The bypass with sleeve gastrectomy procedure, also known as SADI-S, is a promising bariatric surgery procedure.
SADI-S stands for ‘Single Anastomosis Duodeno–Ileal Bypass with Sleeve Gastrectomy’.
Initial studies indicate it provides greater weight loss than a standard gastric bypass or sleeve gastrectomy without increased complications. SADI-S is being offered to selected patients with full disclosure to enable them to make an informed decision.
How SADI-S works
SADI-S is a modified version of an operation that was developed 30 years ago, formally called Biliopancreatic Diversion with Duodenal Switch (BPD-DS) and more simply known as the duodenal switch.
The SADI-S procedure involves two steps:
- Step one; the surgeon will perform a sleeve gastrectomy, removing about 80% of the stomach.
- Secondly, the first part of the intestine (duodenum) is divided just below the stomach and reattached (anastomosed) to a loop of intestine about 2 metres further downstream.
This two-step procedure effectively bypasses food from the metabolically active part of the intestine, lessening the total length of the intestinal loop where nutrients are absorbed. The procedure results in decreasing the patient’s appetite, restricting meal sizes, and hormonal changes which have a positive effect on the body’s metabolism.
What are the potential advantages of the SADI-S procedure?
- Delivers greater weight loss than a sleeve gastrectomy or standard gastric bypass, which is advantageous for people with a BMI above 50.
- Provides a more powerful metabolic effect than a sleeve gastrectomy or standard gastric bypass, which is advantageous for people with poorly controlled Type 2 Diabetes.
- Can be performed on people who have already had a sleeve gastrectomy, which is advantageous for people who experience weight regain or insufficient weight loss.
- Lowers the risk of diarrhea and nutritional deficiencies often encountered with a conventional duodenal switch.
- Connecting a loop of small bowel rather than a Roux limb is anticipated to reduce the long-term risk of intestinal obstruction, compared to a standard gastric bypass and compared to a duodenal switch.
- The pylorus is retained above the connected loop of small bowel and continues to regulate the rate at which food and acid empty from the stomach into the intestines and to prevent free reflux of bile into the stomach. This helps to reduce the likelihood of certain problems encountered with gastric bypass surgery such as: Dumping Syndrome, unstable blood sugar fluctuations (reactive hypoglycaemia, nocturnal hypoglycaemia), food restrictions and intolerance, marginal ulcers.
What could be potential disadvantages of the SADI-S procedure?
The SADI-S surgical risks are very similar to most other bariatric techniques:
- Intestinal perforation
- Anastomotic leaks
- Venous thrombosis and pulmonary embolism
- Chance of bile reflux
- In the long term it could produce a bowel obstruction
Even though SADI-S is a promising procedure, it is still relatively new compared to the more established procedures available in bariatric surgery. At present, four published studies are available worldwide totalling 222 patients. Three of the four studies are from a single institution as an ongoing cohort. There is no published data past five years.
What are the results of the SADI-S procedure?
We do not have long term follow up on large numbers of patients, but the initial combined results of SADI-S are very good.
Initial results include a retrospective analysis of 123 patients with an average BMI of 49.4 who underwent the SADI-S procedure between January 2013 and July 2014:
- 72% excess weight lost at one year
- No bowel obstructions
- One marginal ulcer
- One re-operation
To put this into perspective, at one year, a similar group (sample size and BMI range) of patients with obesity would be expected to have lost:
- 48% of excess weight following a sleeve gastrectomy
- 55% of excess weight following a standard gastric bypass, with an expected morbidity of
- Around 2 bowel obstructions
- Around 5 marginal ulcers
- Around 5 re-operations
The questions are whether these excellent results will remain constant over time, whether they will be reproducible by other units and whether larger numbers will reflect the same figures. Other units are also starting to report their experience. Another unit in the US has recently reported their first 100 cases with similar good results.
A double-blinded randomised study is currently being conducted in Quebec City, Canada, comparing SADI-S to the Duodenal switch.
Surgeons across the world are following the progress in this field with great interest and it was discussed in depth at the First Duodenal Switch Consensus Conference held in Quebec City, Canada in June 2016.
Take Home Message
It takes individuals (patients and surgeons) willing to go forth with a fairly new procedure to make progress in medicine.
We offer SADI-S to selected patients after full disclosure of the current status of the procedure. All patients are assessed and followed up long-term by a multidisciplinary team with similar protocols as units performing the duodenal switch.