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What is a Single Anastomosis Duodenal Switch

The Single Anastomosis Duodenal Switch is a weight-loss surgery which involves the permanent removal of the left part of the stomach. In the same procedure, about half of the upper small intestine is bypassed which causes a reasonable decrease in the absorption of calories in the body.

This procedure is also known as; the Stomach Intestinal Pylorus Sparing Surgery (SIPS), the Single Anastomosis Duodeno Ileal Bypass with Sleeve Gastrectomy (SADI-S).

The Need for the Single Anastomosis Duodenal Switch

Obesity and excess weight is a major health concern in Lebanon. Studies show that obese and overweight people are much more likely to develop serious health conditions including; heart disease, Type 2 diabetes, high blood pressure, some cancers, fertility problems, stroke and sleep apnea just to name a few.

While excess weight is a known factor in these serious health conditions, studies show that people with overweight are up to twice at risk compared to other people.

This procedure has proved to be very effective not only in aiding weight loss but more importantly in sustaining long-term weight loss maintenance.

To watch a live surgery of this procedure, (Single anastomosis duodeno-ileal bypass with sleeve gastrectomy SADI-S), please follow the link

Basic Concept behind the Single Anastomosis Duodenal Switch
Anastomosis refers to a ‘surgical connection’. A single-anastomosis duodenal switch in its simplicity therefore means that in this procedure, only one anastomosis, or surgical connection is needed. This procedure can be said to be a simpler, safer, and much more effective form of the original Duodenum switch which involved surgical connections on two points. While the duodenal switch proved to be one of the best tools in current weight loss surgery, it was also associated with a significant number of complications. Many surgeons declined to perform the procedure because the surgery was considered difficult, posing many pre and post-operative problems.

The SADI-S was therefore developed as a new form of Duodenal Switch. Because the improved procedure involves just a single-anastomosis (surgical connection), it is considered to be safer, much simpler to perform and just as effective as the standard Duodenal Switch.

How is it Different from The Standard Duodenal Switch?
Where the standard Duodenal Switch involves cutting across two points of the small intestine, this procedure transection is only done on one (single) point. Since the Standard Duodenum Switch has only one surgical connection, the operative time and complications (like leakage and obstruction) are significantly reduced. In addition to this, unlike the standard Duodenal Switch, the bowel is not divided hence no mesentery defects (spaces on the supporting tissues) are created. These mesentery defects have been known to cause bowel obstruction in Duodenal Switch, commonly referred to as internal hernias.
Benefits of the Single Anastomosis Duodenal Switch
  • Over 70% long-term weight loss reported.
  • Improvement in all serious health complications associated with excess weight and obesity including: Type-2 diabetes, Hypertension, sleep apnea, depression and high cholesterol among others.
  • Reduced risk of ‘dumping’ syndrome as a result of the pylorus preservation. Because of the malabsorption, sustained weight-loss can be predicted.
  • Fewer malabsorptive symptoms compared to those experienced in a standard Duodenal Switch have been reported. This is because the common channel in a SADI-S is almost twice longer than that of a traditional Duodenal Switch.
How Does It Work?
Dr Safa will permanently remove most of the elastic outer and upper part of the stomach. Up to 70% of the stomach is removed reducing the capacity of the stomach from 1000 ml to 120 ml (a quart to 3 or 4 oz.). After the operation, only a small tube-like stomach remains (commonly referred as sleeve). Patients can only eat as much solid food as the size of the remaining stomachs. If the stomach is reduced to 4 oz., the patient will usually feel full after eating only 4 oz. of food.

This procedure does not alter stomach functions. The antrum (the pump responsible for pushing food through the valve at the end of the stomach), the nerves that control the functions of the stomach and the pylorus are left intact. Although the stomach capacity is reduced, the remaining stomach functions exactly the same way a normal stomach should. After getting this procedure done, a patient will be able to eat and enjoy a comparatively normal diet as before although in much smaller quantities.

The intestines are rerouted such that almost half of the smaller intestine is bypassed in order to reduce the amount and rate at which calories are absorbed. The upper section of the small intestine (duodenum) is cut across after the pylorus. Dr Safa then re-attaches the small intestine (located around 250-300 cm from the colon) to the duodenal stump, located just past the pyloric valve.

This usually creates a loop or ring which diverts food flow from the upper half of the duodenum. The upper part of the intestine will now carry digestive juices (bile and pancreatic juices). This upper part is referred to as the biliopancreatic limb (BPL). Consumed food mixes with the digestive juices in the last part of intestine also known as the Common channel (CC). The rate at which nutrients and calories will be absorbed will depend on the length of the common channel. A shorter common channel reduces calorie absorption and consequently the chance of weight re-gain.

Another reason why SADI-S has proven very effective in long term weight reduction and consequent diabetic resolution is perhaps because of the significant reduction of Ghrelin, an appetite-producing hormone, that affect the metabolism in a negative way. The tissue that produces ghrelin is usually located in the fundus (the outer- upper part of the stomach).

Since this portion of the stomach is permanently removed, most patients who have undergone this procedure reported a significant decrease in appetite. In addition to this, food reaches the lower intestines faster than usual because the intestines have been bypassed. As a result, appetite repressing hormones like polypeptide YY (PPY) and glucagon-like peptide 1(GLP1) are released.

Critics of the Single Anastomosis Duodenal Switch
Although the ‘loop anatomy’ was largely rejected by pioneering bariatric surgeons, the SADI-S has increasingly become popular in most countries in the last decade especially since the reintroduction of the ‘mini’ gastric bypass. This concept has convinced many surgeons around the world of the importance of this technique. Recently, many critics argue against the necessity of the ‘Roux anatomy’ in a successful bariatric operation. They believe that the ‘Roux anatomy’ introduces more risk to the procedure compared to the loop configuration.
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