It may be necessary to practice a surgical procedure that will help produce greater weight losses, even greater than those obtained with a Gastric Bypass when a patient suffers from a very severe obesity (superobesity, BMI > 50 kg/m²), laparoscopic biliopancreatic diversion can be used for these cases.
The size of the stomach is reduced a little with this method, in order to reduce the amount of food that the patient can consume during the first months. Nevertheless, the stomach is much bigger than that of a patient with gastric bypass, allowing him/her intake of normal sized meals during the first months.
Additionally, the stomach is directly connected to the small bowel, as in gastric bypass, but in a section even more distal. This means that when the patient eats, little of this food will be absorbed, leading to a notorious weight reduction with a normal size portion diet (similar to that of a non-operated person). The patient with a biliopancreatic diversion must have an increased protein intake - meat, chicken, fish, and egg-. Since fat absorption is very small, it can be included in the diet with no restriction. It is important to avoid sugar and have a low alcohol intake in order to have an adequate weight loss.
The decrease in the absorption of some food makes the patient have more frequent bowel evacuation (2-4/day). Just as with the gastric bypass, patients will need to take vitamins and minerals permanently after surgery, and keep in close control with the obesity clinic's dietitian to avoid deficiencies of some sort due to the poor absorption of some types of food. This surgery is preferred for patients with superobesity (BMI>50 kg/m²) and for patients who find it very hard to stick to a reduced portion diet. After biliopancreatic diversion patients can have normal size portions in their diet.
Two types of biliopancreatic diversion are used at the moment: Scopinaro's biliopancreatic diversion and the one with duodenal switch. They differ little in the type of changes practiced to the stomach, but both have similar outcomes. In this type of surgery not only are normal connections of the stomach to the intestine altered, but part of the stomach is taken out (see figures).
Advantages of laparoscopic biliopancreatic diversion.
It is a minimally invasive surgical procedure since it is done through laparoscopy. After this surgery, patients can have a diet very similar to his/her usual. Simple carbohydrates (sugar, sweets and chocolate) must be avoided. Tolerance to normal food is good and portions are similar to those taken by a normal size person without surgery, since the weight loss is mainly achieved by the poor absorption of some foodstuff.
This is the reason why it is the surgical procedure by excellence for patients with extreme obesity and for those with difficulty in following diets.
It is the surgery that produces better long lasting weight decrease, associated to an unrestricted diet. The patient can obtain a reduction of up to 85% of their overweight. This weight loss is obtained with little changes in the diet, making it a method easily accepted by the patient.
Risks in biliopancreatic diversion.
After this procedure patients have an increase in the frequency of bowel movements. There is a higher risk of suffering from diarrhea than with any of the other bariatic procedures. Since food is eliminated without digestion, many patients have foul-smelling stools and flatulence. There is risk of bone demineralization and micronutrient deficiency - the patient must take permanently calcium and vitamins to avoid it-, as well as vitamin B12 which must be injected every 3 - 4 months or taken orally.
This method brings a higher risk for malnutrition than the gastric bypass. The diet of the patient with a biliopancreatic diversion is very different to that of a patient with a gastric bypass. These patients must have a high protein intake (meat, chicken, fish, eggs, etc.), similar to what they used to eat before the operation. In case malnutrition appears that does not correct with a nutritional treatment, it can be overcome with a laparoscopic procedure to increase the absorption. This is achieved by connecting the intestine to a more proximal portion than the initial procedure.
Overall, the advantages of the biliopancreatic diversion outweigh the risks, and this operation can be practiced in patients with a body mass index greater than 40 kg/m² who have other medical problems associated to their obesity (hypertension, diabetes, etc). This procedure is considered particularly useful for patients with a BMI greater than 50 kg/m² or those with difficulty to stick to restrictive diets and wish a normal one.