Single-Loop Duodenal Switch (SADi-S) vs Duodenal Switch (DS)2018-10-12T22:42:37+00:00

Single-Loop Duodenal Switch (SADi-S) vs Duodenal Switch (DS)

Most doctors and people, in general, have never even heard of a Duodenal Switch (DS). The duodenal switch surgery happens to be one of the most efficacious and powerful tools currently available to battle the issue of obesity and aiding in weight loss.

The Single Loop Duodenal Switch surgery (loop DS or sadi-s) is a powerful procedure using only one connection to the intestine, instead of two like the standard duodenal switch surgery.

You will be learning about physiological differences between DS and SADI-S/SIPS as well as a comparison of outcomes, such as weight loss, T2DM, and nutritional deficiencies.

What is Loop Duodenal Switch?Loop Duodenal Switch

Weight loss surgery has been around for quite some time, with newer and better surgeries being invented. The duodenal switch was one of these surgeries found to increase the outcomes of weight loss among the patients it was performed on. However, it was also found that many surgeons do not perform it because of the level of difficulty associated with the surgery and the greater risks involved.

In order to negate these downsides of the duodenal switch surgery, a better, faster, and safer technique was invented, called the Loop Duodenal Switch, Single Anastomosis Duodeno-Ilean bypass with Sleeve Gastrectomy (SADI-S), or Stomach Intestinal Pylorus Sparing (SIPS).

The Single Anastomosis Duodeno-Ileal bypass with Sleeve Gastrectomy (SADi-S), also known as a single-loop duodenal switch, is the newest variation of this type of weight loss surgery. The word “anastomosis” means a “surgical connection”, for example, cutting one end of the small intestine and attaching it to the surface of the skin to form a temporary stoma. When pieces of intestine and a piece of the stomach are brought together to form a continuous tube.

Biliopancreatic Diversion (BPD)

Before the Duodenal Switch was the Biliopancreatic Diversion (BPD), and the DS is actually a variation of the original surgery. The DS is sometimes referred to as the Duodenal Switch-Biliopancreatic Diversion (DS-BPS), but it is the same thing.

The BPD was a surgery similar to a gastric bypass, but the only differences were a much longer Y-shaped intestine and a bigger stomach pouch. The biggest part of the intestines was bypassed, and only the most distal piece was reattached to the stomach. Essentially, this resulted in malnutrition due to the fact that pancreatic juices and bile were only introduced into the intestines very late in the digestion process.

Normal Duodenal Switch Surgery (DS)

Duodenal Switch

In order to understand how the single loop duodenal switch works, you should understand how the normal duodenal switch surgery (DS) works. After seeing the long-term problems caused by the BPD, it was modified to the DS-BPD in 1988. Instead of cutting the stomach into halves, it was rather made into a Sleeve Gastrectomy shape. The ileum is attached below the pylorus.

It was essentially the same as the BPD, but there was a longer portion of intestine for the mixing of the pancreatic juice and bile in order to improve malnutrition. Performing the surgery can take a great many numbers of hours, which greatly increases the chance of complications, it was split up into a step-wise procedure.

Part 1 is the Sleeve Gastrectomy or Gastric Sleeve Surgery, after which the patient was allowed to recover from the operation.

After some time, Part 2 or the intestinal bypass, portion of the surgery is performed.

After having the Sleeve Gastrectomy or Gastric Sleeve surgery and already being satisfied with the results and the subsequent weight loss, some patients opted not even to continue with the second part. It was because of that the Gastric Sleeve became the popular stand-alone treatment option in weight loss and obesity management.

How Single Loop Duodenal Switch Surgery Works

The single-anastomosis duodenal switch or loop duodenal switch was created to reduce risks and complications of the standard duodenal switch surgery. Because cutting the intestines and sewing it to other organs is always a cause for concern due to the risk of spilling intestinal contents into the peritoneum, the purpose or goal of the single-loop duodenal switch (SADI-S) was to reduce this risk by having only one anastomosis.

The risk of leaking and spilling potentially harmful matter into the peritoneum is significantly increased with every anastomosis (or intestine connection). Additionally, fewer connections directly translate into a possibly shorter surgery, making it easier to perform in one step and reducing intra-operative risks such as hemorrhage and infection.

In the Single Anastomosis Duodenal Switch, or SADi’s, the gallbladder is usually removed during the surgery. Generally, the surgeon removes the gallbladder during the BPD/DS surgery. Rapid weight loss increases the risk of gallstones. Patients that lose a large amount of weight after bariatric surgery may need gallbladder removal at a future date.This makes removing the gallbladder an important part of the duodenal switch surgery.

The full bariatric procedure name for the loop ds is Single Anastomosis Duodeno-Ileal Bypass with Sleeve Gastrectomy (SADi-S).

Comparison Between Duodenal Switch and Single-Loop Duodenal Switch (SADi-S)

Type of Surgery

Duodenal Switch (DS)

Duodenal Switch Digestive Tract

Single Anastomosis Duodenal Switch (SADi-S)

SADI-S Digestive Tract - Single Loop Duodenal Switch

What It Does

Restrictive and MalabsorptiveRestrictive and Malabsorptive


Reduces stomach size by approximately 80% as the restrictive component. Variation of biliopancreatic diversion or BPD. The duodenal switch leaves the pyloric valve to regulate the byproduct of the stomach in the small intestine. Malabsorptive part restricts the number of nutrients absorbed by the stomach and small intestine.Newest variation of weight loss surgery that reduces and decreases the greater curvature of the stomach which decreases the intestines size so fewer nutrients are absorbed. Known as “Single-Loop Duodenal Switch. SADi-s cutting one side of the small intestine and connecting the intestine to create a stoma. Attaching the stomach and the intestines into a continuous tube.


Reduces the number of nutrients and calories by bypassing a significant amount of the small intestines, up to 75-80%.Reduce risk of the Duodenal Switch Surgery by only having a single anastomosis, creating the name “Single Anastomosis Duodeno-Ileal Bypass with Sleeve Gastrectomy, or SADi-S.


  • Less hungry and less urge to eat
  • Body absorbs fewer nutrients or calories
  • Lose most weight in the first year
  • Long-term weight loss
  • Improvement of glucose control
  • One fewer anastomosis or mesenteric window
  • Low complication rate
  • Lower degree of GI Side-effects


  • Some foods may not digest well or cause discomfort
  • Patients can have dumping syndrome if eat poorly
  • Stomach can be stretched
  • Patients need Vitamins throughout their lifetime
  • Must make sure you have all the essential nutrients that are not absorbed through food


  • Stomach or abdominal pain
  • Acid reflux
  • Lack of important nutrients
  • Nutrient and essential vitamin deficiency
  • New bariatric procedure, meaning not as much testing as other weight loss surgeries


Rearrange a large portion of the small intestine which withholds a lot of key nutrients and vitamins from absorbing into your body.Leaking or spilling harmful matter increases with every additional anastomosis performed or loop.


2 to 4 days2 to 3 days

Time Off Work

2 to 3 weeks recommended1.5 to 2.5 weeks

Complete Recovery

5 to 6 weeks4 to 6 weeks


45% at 2 years35% at 2 years


  • Protein malnutrition 14% at 2 years
  • Albumin mean (SD) 40.7
  • Vitamin A 27.2% abnormal
  • PTH 33% abnormal
  • Vitamin D 55% abnormal
  • Protein malnutrition 10% at 2 years
  • Albumin mean (SD) 39
  • Vitamin A 53% abnormal
  • PTH 54% abnormal
  • Vitamin D 46% abnormal

Metabolic Outcome

  • T2DM remission: Over 89% success in curing Type II Diabetes
  • T2DM on insulin: 75%
  • T2DM remission: Over 72% success in curing Type II Diabetes
  • T2DM on insulin: 50%

Health Benefits

  • Sleep Apnea
  • Resolves irritable bowel syndrome

Similarities Between DS and SADI-S:

Both surgeries are performed using the laparoscopic technique, but on some rarer occasions, some patients may require a laparotomy (cutting the abdomen wide open) for reasons that are usually determined pre-operatively. Both operations can be performed in two stages, which is potentially advantageous to patients at high risk for developing complications.

For both the DS and SADI-S the first part would be the Sleeve Gastrectomy and the second part would be the intestinal connection. It has actually been shown to be safer to perform the second stage of the surgery once the patient has lost some weight. These options are both less complicated that typical Gastric Bypass surgery. The risk of protein malnutrition is still present in loop duodenal switch.

Differences Between DS and SADI-S

The Duodenal Switch procedure has been around for quite some time, and when it was typically performed, it was done as in open procedure rather than a laparoscopic one. This has led to a lack of evidence supporting positive outcomes if the DS surgery is to be performed laparoscopically. Also, the Y-shape connection in the Duodenal Switch surgery allows an avoidance of bile from getting into the stomach, resulting in the avoidance of stomach discomfort and irritation.

The Loop Duodenal Switch, also known as SADI-S or SIPS, on the other hand, has a reduced operative time which leads to the reduction in the risk of complications related to prolonged surgery, purely due to the fact that there are fewer anastomotic connections that need to be made. The risk of leaking or blockage is also reduced. Since the bowel is not being divided into 2 segments, there is less chance to develop intestinal entrapment in the dead spaced between segments of the mesentery.

Surgery Outcomes

There has been evidence published that having a Duodenal Switch is a better option for weight loss surgery in candidates with a BMI of over 50. The gastric bypass has also been found to be an inferior option in the improvement of glucose control in diabetes which compared to either a DS or SADI-S operation.

While the long-term evidence suggesting that the actual weight loss has not been found to be better or worse in the DS/SADI-S option compared to gastric bypass surgery, there are other benefits of SADI-S and DS that does not occur in gastric bypass which also contributes to weight loss and weight control.

There is also a reduction in cholesterol due to the inability for it to be absorbed in both surgeries. This does, however, cause one of the most common side effects of the surgery which is malabsorption of fats. The result is abdominal cramps, frequent stools which are difficult to flush, and flatulence which is particularly foul-smelling. This is not the only malabsorption that occurs in patients who have had the DS/SADI-S surgery.

They are also prone to becoming vitamin deficient, specifically for vitamins D, E, A and K since these are all fat-soluble. It is important to remember to be supplemented with these vitamins.


The DS and the SADI-S are both surgeries which have shown positive outcomes in many studies, proved themselves as an efficient way for achieving significant body weight reduction and reduction of problems and medical concerns related to obesity such as diabetes.

In general, SADI-S is more suitable for smaller patients with nutritional or GI concerns. While the evidence is clear that both options have the desired outcomes, there is no long-term comparative data dictating which option is actually the best. Therefore, the decision of the surgery lies in the hands of the surgeon and what they are comfortable performing.