Background <p>One anastomosis gastric bypass (OAGB) is the third most common metabolic bariatric surgery. Early anastomotic failure is uncommon and may necessitate re-operation. The most common re-operative strategy is peritoneal washout and drainage, while the preferred reconstructive approach is conversion to Roux-en-Y gastric bypass (RYGB). Reversal to normal anatomy in this emergency setting is extremely rare. We present a detailed single-patient emergency OAGB reversal for a leak with operative video, addressing a gap in the published literature.</p> Case Presentation <p>A 28‑year‑old woman with BMI 36.2&#xa0;kg/m² without comorbidities underwent laparoscopic OAGB. Two weeks later, she presented with abdominal pain, nausea, and vomiting. Computerized tomography (CT) demonstrated free air and perianastomotic fluid without contrast extravasation. Laparoscopy revealed anastomotic dehiscence with murky bile-stained fluid largely walled off by the liver. After taking down the anastomosis, a markedly distended gastric remnant prevented RYGB reconstruction. As the patient became unstable, reversal of OAGB was performed as a salvage procedure. Post‑operatively she required intensive care and parenteral nutrition. An intraluminal drain–related leak was diagnosed and managed endoscopically by drain repositioning. She resumed oral intake gradually and was discharged in good condition. At two weeks she tolerated a soft diet. At six months she reported intermittent vomiting with solids, though CT and endoscopy were unremarkable and symptoms improved with dietary modification.</p> Conclusion <p>Early anastomotic dehiscence after OAGB may require urgent surgical intervention. When re‑anastomosis or conversion to RYGB is unfeasible and the patient is unstable, reversal to normal anatomy can serve as a salvage option.</p> Graphical Abstract <p></p>