parts: In the first part of the operation, a small gastric pouch or gastric reservoir ('stomach pouch') with a volume of about 10 - 30 ml is created by means of a stapler. The remaining part of the stomach is not removed. In the second part of the operation the small bowel is transsected approximately 30-45 cm from it's origin and this segment of small bowel is connected to the gastric reservoir. Then, the small bowel (alimentary small intestine loop) is reconnected 120 cm further to the other segment of small intestine (biliary loop) so that both segments of small bowel are connected in the shape of a 'Y'. Hence the name 'Roux-en-Y'. At this level, where both pieces of small bowel are reconnected (i.e. 120 cm after the connection with the gastric pouch), the food and the digestive juices join together. Hence the name, 'bypass', because most of the stomach and duodenum are 'bypassed'. This procedure is performed through keyhole (laparoscopic) surgery.

Mechanism of action

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There are several mechanisms of action that explain the weight loss after a gastric bypass:

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  • Due to a smaller stomach volume of the stomach pouch, a feeling of satiety is obtained more quickly.

  • Because of the faster food transition from the stomach pouch directly into the small intestine and because the duodenum is 'bypassed', there is an increase in the 'incretin' hormones , which in turn cause a feeling of satiety. Moreover, it are these 'incretin' hormones that have a direct beneficial effect on type 2 diabetes through better control of the sugar metabolism.

  • Because the food in the first part of the small intestine only comes into contact with the digestive juices after 120 cm, some of the fats and sugars are absorbed less well (malabsorption) , which means that some of the calories are not absorbed.

  • The operation also changes the distribution and concentration of a number of gut bacteria (microbiome) , which in themselves also play a role in weight loss.

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Weight loss

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Long-term results show that after a gastric bypass an average weight loss between 52% and 68% of the overweight (%EWL*) is achieved.

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Exactly how much weight is lost after surgery varies between individuals and depends on gender, age, weight before surgery and the compliance of follow-up after surgery. In our experience it is clear that optimal follow-up leads to increased motivation and better results in the long term. In particular, the extent to which the dietary recommendations are followed and the degree of physical activity determine long-term success.

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Most of the weight loss occurs in the first 12 to 18 months after the procedure. This is usually followed by a slight weight increase of a few kg, after which the weight stabilizes again. Especially in this period (after the so-called

'honeymoon' months) thorough follow-up is crucial. 

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* %EWL = % Excess Weight Loss = weight loss/(starting weight – ideal weight calculated on a BMI of 25))

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Potential complications

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In the short term , the following complications can occur:

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  • Woundinfection/wound abscess.

  • Leakage or bleeding at the junction between the stomach and the small intestine (Anastomotic leakage)

  • Blood clot in the legs and/or lungs (Deep venous thrombosis/Pulmonary embolism)

 

In the long term , the following complications can occur:

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  • Hair loss (this is temporary due to the rapid weight loss and is reversible)

  • Fatigue (mainly in the period with the most weight loss)

  • Incisional hernia (less risk due to the use of the laparoscopic technique)

  • Vitamin deficiencies that require additional supplements.

  • Dumping Syndrome

  • Bowel obstruction: Because the anatomy of the small intestine is altered after a gastric bypass, an 'Internal Herniation' can occur, which means that a part of the small intestine can get stuck through an opening in the intestinal membrane. This causes complaints of abdominal pain (more intense after meals). The risk of an internal herniation varies between 1.4%-10% of patients who have undergone gastric bypass surgery. In most cases, this can be treated easily by a laparoscopic intervention. 

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It should also be taken into account that in female patients, birth controle pills may be less effective after the procedure due to an altered drug absorption. This should be discussed with your gynaecologist .

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Furthermore, pregnancy within 18 months after the procedure is also strongly discouraged. Because of the rapid weight loss ('catabolic' state = the body is braking down its overall mas) the body is not in an optimal state to to be able to form an embryo or fetus at the same time.

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A gastric bypass should be considerd as irreversible . Although from a technical point of view the original anatomy can be restored, the functional results are very poor and this procedure is only performed in very exceptional circumstances.

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Hospital stay

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The first day after the operation a light diet will be initiated and early mobilization is stimulated in order to avoid respiratory complications and to prevent potential blood clots in the legs and/or lungs.  Adequate pain medication is provided. During the hospitalization, the dietitian will provide all the necessary nutritional advice for the first weeks after the operation. When the blood tests and clinical examination are reassuring, most patients can be discharged the first day after surgery. A first wound check with the general practitioner is scheduled after one week. The wounds are sutured with a self-dissolving suture, located within the wound itself, so no stitches need to be removed.

 

When discharged from the hospital, a prescription for the following medication is provided:

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  • Daily injections with blood thinners (LMWHs) to prevent blood clots in the legs and/or lungs for 30 days after the procedure.

  • A proton pump inhibitor (PPIs) to protect the anastomosis or stapler line against stomach ulcers. This should be continued for 3 months postoperatively.

  • Pain medication

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Nutritional advice and physical activity

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The dietician will explain in detail the diet that has to be followed both before the procedure as well as during the hospitalization. An overview of the various postoperative diet phases can be found here.

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In the first weeks it is recommended to stay mobile: walk around sufficiently and resume daily physical activities as much as possible within the limits of potential pain. Heavy exertion should be avoided intially until after the first consultation with the surgeon, 3 weeks after the procedure.

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Alarm Symptoms

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In the case of the following symptoms, you are requested to contact the general practitioner or our department or, if necessary, to go to the emergency department:

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  • Severe abdominal pain

  • Fever

  • Vomiting blood or blood in stool/black stool

  • Inability to take in food.

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Follow-up

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After the operation, follow-up is organised with various members of the multidisciplinary team as well as by your general practitioner. Furthermore, lifelong multivitamine supplements need to be taken. In the first year after the operation, a blood test is also performed at regular intervals to detect any deficiencies in minerals and vitamins. Afterwards, an annual bloodtest is required. 

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