Biliopancreatic diversion (BPD) is the most complex but at the same time the most effective type of obesity surgery. The intervention deliberately triggers nutrients absorption disorder in the small intestine (malabsorption). However, the biliopancreatic diversion is an irreversible intervention, thus the patient needs to take life-long food supplements.
The term "biliopancreatic diversion" refers to the fact that the food pulp is supplied with gall (bile) and pancreas digestive secretions only in the lower part of the small intestine. This hinders the breakdown of nutrients and they are absorbed into the blood in the small intestine in a much smaller amount.
The biliopancreatic diversion usually leads to a particularly significant weight reduction in patients with obesity. Internationally, the biliopancreatic division is regarded as a standard procedure, but it is quite rarely performed in Germany.
The working principle is based primarily on malabsorption, a technical term for poor absorption of nutrients in the intestines, caused by the operation. Normally the food pulp from the stomach is mixed with the digestive enzymes from the pancreas and gallbladder already in the duodenum. Thus the nutrients are broken down and can be absorbed by the intestinal mucosa and passed into the bloodstream.
However, due to the biliopancreatic diversion, the digestive juices are introduced much further down in the small intestine. Only here the food pulp gets mixed with them. Thus, the absorption and the breakdown happens only in a short intestine and for a much smaller time: therefore a large part of the nutrients is passed on undigested further into the colon and is excreted with the stool.
However, the weight reduction results not only from the malabsorption. The second operating principle is the so-called restriction: the stomach is also significantly reduced in the biliopancreatic division. Due to the reduced stomach volume (restriction) it is filled faster and thus making the patient eat less.
In principle, there two alternatives for the operation: the sole biliopancreatic diversion (BPD) and the biliopancreatic diversion with duodenal switch (BPD-DS). In BPD the stomach volume is reduced to approximately 250 to 500 milliliters. In the BPD-DS the stomach is shrunk using a so-called sleeve gastrectomy ("gastric sleeve") to a volume of only about 100 to 120 milliliters. Thus, the restriction in the BPD-DS is even more pronounced than in the sole BPD. Advantageous is that in the BPD-DS the pyloric part (pylorus) is preserved. The food pulp thus does not freely pass from the remaining stomach into the intestine, but moves more slowly and continuously through the pylorus into the intestine. This significantly reduces the risk of a so-called dumping syndrome (see below).
Prior to the procedure a gastroscopic examination is performed in order to exclude serious diseases of the stomach and the duodenum. An ultrasound examination of the abdomen should also be carried out detecting any existing bile secretion disorders, for example, gallstones. If gallstones are discovered, the gallbladder is usually removed during the biliopancreatic diversion as a precaution, since later as the result of the desired weight loss more stones can form, often causing inflammation of the gallbladder and bile duct. Before the operation, a electrocardiogram (ECG) and a pulmonary function examination are also required.
Nowadays the biliopancreatic diversion is mostly performed minimally invasive. This method, also known as the "keyhole technique", does not require a large abdominal incision. Instead, the surgical instruments and a small special camera are introduced into the abdominal cavity through several small skin incisions. Minimally invasive operations generally have a lower surgical risk compared to open surgeries and are therefore particularly suitable for obese patients who already have significantly increased surgical risks.
The biliopancreatic diversion is performed in several steps. While the patient is under the general anesthesia, the surgeon guides the instruments and a camera with a light source through several skin incisions into the abdominal cavity. During the operation, gaseous carbon dioxide is also introduced into the abdominal cavity to separate the abdominal wall from the organs and to give the surgeon a better visibility and more space in the abdominal cavity.
Now the stomach is separated just below the esophagus. This leaves only a small remaining stomach (stomach pouch) left at the end of the esophagus. The remaining parts of the stomach are removed. However during the biliopancreatic diversion with duodenal switch instead of the stomach pouch a so-called tube stomach with significantly smaller volume is formed.
In the next step, the surgeon cuts the small intestine about 2.5 meters before the beginning of the colon. Its lower part is pulled up and sewn directly to the stomach pouch or the stomach sleeve. The upper part of the small intestine is no longer connected to the stomach and is used only to transport bile and pancreatic digestive secretions. The part is guided in the small intestine about 50 centimeters above the colon and sewn together.
Therefore, the whole length of the part of the small intestine, where the food and the digestive juices are mixed, is only about half a meter long instead of several meters. Since this is not sufficient for a complete splitting and absorption of nutritions, these are passed largely undigested into the colon, which in turn doesn't absorbs many nutrients. It serves to thicken the digested food pulp.
The biliopancreatic diversion lasts two to three hours and is always carried out under general anesthesia. The surgery usually requires a hospital stay of about eight days: one preparation day and seven days for close medical observation after the procedure. Usually about three weeks after the operation the patient can resume their professional activity if no complications occur.
The biliopancreatic diversion is a treatment method for obese people with a body mass index (BMI) of ≥ 40 kg/m² (Obesity Grade III). If metabolic diseases, such as diabetes, hypertension or sleep apnea, are caused by obesity, a biliopancreatic diversion can be useful starting from a BMI of 35 kg/m².
The precondition for the biliopancreatic diversion and all other obesity interventions is that all non-surgical measures were unsuccessful for six to twelve months. These measures include professional nutritional advice, exercises and behavioural therapy (a so-called multimodal approach to obesity treatment). To have a biliopancreatic diversion performed one should be at least 18 and not more than 65 years old, in individual cases the operation is also possible in younger or older people.
In the case of patients with extreme obesity (BMI > 50 kg/m²), the operation is sometimes divided into two sub-surgeries: firstly, only the gastric sleeve is created. It helps to reduce the weight and thus minimize the surgical risk of the second intervention (the actual biliopancreatic diversion).
A malabsorptive procedure such as biliopancreatic diversion is particularly recommended for people who can not change their unfavorable eating habits. While these people cannot reduce weight using other methods (such as sleeve gastrectomy or gastric banding), a biliopancreatic diversion due to the malabsorption can promise effective weight reduction, even with unfavorable eating habits.
There are many physical and mental disorders that speak against an obesity operation such as the biliopancreatic diversion (contraindications). In particular, previous surgeries and malformations of the stomach or intestine are important contraindications for a biliopancreatic diversion. Psychic comorbidities such as addiction or untreated eating disorders (e.g. binge eating or bulimia) are other exclusion criteria for the procedure. Whether you are suitable for a biliopancreatic diversion or not, you will find out in a conversation with the surgeon.
The biliopancreatic diversion is the most effective surgical procedure for the weight loss. Studies show that the loss of excessive weight (excess weight loss = EWL) amounts to 52 percent in the sole BPD and 72 percent in the BPD-DS. In addition to the purely cosmetic and psychologically relieving effect, the weight loss after the surgery also positively influences the patient's metabolism. For example, in many cases, an existing diabetes is greatly improved and sometimes even completely cured. The blood glucose levels often normalize shortly after the operation, even though the patient has not yet significantly lost weight. The reasons for this are not fully understood. Some researchers suspect that altered gastrointestinal passage trigger different hormonal changes, which have a favorable effect on energy metabolism.
Since the effect of the biliopancreatic diversion is based on two different principles (restriction and malabsorption, see above), the procedure is particularly effective in people whose excess weight is caused by the excessive intake of high calorie food or beverages. For these people, sometimes called "sweet-eaters", a single stomach reducing procedure such as the gastric balloon, gastric banding or sleeve gastrectomy would not be sufficiently effective.
A biliopancreatic diversion is a demanding surgery. Compared to the sleeve gastrectomy, much more cuts and seams are necessary. The intervention in the digestive system is very pronounced and is irreversible even after successful weight loss. It is therefore necessary to understand the possible side effects before the surgery. Their strength differs in each individual case:
Deficiency symptoms: One of the most common side effects of a biliopancreatic diversion is a deficiency of vitamin D and vitamin B12. Vitamin B12 is absorbed in the last section of the small intestine (terminal ileum). However, a certain protein, a so-called intrinsic factor, must be present to aid the absorption. The intrinsic factor is produced in the stomach. Since a large part of the stomach is removed during the biliopancreatic diversion, the formation of the intrinsic factor is reduced and thus the intake of vitamin B12 is also heavily restricted.
Therefore, life-long regular Intravenous or intramuscular administration of vitamin B12 is required. Vitamin B-12 supplements which are absorbed directly by the oral mucosa (sublingual intake) are also available, but their efficacy is questionable.The reason for vitamin D deficiency after a biliopancreatic diversion is not yet clear.
Patients with biliopancreatic diversion must pay careful attention to their level of vitamins B12 and D – otherwise they are threatened by severe complications such as anemia (in vitamin B-12 deficiency) and osteoporosis (due to vitamin D deficiency).
Dumping syndrome: A dumping syndrome is the combination of several symptoms, which are caused by the rapid discharge of largely undigested food from the remaining stomach into the small intestine. Since the pyloric part of the stomach is missing, the concentrated food pulp arrives directly into the small intestine. In the intestine, the food pulp absorbs water from the surrounding tissues and blood vessels following the physical laws (osmosis).
This reduces the amount of fluid in the bloodstream, causing a pronounced blood pressure drop which can result in a collapse. Some people report about related symptoms such as dizziness, nausea, sweating or strong palpitation (early dumping). In addition, high amount of water in the food can cause severe diarrhea.
A dumping syndrome occurs mainly after eating very osmotically active (hyperosmolar) food, for example sugary drinks or fatty foods. The dumping syndrome can be prevented by the PBD-DS (see above). With this variant of the biliopancreatic diversion the pyloric part of the stomach is preserved.
Loss of muscle mass: the greatly reduced supply of nutrients creates a relative deficiency of carbohydrates , which the body compensates by producing sugar from amino acids. Amino acids are the building blocks for proteins, which in turn are an important building material of the musculature. The body thus reduces the little used muscles to secure the energy balance. Patients after a biliopancreatic diversion should therefore counteract muscle degradation by increasing physical activity.
Easy on the joints sports such as bicycle riding, moderate strength training, swimming or aqua jogging are particularly suitable for it.
Various general and specific operational risks are connected with biliopancreatic diversion. These include:
- General Anesthesia Risks
- Thrombosis of deep leg veins with the risk of pulmonary embolism
- Infections in the area of external sutures and wound sutures
- Seam leaks on gastric sleeve/stomach pouch or small intestine (seam insufficiency) with the risk of peritonitis
Studies show that the mortality after the biliopancreatic diversion amounts to 0.5 to 7.6 percent. However, these are purely statistical values. The individual surgical risk depends essentially on the physical state at the time of the operation.
After the biliopancreatic diversion the patient needs to change their basic diet to avoid digestive problems. Apart from that, the weight loss will be more pronounced, if the nutrition after the operation is low in calories and fat. The patient must follow these dietary rules after the biliopancreatic diversion for the entire life:
- Eat in small portions (because of the reduced stomach size)
- Thoroughly chew every single bite, as the stomach does not perform the pre-digestion
- Avoid sugary foods or beverages and meat with long fibers
- Life-long intake of dietary supplements (especially vitamin D, vitamin B12)
Medications are also absorbed differently or with smaller amount of active substances. The biliopancreatic diversion therefore may require an adjustment to the timing and dose of the medications.