Duodenal Switch

A duodenal switch is the name given to an obesity surgery procedure. It is comprised of two elements – restrictive and malabsorptive. These two aspects mean that the food intake is reduced and fat absorption is dramatically affected. Basically, the patient can only eat small amounts of food; plus the absorbed food is not broken down as normal which means fat is not absorbed into the bloodstream. These smaller portions combined with limited fat absorption result in reduced calories and weight loss.

Patients are looking at only 20% fat absorption. The risk here is that essential vitamins and minerals are not absorbed which can lead to deficiencies. As a result of this patients are advised to take a daily multivitamin/mineral supplement.

What is a duodenal switch?

This is also known as a Biliopancreatic Diversion with Duodenal Switch (BPD/DS): it is a surgical procedure in which the stomach is reduced in size and the small intestine is rearranged so that food travels down a separate part of the intestine from bile and pancreatic juices or enzymes. In effect there are three channels: the first one or ‘digestive’ channel is where food travels from the stomach into the small intestine. The second or the ‘biliopancreatic’ channel is responsible for the passage of bile from the liver and pancreatic juices. The third channel is the junction at the end of both of these. This channel is where food and these juices mix before entering the large intestine. This is where food is broken down but the body has limited time in which to do so. This means that less fat and calories are absorbed.

In fact, only 20% fat is absorbed as a result of this procedure.

The procedure

The procedure involves the surgeon removing a large portion of the stomach. This is done as a ‘sleeve gastrectomy’: the surgeon will remove up to 85% of the stomach and reshape the remaining section so that it forms a tube or banana shape.

He/she will also ensure that the pyloric valve – the opening from the stomach which controls the flow of food into the small intestine - is left intact.

This is the restrictive half of the procedure.

The surgeon will then take the small intestine and reroute this so that one end is attached to the pyloric valve and the other into the large intestine. This forms a shorter channel called the ‘digestive’ channel.

He/she will take another section of this small intestine which forms the longer channel or ‘biliopancreatic loop’. This channel is where bile and pancreatic juices travel through. These travel down this channel until the reach the start of the large intestine. The bottom of this channel joins the bottom of the digestive loop. This third channel or junction is where the bile, pancreatic juices and food mix together. This reduces the amount of time that the body has in which to break down this food. This process means that fewer calories are absorbed into the bloodstream, and most importantly, less fat. Smaller portions and fewer calories mean that weight will be lost. This is the malabsorptive half.

Note: the gallbladder may also be removed to prevent the risk of gallstones which can occur after rapid weight loss.

The downside here is the risk of vitamin/mineral deficiencies. The normal breakdown of food means that essential vitamins and minerals are absorbed and utilised by the body. But if this process if affected then the patient will have to take a daily vitamin supplement for the rest of their life.

Advantages of duodenal switch

This procedure means that large amounts of weight will be lost – mainly due to the restricted amounts of food that can be ingested as well as the limited fat absorption. Also, the pyloric valve is kept in place which means no ‘dumping syndrome’ as experienced by patients who have had Roux-en-Y gastric bypass. The pyloric valve controls the passage of food from the stomach into the start of the small intestine. Removal of this can result in large amounts of food being emptied or ‘dumped’ rapidly into the small intestine. This is a very unpleasant condition which can cause symptoms of nausea, bloating, cramping, dizziness and vomiting.

The duodenal switch prevents this from happening along with the risk of ulcers, stoma closures and blockages. Another advantage is that the removal of a large portion of the stomach also removes the production of ghrelin. Ghrelin is a ‘hunger hormone’ which is produced in the stomach before travelling through the bloodstream to the brain. Once there it triggers feelings of hunger. Removing the site of this production means that the patient will experience very little feelings of hunger.

Diet is not affected in the same way as patients who have had gastric bypass surgery. The patient will have to follow a healthy diet and eat smaller portions but it will be a more ‘normal’ diet than that of other procedures. Finally, the small intestine is rerouted NOT removed; this means that this half of the procedure is fully reversible.

Disadvantages of duodenal switch

All surgery carries a small amount of risk and duodenal switch is no different. The main disadvantage is that the patient has to take a daily multivitamin/mineral supplement to prevent any deficiencies.

This will take the form of vitamins A, D, E and K plus a calcium supplement. The patient may also have to take iron and potassium supplements.

Failure to do so can result in osteoporosis, night blindness and anaemia. The patient will require regular check ups as well a blood tests to ensure that this and other conditions do not occur. This procedure results in rapid weight loss which can cause the formation of gallstones. However, the surgeon may remove the gallbladder during this procedure or prescribe medication following surgery to prevent this. The remaining stomach pouch will stretch over time.

And, there are the risks usually associated with any form of surgery which include infection, leakage, blood clots, blood loss and perforation of the stomach or the bowel. Death only occurs in around 0.5% of cases.