SADi-S or BPD/DS: Comparing Types of Duodenal Switch Surgery

Duodenal Switch Surgery and its variation are by far the most advanced and effective bariatric operations. It combines restriction (gastric sleeve) and malabsorption (RNY gastric bypass) aspects to promote significant weight loss and resolve comorbidities. There are two kinds of duodenal switch procedures.

  1. Biliopancreatic diversion with duodenal switch (BPD/DS) removes 70% of the stomach entirely and reroutes the intestines to bypass most of the small intestines.
  2. Single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) is similar to the standard BPD/DS with one fewer connection to the intestine.

The classical DS-BPD is a technically more challenging operation. SADI is a less complex surgery producing almost the same weight loss and metabolic results.

You will learn about physiological differences between traditional BPD-DS and SADi-S and compare outcomes such as weight loss, T2DM, and nutritional deficiencies.

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About Duodenal Switch Surgery (BPD/DS)

Duodenal Switch Surgery Schematic - How it Works - DS in Mexico

The Biliopancreatic Diversion (BPD), an earlier version of Duodenal Switch, was a surgery similar to a gastric bypass. 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.

The fact that pancreatic juices and bile were only introduced into the intestines very late in digestion resulted in malnutrition. After experiencing the long-term problems caused by the BPD, the procedure was modified to the Duodenal Switch-Biliopancreatic Diversion (DS-BPD) in 1988.

How BPD/DS Works

  • Part 1 – Remove 70% of the greater stomach curvature, shaped like a gastric sleeve.
  • Part 2 – The intestinal bypass portion of the surgery is performed (after some time in higher BMI patients) – creating a 100 cm common channel with a 200 cm alimentary limb.

After seeing the results and the subsequent weight loss from the first part, some patients opted not to continue with the second part. That is how Gastric Sleeve, so-called Vertical Sleeve Gastrectomy (VSG), became popular as a stand-alone treatment option in weight loss and obesity management.

Performing the surgery can take many hours, which greatly increases the chance of complications; it was split up into a step-wise procedure.

Check out our Duodenal Switch Before and After Photos

About Single Loop Duodenal Switch Surgery (SADi-S)

SADi - Single Loop Duodenal Switch

Single Anastomosis Duodeno-Ilean bypass with Sleeve Gastrectomy (SADI-S), also known as a single-loop duodenal switch or Stomach Intestinal Pylorus Sparing (SIPS), is a variation of classical duodenal switch. The single-loop duodenal switch (SADi-S)  aims to reduce this risk by having only one anastomosis.

How Does SADi-S Work?

In Loop DS, the common channel (where nutrients are absorbed) and alimentary limb are the same tracts – typically 250 to 300 centimeters (8.2 ft) long.

Every anastomosis (or intestine connection) significantly increases the risk of leaking and spilling potentially harmful matter into the peritoneum. 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, the gallbladder is usually removed during the surgery. Patients who lose a large amount of weight after bariatric surgery may need gallbladder removal at a future date to avoid gallstones.

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

Type of Surgery

Duodenal Switch

Duodenal Switch Digestive Tract


SADI-S Digestive Tract - Single Loop Duodenal Switch

What It Does

Restrictive and MalabsorptiveRestrictive and Malabsorptive


– Reduces stomach size
– Double anastomosis for malabsorption
– Reduces stomach size
– Single anastomosis for malabsorption


Reduces the nutrients and calories absorbedReduce the risk with single anastomosis
Advantages– 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
– Low degree of GI Side-effects


– Some foods may not be digested well
– Cause discomfort
– Dumping syndrome if one eats poorly
– Stomach can be stretched
– Patients need vitamins for the rest of their lives
– Must take all essential nutrients that are not absorbed
Complications– Stomach or abdominal pain
– Acid reflux
– Lack of important nutrients
– Nutrient and vitamin deficiency
– A newer procedure with less data


– Very complex surgery
– Risk of a leak
– High Malnutrition
– Complex surgery
– Risk of a leak
– Malnutrition


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

– 89% remission of type II diabetes
– T2DM on insulin: 75%
– 72% remission of 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. Still, 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, 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 would be the intestinal connection. It has 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 than typical gastric bypass surgery. The risk of protein malnutrition is still present in the 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 an 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 bile to avoid getting into the stomach, avoiding stomach discomfort and irritation.

In traditional DS, the alimentary limb and common channel are separate, wherein SADI-s, are not separated. This results in selective fat malabsorption and selective nutrient absorption in classical DS not present in SADI-s. There is a higher caloric absorption in SADI-s compared to BPD-DS.

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


Surgery Outcomes

Evidence has been 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 improving glucose control in diabetes compared to a DS or SADI-S operation.

While the long-term evidence suggests that the actual weight loss is not better or worse in the DS/SADI-S option compared to gastric bypass surgery, other benefits of SADI-S and DS do not occur in gastric bypass, which also contributes to weight loss and weight control.

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

Not sure which is the best option for you? Fill out a free Health Questionnaire to get a recommendation from a qualified bariatric surgeon


Many studies show that BPD/DS and SADI-S are both surgeries with positive outcomes for morbidly obese patients. They proved themselves efficient for achieving significant, sustained bodyweight reduction and curing medical conditions related to obesity, such as diabetes.

The decision of which surgery to perform lies in the surgeon’s hands of what they consider best for you.

While the evidence is clear that both options have the desired outcomes, no long-term comparative data is dictating which option is actually the best. SADI-S is more suitable for smaller patients with nutritional or GI concerns. It is also a less dangerous operation with more infrequent complications.

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