Advancing bariatric surgery: evaluating SASI bypass as a safe and effective revisional option for post-SG weight regain—a 24-month follow-up study

Sleeve gastrectomy (SG) is the most common bariatric surgery, but weight regain and metabolic relapse require revisional procedures. The Single Anastomosis Sleeve Ileal (SASI) bypass is a promising revision, providing metabolic benefits and lasting weight loss while maintaining physiological advantages. This study assesses the effectiveness, safety, and metabolic effects of the SASI bypass as a revisional procedure for patients with weight regain or insufficient weight loss after SG. A prospective case series at five centers (2021–2025) involved 39 participants with prior SG and weight regain, who underwent SASI bypass and were monitored for 24 months. Primary outcomes included weight loss trajectories (%TWL, %EWL, %EBMIL) and resolution of comorbidities (diabetes, hypertension, hyperlipidemia, GERD, and sleep apnea)—secondary outcomes assessed postoperative complications, classified by Clavien-Dindo criteria. Significant weight loss was observed at 6, 12, and 24 months, with an average %EWL of 79.99% at 24 months. All weight trajectories showed a significant difference after 24 months. ( p < 0.001) Comorbidity resolution rates were notably high, exhibiting strong statistical significance ( p < 0.001). The SASI bypass exhibited a favorable safety profile, with complications noted in 15.4% of participants, predominantly minor and self-limiting. Additionally, two individuals required revision surgery back to SG as a result of severe malnutrition and EWL exceeding 100%. SASI bypass offers a safe, effective revisional option for weight regain after SG, with metabolic benefits, lasting weight loss, and fewer malabsorptive risks. However, long-term studies and larger trials are needed to confirm these results and improve patient selection.