**4.5 Single anastomosis duodenal switch (SADI)**

SADI is a simplification of the BPD- DS. The procedure has two main components: a sleeve gastrectomy preserving the pylorus and a single duodenoenterostomy. After the SG is created and the duodenum transected, a duodenoileal anastomosis between

the proximal duodenum and a loop of the ileum) is done by replacing the Roux-en-Y reconstruction with a single-anastomosis. The length of the common channel is increased to 300 cm from the ileocecal valve.

These modifications were developed to reduce the main drawbacks of the BPD- DS which include technical considerations with constructing a Roux-en-Y configuration with 2 anastomosis and side effects from having an ultra-short length of the common channel. The rearrangement to the loop configuration may also benefit absorption since it changes the flow of the biliopancreatic secretions that before were diverted distally. While the length of the common channel must be no less than 300 cm, the size of the sleeve may vary. It does not have to be as restrictive as with an SG as a single procedure, avoiding side effects regarding limitations in food ingestion and rapid emptying into the small bowel.

SADI, compared with other classic hypoabsorptive metabolic surgeries is technically simpler with only one anastomosis, has a restrictive and hypoabsorptive component favoring weight loss and obesity-related comorbidities improvement, and the preservation of the pylorus avoids post gastrectomy symptoms. As with the other surgical procedures, possible complications are related to hemorrhage, anastomotic leakage, and strictures. Nutritional deficiencies are still a possible side effect and vitamins and minerals supplementation must be monitored and taken accordingly, but the creation of a 300 cm common channel has significantly improved the issue of malnutrition (**Figure 5**).

The field of bariatric surgery is constantly changing as new studies are being developed with the aim of having a better understanding of the molecular changes associated with these procedures. Hopefully, this will lead to the advent of new treatments with higher benefits and lower risks, allowing for better and tailored therapies. One of the fields of interest is the role of bile acids as a signaling molecule for different plasma membrane and nuclear receptors given their favorable metabolic effects related to weight loss and glucose tolerance after surgery. Adipose tissue circulating micro RNAs (miRNAs) are also being studied as there is evidence showing that

*Duodenal Exclusion: Indications and Clinical Considerations DOI: http://dx.doi.org/10.5772/intechopen.108516*

alterations in their profile may change the gene expression and reduce the activation of inflammatory mediators thus improving insulin signaling [27]. In addition, due to the favorable impact that bariatric surgery has shown in improving or resolving diseases that are correlated with higher morbidity and mortality, the possibility of broadening the indications and including patients with lower BMI before the development of obesity-related metabolic complications should be considered.
