Single-Anastomosis Duodenal Switch(also known as SIPS)



A cutting-edge surgical procedure for weight loss.



The single-anastomosis duodenal switch, also called stomach intestinal pylorus sparing surgery (SIPS), or the single loop DS, is very similar to the standard duodenal switch operation, except that the small intestine is only transected at one point instead of two. With this operation, the majority of the most stretchable portion of the stomach is permanently removed (as in a sleeve gastrectomy) but basic stomach function remains the same. In addition, roughly half of the upper small intestine is bypassed, resulting in a moderate decrease in calorie absorption. Weight loss is achieved both through restriction of food consumption and malabsorption, which results in very good long-term weight loss maintenance.







How It Works

With this operation, the surgeon permanently removes the stretchy outer and upper 85 percent of the stomach, leaving a small, tube-shaped stomach. Stomach capacity is reduced from about a quart (1,000 ml) to roughly 3-4 ounces (120 ml). Depending on the size of the tube that is created, patients generally report feeling full after eating 3-4 ounces of solid food.








The important functional elements of the stomach are preserved, including the antrum (the pump that pushes food through the valve at the bottom of the stomach), the pylorus, and the nerves that control stomach function. The result is a much smaller stomach that functions very similar to a normal stomach. Patients are able to enjoy a relatively normal diet and feel satisfied (in much smaller quantities), without experiencing “dumping” syndrome.








In addition, the surgeon will re-route the intestines so that calorie absorption is moderately reduced. The duodenum (the first section of the small intestine) is transected after the pylorus. Rather than transecting the lower intestines (as is done with the standard duodenal switch), the surgeon simply attaches the small intestine at point approximately 8-10 feet or 250-300 cm from the colon to the duodenal stump just beyond the pyloric valve. This creates a loop that diverts the food stream from the top half of the small intestines. The top half of the intestine now carries just digestive juices (bile and pancreatic juices) is called the bilio-pancreatic limb (BPL). The last segment of the intestine where the food and digestive juices mix is referred to as the common channel (CC). Absorption of nutrients and calories is determined by the length of the common channel, so a shorter channel helps decrease the chance of weight regain by decreasing calorie absorption.









One reason that good long-term weight loss has been reported with the duodenal switch with single anastomosis is likely due to a dramatic decrease in the apetite-producing hormone known as ghrelin. The tissue that produces the hormone is almost completely removed with the stretchy outer portion of the stomach. Patients typically report a significant decrease in hunger and food consumption after this operation. In addition, re-routing the intestines helps bring food to the lowest portion of the small intestines earlier than usual which releases important appetite-suppressing hormones such as polypeptideYY (PYY) and glucagon-like peptide 1 (GLP1). This may explain the superior weight loss, weight maintenance and diabetes resolution associated with this surgery.









  • Approximately 70% excess weight loss (EWL) has been reported. (7) (Excess weight is the amount of weight over what is considered the “ideal body weight” for a person’s height [Current Weight – Ideal Weight = Excess Weight]. The percentage of excess weight loss (%EWL) is the percentage of weight loss from this excess weight.)
  • Improvement/resolution in all major co-morbidities, including type 2 diabetes, sleep apnea, hypertension, high cholesterol and depression. (8)
  • There is very little risk of “dumping” syndrome—which occurs when a patient consumes sugar or carbohydrates, or eats too quickly, causing nausea, cramping, diarrhea, sweating, vomiting and heart palpitations.  Preservation of the pyloric valve provides for a more physiologic emptying of solid foods from the stomach enabling people to tolerate normal foods and reducing dumping syndrome.
  • This is a pill-friendly operation. NSAIDS and Aspirin are well tolerated.
  • Because weight loss is achieved through stomach restriction as well as malabsorption, this surgery typically provides very predictable weight loss with great long-term weight loss maintenance.
  • Patients report experiencing significantly less malabsorptive symptoms compared to a standard duodenal switch because the common channel length is almost twice that of a standard DS.










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