The Roux-en-Y laparoscopic gastric by-pass (GBP) is today considered the gold standard operation for the treatment of pathological obesity in the USA. The reasons behind its effectiveness are not clearly understood as it is partly a restrictive procedure and partly relies on the malabsorption of food. Malabsorption allows the patient’s body to absorb only a part of the calories consumed. The malabsorption action created by the GBY operation is relatively mild thus reducing the deficit of vitamin absorption and dumping commonly associated with techniques based purely on malabsorption such as biliary pancreatic diversion or the duodenal switch procedure.
The restrictive action is guaranteed by the creation of a very small gastric pouch which can hold only a very limited amount of food. It is likely that other mechanisms, as yet unknown, are also called into play by the GBP procedure and probably an important role is played by biomolecular substances which regulate the satiety centres. One of the many molecules involved in this aspect is ghrelin, a substance produced in the stomach which triggers appetite. In patients who have undergone GBP it has been seen that blood levels of this molecule drop over time.
This type of operation has proved effective not only in terms of weight loss but also in terms of keeping weight off, although patients who fail to stick to rules governing diet and lifestyle may after a number of years regain some of the weight lost.
In the gastric by-pass procedure, the stomach is completely divided into two using a special stapler so that the upper portion of the stomach is transformed into a very small pouch which is then joined up to the small intestine. Further intestinal joins ensure that the bile and pancreatic juices come into contact with the food further down. One limit to GBP is that it makes it impossible to endoscopically explore the residual stomach which may be a potential seat for the onset of gastric cancer.  Consequently international protocol envisages a pre-operative endoscopic examination of the stomach. However, some scientific research would appear to prove that by-passing the stomach so food does not pass through it (the main characteristic of GBP) may in actual fact prove to be a protective factor against the onset of stomach cancer. After the GBP operation the stomach can in any case still be examined using non-invasive three-dimensional imaging techniques. The decision not to remove the residual stomach is linked to the remote possibility of reconnecting the gastric pouch to the by-passed stomach at some later date.
The GBP procedure is usually carried out laparoscopically. This minimally invasive treatment offers certain advantages such as: a reduction in the risk of post-operative infection and incisional hernia, less pain which in turn leads to faster recovery and shorter hospitalization.


In many patients GBP surgery reduces and solves many of the comorbidities associated with obesity:

  • hypertension (resolved in 69% of cases)
  • metabolic syndrome (80%)
  • type II diabetes (82-98%)
  • hypercholesterolemia (63%)
  • asthma (69%)
  • migraine (57%)
  • depression (57%)
  • non-alcoholic fatty liver disease (90%)
  • gastroesophageal reflux disease (72%)
  • obstructive sleep apnoea (74-98%)
  • osteoarthritis and degenerative articular diseases (41%)
  • venous insufficiency (91%)
  • gout (72%)
  • polycystic ovary syndrome:
  • hirsutism (79%)
  • menstrual irregularities (100%)
  • effort incontinence (44%)
  • many patients maintain a 60 - 70 % loss of their excess weight for 10 years
  • less follow-ups required compared to gastric banding
  • no implants required
  • better mobility and quality of life
  • quicker weight loss compared to gastric banding
  • Dumping Syndrome is a useful deterrent and encourages patients to consume less food and high-calorie drinks
  • no body parts are actually removed.

The aforementioned advantages associated with GBP also contribute to lower mortality rates compared to obese patients who do not undergo surgery.

  • This procedure involves a higher number of complications compared to other techniques (gastric banding) due to the intestinal suturing involved.
  • The peri-operative mortality is higher (0.5% ) compared to banding (0.15%).
  • The reduced portion of the digestive-absorptive tract may lead to nutritional deficiencies consequently patients need to take oral food supplements such as iron, vitamins and calcium.
  • Theoretically the operation is reversible but it is surgically difficult to restore the normal anatomy of the digestive tract.
  • Recovery times are slightly longer than those expected for gastric banding.

Most patients do not suffer from complications following laparoscopic gastric by-pass surgery, however complications may arise and these generally depend on the overall state of the patient’s health. Complications may be of a medical or surgical nature or directly linked to the gastric by-pass itself. Medical complications are associated with the use of anaesthetics and the overall conditions of the patient and may include: bleeding, cardiac arrest, stroke, renal insufficiency, pneumonia, pulmonary embolism, deep vein thrombosis, cystitis and allergic reactions. Surgical complications may be: gastric or intestinal fistula (2-5%), digestive haemorrhage (1-3%), anastomotic stenosis (0.5-2%), damage to adjacent abdominal organs which may need to be removed (e.g. spleen), internal hernia, incisional hernia and early or late intestinal occlusions. Complications linked directly to the gastrointestinal reconstruction performed during the GBP include Dumping Syndrome, vomiting, diarrhoea, the formation of gall stones, vitamin deficiency, electrolyte imbalance, gastric ulcer and anaemia due to malabsorption of iron.


GBP is an extremely effective procedure not only in terms of weight loss but also in terms of the reduction in comorbidities linked to obesity.
Unlike  techniques based purely on malabsorption (biliary pancreatic diversion), GBP creates less problems linked to deficits in intestinal absorption.
For patients undergoing GBP the loss of excess weight is estimated to be around 60 - 70%.