OAGB to SADI Conversion

Most patients do well after a one-anastomosis gastric bypass (OAGB), but a subset later need revision for weight, metabolic disease or bile reflux.

Converting OAGB to SADI-S (single-anastomosis duodeno-ileal bypass with sleeve gastrectomy) is an option for patients with inadequate weight loss, weight regain, or bile reflux after OAGB who would benefit from a stronger metabolic operation. SADI-S provides much of the power of the duodenal switch with only one intestinal connection, and it preserves the pylorus.

Patients from across the country are referred to Dr. de la Cruz-Muñoz for complex revisions; he has performed bariatric surgery for over 25 years and completed more than 9,000 bariatric operations. Every OAGB-to-SADI-S plan is built around your anatomy, symptoms and nutrition.

Why OAGB Sometimes Needs Revision

The mini gastric bypass (OAGB) joins a long, narrow stomach pouch to an intestinal loop roughly 150–200 cm downstream. It is effective and widely used, though the single loop can lead to three well-described long-term issues: bile reflux into the pouch and esophagus, nutritional deficiency when the bypassed (biliopancreatic) limb is too long relative to total bowel length, and weight regain in some patients. SADI-S can address both regain and bile reflux.

Converting to a SADI-S involves several steps:

• The OAGB gastrojejunostomy is taken down and the intestinal loop restored.
• The stomach is reconstructed as a sleeve gastrectomy.
• The duodenum is divided beyond the pylorus and connected end-to-side to a loop of ileum, usually 250–300 cm from the end of the small intestine, after the bowel is measured.

Bile no longer reaches the stomach pouch, which is why SADI-S can also address bile reflux. Because the sleeve remains, significant acid reflux must be considered.

The SADI-S common channel is chosen after measuring the whole small intestine, because bowel length varies widely between people and is key to how safe and effective the conversion will be.

Matching the OAGB Revision to the Problem

• Bile or acid reflux: conversion to Roux-en-Y gastric bypass or a bile reflux revision; SADI-S also diverts bile but keeps a sleeve, so acid reflux must be weighed
• Malnutrition: usually a limb-length revision, a Roux-en-Y conversion with a shorter limb, or conversion to sleeve gastrectomy, rather than a more malabsorptive operation
• Weight regain or persistent diabetes: conversion to SADI-S (this page), conversion to duodenal switch when maximal effect is needed, or limb lengthening
• Ulcers or hypoglycemia: options include pouch revision, Roux-en-Y conversion, or a sleeve conversion

Many patients have overlapping problems, and the chosen operation needs to address them together.

• Strong weight loss and diabetes improvement with a single intestinal connection
• Pylorus preserved, with little dumping and lower ulcer risk
• Removes bile from the stomach pouch
• A longer common channel than a classic DS, which is gentler on nutrition
• Shorter operation than a full duodenal switch

• Insufficient weight loss or regain after OAGB with good nutrition
• Persistent type 2 diabetes or fatty liver
• Bile reflux after OAGB without significant acid reflux
• Commitment to lifelong supplements and labs

For patients whose main problem is reflux, Roux-en-Y conversion is usually better. For maximum effect, a duodenal switch may be considered.

Before SADI-S conversion, patients who smoke must quit and nutrition is brought up to target. Much of the work-up can be done by telehealth for out-of-town patients.

1. Laparoscopic or robotic access under general anesthesia
2. Takedown of the OAGB anastomosis and restoration of continuity
3. Sleeve gastrectomy construction
4. Duodenal division and single duodeno-ileostomy at the measured distance
5. Leak testing, mesenteric closure and hiatal hernia repair

The SADI-S conversion is typically completed with small incisions in about two to four hours, with the exact time depending on scar tissue and complexity.

• Revisional surgical risks: leak at the new connection, bleeding, infection, blood clots and anesthesia risk, somewhat higher than in a first-time operation
• Nutritional deficiencies related to the new malabsorptive anatomy, which require lifelong supplements and regular labs
• Internal hernia, reduced by closing mesenteric defects
• Weight change in either direction, depending on the revision

• Hospital stay: usually one to two nights.
• Diet: a staged return from clear liquids and protein shakes to pureed, soft and then regular foods over about four to six weeks.
• Activity: same-day walking, desk work after about two weeks, and no heavy lifting for four to six weeks.
• Supplements and labs: lifelong bariatric multivitamin, calcium, vitamin D, B12 and iron as directed; nutrition labs are drawn at 3, 6 and 12 months and every year after.
• Travel: out-of-town patients should plan to stay in Miami for approximately one week.

Most patients achieve meaningful additional weight loss and better metabolic control over the next one to two years. Supplements, yearly labs and a protein-focused diet keep nutrition on track.

To find out whether conversion to a SADI-S is right for you, call 305-692-0392.

What the Research Shows

• In YOMEGA, a randomized trial, OAGB using a 200 cm bypassed limb gave weight loss comparable to Roux-en-Y bypass but with more nutritional adverse events (Robert et al., The Lancet, 2019). The IFSO 2021 position statement on OAGB reviews data showing that a 150 cm limb yields similar weight loss to 200 cm (De Luca et al., Obesity Surgery, 2021).
• After a failed band, a single-anastomosis duodenal switch produced more weight loss than conversion to sleeve, without more early complications (Pearlstein et al., Obesity Surgery, 2019). Data specific to OAGB-to-SADI-S conversion remain limited.

More in OAGB Revisions

Related procedures: OAGB to Duodenal Switch Conversion, One-Anastomosis Gastric Bypass, OAGB to Gastric Bypass Conversion, OAGB Revision for Bile Reflux, OAGB Limb Length Revision, OAGB to Sleeve Conversion. Related primary operations: SADI-S. For an overview of all options, see Revisional Bariatric Surgery.

Conditions addressed by OAGB revision: Weight Regain, Bile Reflux, Marginal Ulcer, Malnutrition After Bariatric Surgery.

Dr. Nestor de la Cruz-Muñoz is a nationally recognized bariatric and metabolic surgeon with extensive experience in complex revisional surgery and advanced metabolic procedures such as SADI-S. He applies that expertise with the goal of a safe OAGB takedown and precise SADI-S reconstruction.

With more than 9,000 bariatric operations completed over a career of over 25 years, Dr. de la Cruz-Muñoz has a volume of experience few surgeons reach, and he applies it to each OAGB-to-SADI-S plan.

Research and Publications

Dr. de la Cruz-Muñoz's published and presented work on this topic includes:

• Haidar Ahmad H, de la Cruz-Muñoz N. Revisional surgery outcomes. Poster presentation, ObesityWeek, 2013.
• Invited lecture: “Reversals and Elongations.” 3rd Annual International Symposium on Magnetic Gastrointestinal & Colon Surgery, Montreal, 2025.

When weight regain was present, the amount of additional weight loss varies from patient to patient.

Converting OAGB to SADI-S provides powerful improvement in type 2 diabetes, insulin resistance, hypertension, dyslipidemia, sleep apnea and fatty liver disease, and many patients see their metabolic numbers improve quickly.

Durable SADI-S results depend on protein-forward meals, resistance training, avoiding slider foods, keeping muscle mass and steady metabolic follow-up. Monitoring body composition is essential to prevent metabolic slowdown.

SADI-S may improve reflux in some patients but may worsen it in others. Patients with severe GERD or esophagitis may benefit more from conversion to gastric bypass. Hiatal hernia repair is performed when needed.

Should more be needed after OAGB-to-SADI-S, options include adjusting limb lengths, tightening the sleeve, or completing a full duodenal switch (DS) for maximal metabolic impact.

Because SADI-S adds malabsorption, protecting lean mass is essential. Patients are coached to emphasize protein, train with resistance, stay hydrated and monitor body composition to protect metabolic rate.

Most insurers cover revisional surgery when medical necessity is documented, including bile reflux, metabolic failure, or inadequate weight loss. Requirements may include imaging, endoscopy, and medical clearance.

Before SADI-S conversion, patients may need bloodwork, imaging, endoscopy, a nutrition consultation, a psychological evaluation and medication changes; higher-risk patients may need additional testing.

After SADI-S conversion, the diet steps up from clear liquids to full liquids, purees, soft foods and regular textures. Meeting protein goals and taking vitamins daily are essential to prevent deficiencies.

Early walking begins immediately after surgery. Light activity continues through week 2. Resistance training typically begins at week 4–6 to support muscle preservation and metabolic health.

Traveling with a companion is recommended for SADI-S conversion, especially during the first days after surgery. Plan to stay approximately one week. Supplement guidance and lab reviews continue virtually after you return home.