The single-anastomosis duodenal-ileal bypass, also known as SADI-S, is one of the most powerful bariatric techniques for achieving weight loss. It is a good option for severely obese patients, either as a primary surgery or as a revision procedure after a failed sleeve gastrectomy. SADI-S is a laparoscopic procedure. It consists of two steps. In the first, called a “sleeve gastrectomy,” the stomach is shortened and narrowed like a tube to reduce the stomach’s capacity (almost 80% of the stomach is removed). In the second step, a bypass of the small intestine is made to reduce the surface area for food absorption. Specifically, the middle part of the small intestine is excluded from the transit of food. Therefore, after this second step, the first part of the small intestine, called the duodenum, connects to the distal small intestine (called the ileum). In summary, after this operation, food travels from the new small stomach to the distal intestine bypassing a long segment of the small intestine, which remains in the abdominal cavity, but is excluded from the food circulation. These anatomical changes decrease oral intake and reduce the absorption of ingested nutrients and calories. Patients who undergo this procedure can lose up to 80% of their excess weight in a year, weight loss that is generally maintained afterward.

It is a bariatric procedure with high success rates in the resolution of type 2 diabetes mellitus, dyslipidemia, hypertension and OSAHS. SADI-S is generally well tolerated. The frequency of bowel movements depends on the amount of fiber and water consumption. Some patients report bile reflux (bitter taste), in which case endoscopy is warranted. However, this technique is complex and surgical complications are more frequent than with other bariatric procedures. Plus, it could have other long-term side effects, such as vitamin deficiencies (specifically fat-soluble vitamins A, D, K, and E), calcium, zinc, and iron deficiencies, as well as an increased risk of protein and fatty acid hypo-absorption. To reduce these side effects, proper education and preparation of patients is mandatory before and after surgery. These include promoting healthy eating habits, exercise, and prescribing nutritional supplements. Finally, all patients should be closely followed by their GPs.