Single Anastomosis Stomach Ileal Bypass with Sleeve (SASI-S)
Basic Information
Single Anastomosis Stomach Ileal Bypass with Sleeve (SASI-S) is one of the newest bariatric procedures available in Australia.
It combines the benefits of a Gastric Sleeve with a single-loop bypass, achieving results comparable to the Duodenal Switch (SADI) while reducing long-term nutritional risks.
- Performed laparoscopically (keyhole surgery) under general anaesthetic
- Typically requires a 2-night hospital stay
- Designed to maximise weight loss, improve blood-sugar control, and preserve nutrient absorption
The stomach is first reshaped into a narrow sleeve, then joined (anastomosed) to a lower part of the small intestine so food can follow two paths — the new bypass (≈ 70%) and the normal route (≈ 30%).
Why Choose SASI-S?
Superior Safety
Unlike SADI, the duodenum (first part of the small bowel) is not divided, avoiding a more complex and risk-prone step.
Better Nutrient Absorption
The dual pathway allows improved absorption of vitamins and minerals, leading to fewer deficiencies and less diarrhoea than with standard bypass procedures.
Easily Reversible
If required, the SASI-S can be reversed to a standard Gastric Sleeve safely and simply.
Full Duodenal Access
Surgeons can still access the duodenum and bile duct with an endoscope if future procedures are ever needed (e.g. for gallstones).
Excellent Results
Early global data shows outstanding outcomes for Type 2 Diabetes remission and durable weight loss — making SASI-S one of the fastest-growing bariatric options worldwide.
The Surgery
The SASI-S operation is performed under general anaesthesia using laparoscopic (keyhole) techniques through five small incisions.
- A Sleeve Gastrectomy is performed to reduce stomach size.
- A single connection (anastomosis) is created between the bottom of the new sleeve and the small intestine (ileum).
- This allows food to travel through both the new bypass and the normal digestive route, balancing weight-loss efficiency with nutritional safety.
Am I a Candidate for SASI-S?
You may benefit from SASI-S if you:
- Have Type 2 Diabetes or metabolic syndrome
- Have a Body Mass Index (BMI) ≥ 45
- Are a non-smoker and ready to commit to ongoing follow-up care
- Have not achieved long-term success with diet, exercise, or medication alone
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Prior to Surgery
You will need to be on an ‘Ultra-low Calorie Diet’ before surgery. Optifast is taken for 2 weeks to replace ALL meals. If you feel you MUST have something else, then it needs to contain very few calories. (Salad or steamed vegetables without dressings or oil for a ‘treat’). Check with the nutritionist.
The usual stay in hospital is 2 post-operative nights.
Following Surgery
Day 1-4: Fluids that could be sucked through a thin straw.
Day 4-7 : thick fluids progressing to puree.
Week 2: Soft food like mash or scrambled eggs.
Week 3+: Gradual introduction of chewable food. Make sure you get enough protein.
Long-Term Care
- Daily multivitamin and mineral supplements for life (as with any bypass)
- Regular blood tests to monitor nutrients
- Balanced diet and ongoing support from your care team
General Advice
and possible minor side-effects
- Vomiting or discomfort
- Heartburn
- Bowel changes
Vomiting or discomfort
Often due to eating too quickly or swallowing air. Eat slowly, chew thoroughly, and stop when full.
Heartburn
Rare but manageable with medication.
Bowel changes
May occur early and improve as diet normalises.
Notify Dr Crawford if you experience persistent nausea, pain, or vomiting
Learn More
Dr Michael Crawford explains modern weight-loss surgery techniques, including the SASI-S procedure.
Frequently Asked Questions — SASI-S Weight Loss Surgery
1. What makes the SASI-S different from a regular Gastric Sleeve?
The SASI-S begins as a sleeve gastrectomy but adds a small intestinal bypass that lets food travel through two paths instead of one.
This dual-path design achieves stronger weight-loss and diabetes control results while reducing nutritional deficiencies compared with a standard sleeve.
2. How much weight can I expect to lose after SASI-S surgery?
Most patients lose between 70 – 85 % of their excess body weight within 12 – 18 months, provided they follow dietary and lifestyle guidance.
Results vary depending on age, initial BMI, and commitment to long-term habits.
3. Is the SASI-S procedure safe?
Yes. Because the duodenum isn’t divided, the SASI-S avoids one of the higher-risk steps seen in other bypasses.
Complication rates are low, and the operation is performed laparoscopically (keyhole surgery) for faster recovery and minimal scarring.
4. Will I still absorb vitamins and minerals normally?
The dual digestive pathway allows better nutrient absorption than traditional bypass operations.
You’ll still need daily multivitamins and routine blood tests, but deficiencies are generally less common than after SADI or standard Gastric Bypass.
5. Can the SASI-S be reversed or converted later?
Yes. The procedure can be safely reversed to a standard sleeve or adjusted to another form of bariatric surgery if needed.
This flexibility makes it one of the most adaptable modern bariatric options.
6. How long will I be in hospital and when can I return to normal activities?
Hospital stay is usually two nights, and most patients resume light daily activities within one to two weeks.
Full recovery—including return to work, exercise, and driving—typically occurs within three to four weeks, depending on individual healing and occupation.
An experienced Laparoscopic & Bariatric Surgeon helping patients lose weight through keyhole surgery since 2005.
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