The Duodenal Switch

The Duodenal switch is the most recent version of the bilio-pancreatic diversion.  It is a complicated surgery, and in 2004 only about 40 surgeons in the United States are performing this surgery.  This surgery is highly effective in keeping weight off patients, so some surgeons use this surgery for their patients who are considered super morbidly obese.   However, some surgeons use this as their sole weight loss surgery option for patients, feeling that this is the most effective and long lasting of all weight loss surgeries. In addition to restricting the amount of food a person can eat, this surgery also has a “malabsorptive” component.

The Stomach

In Duodenal switch surgery, about 80 to 90 percent of the stomach is removed. stomach is gone, not left in your body— but gone. Instead of your stomach looking like a canvass wine jug, it looks more like a long tube. The normal stomach can hold about 50 ounces, or 1.5 liters. After the Duodenal switch surgery, your stomach can hold about 4 to 8 ounces, or 0.12 to 0.24 liters. This enforces portion control. Over time your stomach will enlarge a bit to accommodate a small to medium sized meal (not a super-sized meal).

With the Duodenal Switch the Pylorus remains functional

In the Roux en Y Gastric Bypass surgery, the stomach pouch holds one ounce, but the stoma is always open, so patients who have this gastric bypass can drink a lot of fluids.  One of the keys to successful weight loss after the Duodenal Switch is a muscle called the pylorus at the end of the stomach.  The pylorus is technically a muscular sphincter or a valve.  It stays shut while food and fluid are in the stomach, allowing the stomach to work as a hopper and digest food.  When the food is ready to go into the small bowel, it opens and the partially digested food goes into the duodenum.  Fluids empty much faster than solids.  Because of the pylorus, food stays in the stomach until it is ready to hit the intestine—technically speaking, the digestion allows the food to become iso-osmolar.  Osmolality is a measure of the total number of particles in a solution.  In this case fluids are mixed with particles of solid food.  Keeping food in the stomach until it is digested prevents dumping—as in eat it now, take a dump (bowel movement) immediately after.  Some consider dumping to be a key component of gastric bypass.  However, there is no relation between dumping and weight loss, and dumping is NOT fun.

Patients cannot drink a lot because the stomach fills and they have to wait for the pylorus to open and allow the fluid to flow out. Early in the postoperative period, if patients start to vomit, the area around pylorus swells and can keep the pylorus from opening—these patients may need to spend some time in the hospital getting intravenous fluids and not eating or drinking. The pylorus is key to weight loss because, unlike the gastric bypass, patients with the DS can eat and drink at the same time. Remember, with the gastric bypass, eating and drinking at the same time food can push food through the stoma into the intestine, and you will continue to feel hungry. With the DS surgery, you will simply fill up faster if you eat and drink at the same time. This helps you to control weight later on as the stomach stretches a bit because, in addition to eating some protein, you can fill up by drinking a bit of water.

More facts about the stomach and Duodenal Switch Surgery

Most of the acid-secreting portion of the stomach is removed—but the bit that is left can still cause an ulcer. Some patients will require lifelong therapy with acid suppressing drugs (Prevacid®, Pepcid®, etc.).

The advantage of this surgery is that if you develop an ulcer, your stomach can be completely examined with a scope, and sometimes the ulcer can be easily treated without surgery. Patients who have a duodenal switch can have aspirin, Motrin®, Naprosyn®, Viox®, and other non-steroidal anti-inflammatory medicines.

With gastric bypass surgery there is always concern that pills can be caught in the stoma.  This is not a concern with the DS, so you can continue to take pills, no matter what size.

You can eat fruits and vegetables with the Duodenal Switch

Bezoars are very uncommon with the duodenal switch so you can eat fibrous fruits and vegetables that make up a healthy diet.  Sometimes, a year or two following surgery, your the stomach stretches and you may find you are still hungry even after you have had your protein.  A healthy advantage to the DS is that you can add vegetables to your diet to help fill you up.

Duodenal Switch weight loss surgery

Duodenal Switch...step-by-step

Some surgeons advocate doing this surgery in two parts.  In the first operation, part of the stomach is removed (partial gastrectomy).  This can be done fairly safely and through a laparoscope.  This restrictive component allows patients to lose a fair bit of weight, and come back later for “the switch,” portion of the operation.  Patients who are candidates for this include those who have very high BMI’s, have many medical problems, and those who are on medicines that might be malabsorbed from the switch.  In addition some patient’s anatomy is such that they cannot safely have the bowel brought up for an anastomosis to the duodenum.  Some patients never need to have the second portion of this surgery done as they lose enough weight with the restrictive portion alone.

The Switch

A Roux limb is constructed, but instead of draining the contents of the stomach into the intestines, it goes to the first portion of the duodenum.  Since the average length of the small bowel is around 650 cm, this means that 450 cm of small bowel is not seeing food.  The 450 cm of small bowel (give or take a few centimeters) is called the bilio-pancreatic limb.  The bilio-pancreatic limb isn’t empty, but contains digestive enzymes, bile, and a few other things.

The last 100 cm is where most digestion takes place. Some surgeons vary the size of this common channel. Some make this about 75 cm, some make it 125 cm.  In the early days of the operation, many surgeons made this common channel 75 cm, but that did not provide some patients with enough surface to adequately absorb protein.  These patients had to be taken back to surgery to have this revised to a longer limb.

Patients who are quite obese might have a shorter common channel. There is no way of knowing if the limb is too long or too short, but most surgeons are comfortable with 100 cm.

The surgery can be done through a laparoscope, or an open or a hand-assisted approach may be used. Hand-assisted laparoscopy is a combination approach, mostly laparoscopic, that allows the surgeon to reach inside the abdomen through a three-inch incision while also using a laparoscope.

Advantages of the Duodenal Switch

• Ability to use endoscopy to see the entire stomach

• No dumping

• Ability to take non-steroidal anti-inflammatory drugs (aspirin, Motrin, etc)

• Ability to eat fibrous fruits and vegetables

Controversies with the Duodenal Switch

Insurance companies may deny a patient payment for the duodenal switch in the mistaken belief that the malabsorptive portion of the DS is similar to the jejunal-ileal bypass.  With the JI bypass, there were a number of long-term effects: the most severe was liver failure from cirrhosis.  The DS procedure has been practiced since an article about it was first published in 1987, and it has been used for bariatric surgery since 1988.  No long-term malabsorptive problems have been encountered with this surgery.

The forerunner to this surgery was Dr. Scopinaro’s Bilio-pancreatic diversion. He published his follow up of patients showing that his BPD was the most effective treatment of obesity.  Dr. Hess, in Ohio, first combined the duodenal switch with the BPD, and his long-term results have also been published.  Ultimately, reports have shown that DS combined with BPD produces a more stable weight loss with fewer problems than BPD alone.

Unfortunately, in spite of clinical data that shows superiority of the DS over other procedures, it is still classified "experimental" by some insurance companies.  None of the problems with the Jejunal-ileal bypass have ever been encountered with either the BPD or the DS/BPD.  In fact, many of the problems encountered with the RNY, such as dumping, are avoided with the DS.  The long-term data available for the DS is better than the data for RNY.

Disadvantages of the DS

• Patients tend to have loose stools – 3 a day average

• Excessive carbohydrates or fats lead to gas

• Need for eating adequate protein to prevent deficiency

Because there is less small bowel available for digestion there is an increased protein requirement.  Occasionally patients will need prescriptions for pancreatic enzyme supplements to be able to absorb more of the protein they are eating.  This is done as an alternative to increasing the length of the common channel.