Is Loop Duodenal Switch the Future of Bariatric Surgery?

by reeger on January 19, 2018

In this episode, as I promised in my last episode, I bring back Dr Walter Medlin of the Bariatric Medicine Institute in Salt Lake City, Utah to talk about the bariatric surgery known generally as Duodenal Switch, but commonly called the “D.S.” Now for those of you new to the podcast, welcome, I’ve got over 90 past episodes for you to dive into! If you are not familiar with Dr Medlin, he has been a guest on this podcast a few different times. Here. Here. Here. And Here. He is a bariatric surgeon and he is also a bariatric surgery patient, having had Sleeve Gastrectomy, so he brings a unique dual perspective to the conversation.

This episode is both technical, because we have to get into the nitty-gritty of what is actually done to create the DS and, as always, it is conversation style because, well, that’s how we roll. Regarding the technical aspects of this conversation, if you find yourself lost in the verbal descriptions of the GI tract and how it is altered with the DS surgery, then I recommend you go to my website,, to look at the illustrations I have put there because, well, a picture really is worth a thousand words.

But before I cut to the episode, I want to give a shout-out to my new Patrons at These are listeners who have gone above and beyond in their appreciation of the podcast to offer financial backing. Huge shout out to Sandra R., Missy V., Michelle D., Bonnie B., and Marcia T.

If you, dear listener, want to become a supporting member of the podcast for as little as 1$ per month, head on over to and sign on up.

Discussed in this episode:

  • Is there a correct way to pronounce Duodenal? Dew-OH-DE-nahl or Du-WAH-den-nahl? Both are correct.
  • The GI tract from beginning to end. Mouth > Esophagus > Stomach > Pylorus > Duodenum > Jejunum > Ileum > Ileo-Cecal Valve > Ascending Colon > Transverse Colon > Descending Colon > Sigmoid Colon > Rectum > Anus.
  • DS and Roux-en-Y gastric Bypass both “short-circuit” the bowel.
  • DS: The Stomach is “sleeved.” Then the duodenum is divided in half approximately one inch below the Pylorus.
  • The Pylorus regulates the flow of food into the small intestines, which means the risk for Dumping Syndrome is less.
  • The long-term risk for gastric ulcers is much higher in Roux-en-Y Gastric Bypass (RYGB) than in either Sleeve Gastrectomy or Duodenal Switch.
  • The standard, aka “traditional” DS is called Biliopancreatic Duodenal Switch (BPDS) (see drawing below). It bypasses A LOT of small bowel, leaving approximately 1-2 feet of functional small bowel. The result is a higher risk of dehydration, diarrhea, malnutrition, and foul smelling gas. BPDS:
  • The newer Loop DS (see drawing below) bypasses less small intestine, leaving approximately 300cm or 9-10 feet of functioning small bowel. The result is a much lower risk of diarrhea. Loop DS:
  • In order to make the length of the functioning section of the DS, the surgeon begins measuring from the Ileo-Cecal valve.
  • Once the length is measured, the duodenum is divided in half approximately one inch below the pylorus and the Ileum is connected, sewn to, the duodenum just below the pylorus, thus creating a Duodeno-ileostomy. This creates the “Loop” part of the DS.
  • Before the Duodeno-ilestomy is created, the surgeon performs the sleeve gastrectomy.
  • The remaining Duodenum is not removed. Bile and Pancreatic enzymes still enter the Duodenum and flow down the duodenum, past the Duodeno-ileostomy and into the “common channel.”
  • One of the risks to a Loop DS is that bile and pancreatic enzymes can reflux up into the sleeve stomach but in order for this to happen, the enzymes would need to pass through the pylorus, which is possible but does not happen often because the pylorus is a very strong tubular muscle that is pushing stomach contents downstream.
  • Loop Duodenal Switch can also be correctly called Single Anastomosis Duodeno-ileostomy with Sleeve (SADI-S) or Stomach Intestinal Pylorus-Sparing Surgery (SIPS).
  • The “Classic” duodenal switch, BPDS, involves two anastomoses. Some would consider this a more complicated surgery to perform, with higher risks.
  • Why might a bariatric surgeon choose to NOT perform DS? The anatomy around the duodenum is complicated with higher risk for injury to surrounding tissue.
  • The benefits to the Loop DS is better weight loss, less risk of gastric ulcers, and less risk of internal hernia compared to Gastric Bypass.
  • Sometimes DS is a “staged” surgery, meaning the first operation is the Sleeve Gastrectomy and then months later the surgeon performs the duodeno-ileostomy part of the surgery.
  • The risks of Loop DS are few but do include diarrhea, gastric reflux, foul smelling gas (farts), vitamin deficiencies (especially fat soluble vitamins, A,D,E,K) if not taking vitamins regularly

Connecting with Dr Medlin
Twitter: @bonuslife
Bariatric Practice: Bariatric Medicine Institute

Connecting with Reeger

I believe in you


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