Gastric Bypass to SADI-S Conversion

Roux-en-Y gastric bypass is one of the most effective weight-loss operations available (see Gastric Bypass (RYGB)). When it stops working, though, the choices are more complicated than after any other operation. Gastric bypass to SADI-S conversion takes apart the bypass and replaces it with a single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S). The small pouch is reconnected to the bypassed stomach, which is then reshaped into a sleeve. The duodenum is divided just past the pylorus, the stomach's natural valve, and joined to the ileum in a single connection. That leaves a long common channel, usually 250–300 cm, where food mixes with bile and digestive enzymes (Sanchez-Cordero et al., Obesity Surgery, 2025).

SADI-S was developed in 2007 as a simpler version of the duodenal switch. It keeps the sleeve and the connection just past the pylorus, but it removes the second intestinal connection and the mesenteric opening that goes with it. That cuts operative time and the risk of internal hernia (Pereira et al., Obesity Surgery, 2025). A channel shorter than 250 cm is no longer recommended because of higher malnutrition rates (Sanchez-Cordero et al., Obesity Surgery, 2025).

Results after conversion are strong and durable. In a 2026 cohort of patients converted to SADI-S after a prior bariatric operation, including gastric bypass, total weight loss was 36.4% at 1 year, 37.8% at 3 years, and 34.5% at 5 years. Only 2.9% failed to reach 20% total weight loss, and results were similar whatever the original operation (El-On et al., Obesity Surgery, 2026).

This is still a major reoperation. In national registry data on bypass-to-SADI-S conversions, the 30-day complication rate was 18.5%, the leak rate was 5.9%, and 7.2% needed reoperation. All three were statistically equivalent to conversion to duodenal switch (Serra et al., Surgical Endoscopy, 2026). Across nearly 95,000 conversions, those starting from a gastric bypass carried the highest risk, about 2.5 times the odds of a serious complication compared with converting a sleeve (Dallal et al., Surgery for Obesity and Related Diseases, 2026). The two-anastomosis alternative is covered on Gastric Bypass to Duodenal Switch (DS) Conversion, and every option is compared on the Gastric Bypass Revision for Weight Regain hub.

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The gastric bypass anatomy is taken down by reconnecting the gastric pouch to the remnant stomach. A sleeve gastrectomy is created or revised. The duodenum is divided just beyond the pylorus, and the ileum is connected to the duodenum in a single-anastomosis configuration. This enhances metabolic signaling and reduces calorie absorption.

Benefits include stronger metabolic improvement, improved weight loss durability, reduced hunger, improved satiety, and reversal of complications related to gastric bypass such as dumping syndrome.

• Gastric bypass patients with significant weight regain or inadequate weight loss. These are patients who have already tried nutrition counseling, anti-obesity medication, and less invasive options. Insufficient weight loss is the most common reason gastric bypass patients are converted to SADI-S (Surve et al., Obesity Surgery, 2021).

• Patients whose pouch and outlet are normal. If endoscopy and CT show the pouch and outlet are not the problem, adding malabsorption treats what is actually driving the regain. If the pouch or outlet is stretched, see Gastric Bypass Pouch Reduction or Transoral Outlet Reduction (TORe) first.

• Patients who want strong malabsorptive results with lower nutritional risk than a duodenal switch. In a randomized trial with 5-year follow-up, 7% of duodenal switch patients needed channel-lengthening surgery for malnutrition and 15% needed surgery for internal hernia. Neither occurred after SADI (Axer et al., Obesity Surgery, 2026).

• Patients with severe dumping syndrome along with weight regain. SADI-S restores the pylorus. In a small staged series, dumping resolved completely in one of two affected patients and partially in the other (Sánchez-Pernaute et al., Obesity Surgery, 2024). For dumping without weight regain, see Gastric Bypass Reversal.

• Patients whose diabetes, hypertension, or sleep apnea has come back. After revisional SADI-S, remission rates reached 69% for diabetes and 69% for sleep apnea (Esparham et al., Surgery for Obesity and Related Diseases, 2026).

• Patients who are nutritionally stable and committed to lifelong follow-up. Deficiency rates are directly linked to missed follow-up (Esparham et al., Obesity Surgery, 2023).

Who is usually better served by another operation:

• Severe reflux, erosive esophagitis, or Barrett's esophagus. Sleeve-based anatomy can bring reflux back, and GERD was reported in 5.1% of patients after revisional SADI-S (Esparham et al., Surgery for Obesity and Related Diseases, 2026). These patients usually do better keeping their bypass. See Gastric Bypass (Roux-en-Y) for GERD and Hiatal Hernia Repair After Gastric Bypass.

• Insulin-treated diabetes when maximal remission is the main goal. Five-year data suggest higher sustained remission after duodenal switch (63–68%) than after SADI (47–56%). Channel length may explain part of the difference (Axer et al., Obesity Surgery, 2026).

• Ulcers, strictures, pain, or excessive weight loss. These need a different operation. See Gastric Bypass Revision for Marginal Ulcer, Gastric Bypass Stricture Management, or Gastric Bypass Reversal for Malnutrition.

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The procedure is performed laparoscopically. The gastric bypass is reversed, the stomach is reshaped into a sleeve, and the duodenum is connected to the ileum in a single-anastomosis configuration. Most patients stay one night in the hospital.

Risks include bleeding, leak, stricture, nutritional deficiencies, diarrhea, bile reflux, and weight regain if long-term habits are not maintained. Revisional surgery carries higher complexity due to scar tissue and altered anatomy.

Days 1–3 focus on hydration, walking and pain control; week 1 is liquids, week 2 soft foods, and weeks 3–4 a gradual return to routine. By about 30 days most patients notice more energy, less hunger and early metabolic gains.

Patients typically experience stronger metabolic improvement and more durable fat loss compared to gastric bypass alone. Weight loss occurs steadily over 12–18 months.

More in Gastric Bypass Revisions

Related procedures: Gastric Bypass to MagDI Conversion, Gastric Bypass to OAGB Conversion, Transoral Outlet Reduction, Gastric Bypass Revision for Weight Regain, Gastric Bypass Pouch Reduction, Gastric Bypass Limb Lengthening. Related primary operations: Gastric Bypass, SADI-S. For an overview of all options, see Revisional Bariatric Surgery.

Conditions this SADI-S conversion relates to: Weight Regain, Inadequate Weight Loss, Post-Bariatric Hypoglycemia, Marginal Ulcer, Dumping Syndrome, Internal Hernia.

Converting a gastric bypass to SADI-S means undoing one operation and building another, often through years of scar tissue. National data show that revisions after a prior gastric bypass carry the highest risk of any bariatric conversion, and that this excess risk has not decreased over time (Dallal et al., Surgery for Obesity and Related Diseases, 2026). The leak rate after bypass-to-SADI-S conversion is higher than after a primary SADI-S (Serra et al., Surgical Endoscopy, 2026). In this setting, judgment and technique matter more than in almost any other bariatric operation.

Dr. Nestor de la Cruz-Muñoz, MD, FACS, DABOM, has spent his career performing and revising gastric bypasses and duodenal switch operations. He is a board-certified surgeon and a diplomate of the American Board of Obesity Medicine, so he treats obesity both medically and surgically. He also served for 10 years as a fellowship program director, training other surgeons in the reoperative techniques these cases demand.

His program offers every bypass revision option in one place:

• Transoral Outlet Reduction (TORe)

• Gastric Bypass Pouch Reduction

• Gastric Bypass Limb Lengthening

• Gastric Bypass Distalization

• Gastric Bypass to MagDI Conversion

• Gastric Bypass to Duodenal Switch (DS) Conversion

• SADI-S conversion

• Anti-obesity medication

With all of these available, the choice between SADI-S and the alternatives is based on your anatomy, reflux status, diabetes, and nutrition, not on which operation the surgeon happens to offer. That includes deciding whether a one-stage or staged approach is safer for you. Every plan starts with a complete anatomic, reflux, and nutritional workup, and lifelong lab monitoring is built in from day one.

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Rebuilding a gastric bypass as a SADI-S demands careful reoperative technique. Dr. de la Cruz-Muñoz has performed bariatric surgery for over 25 years and has completed more than 9,000 bariatric operations, a volume few surgeons reach.

In a 2026 cohort of patients converted to SADI-S after a prior bariatric operation, including gastric bypass, total weight loss was 36.4% at 1 year, 37.8% at 3 years, and 34.5% at 5 years (El-On et al., Obesity Surgery, 2026). Results depend on adherence to nutrition, activity, and follow-up.

SADI-S conversion offers powerful improvement in type 2 diabetes, insulin resistance, hypertension, dyslipidemia, sleep apnea, and fatty liver disease.

To keep the weight off after SADI-S conversion, focus on protein-forward eating, resistance training, no slider foods, preserved muscle and regular metabolic follow-up, with body composition monitoring as an essential tool.

SADI-S may improve reflux in some patients but may worsen it in others. Patients with severe GERD usually do better keeping their gastric bypass than converting to SADI-S. Hiatal hernia repair is performed when needed.

Future revision options include limb length adjustments, sleeve tightening, or conversion to full duodenal switch (DS) for maximal metabolic effect.

Lean mass is a priority after SADI-S conversion. Patients are guided to emphasize protein, keep up resistance training and hydration, and monitor body composition over time.

Insurance coverage for converting a bypass to SADI-S varies. Plans may require documentation of inadequate weight loss, metabolic disease or bypass-related complications.

To prepare for SADI-S conversion, you may need bloodwork, imaging, an upper endoscopy, a nutrition consult, a psychological evaluation, and adjustments to current medications.

Following SADI-S conversion, nutrition moves from clear liquids to full liquids, then purees, soft foods and regular textures. Daily protein targets and vitamin supplements are essential.

You will be walking within hours of the SADI-S conversion. Light activity is the rule through week 2, and resistance training generally begins at about weeks 4–6.

Pre-operative testing for bypass-to-SADI-S conversion is consolidated into the first one or two days after arrival. Most international patients stay approximately one week in total. Follow-up visits and lab reviews continue virtually.