Conversion from one-anastomosis gastric bypass to Roux-en-Y gastric bypass: when and why-a single-center experience of all consecutive OAGB procedures

Background: One-anastomosis gastric bypass (OAGB) is a well-established treatment method in patients with morbid obesity. Its long-term impact on de novo reflux, anastomotic complications, and malnutrition needs further evaluation. Roux-en-Y gastric bypass (RYGB) is a technically feasible procedure in revisional bariatric surgery. This study presents our institutional data on conversion from OAGB to RYGB.

Objective: To determine the reasons for conversion, preoperative endoscopic findings, and feasibility of revisional bariatric surgery after OAGB.

Setting: University hospital in Austria METHODS: Retrospective analysis of a prospectively fed database. All patients undergoing OAGB between January 2012 and December 2019 were included. Screening was carried out for all patients needing conversion to RYGB. Percent total weight loss, percent excess weight loss, time to conversion, postoperative complications, and reasons for conversion were assessed.

Results: Eighty-two of 1,025 patients who underwent OAGB were converted laparoscopically to RYGB. Seven patients were converted early because of anastomotic/gastric tube leakage. Median time to late conversion was 29.1 ± 24.3 months, mean percent excess weight loss was 86.6% ± 33.1% and percent total weight loss was 35.1% ± 13.5%. Forty-two patients were converted because of reflux, 11 because of persistent marginal ulcers, 10 because of anastomotic stenosis, 9 because of malnutrition, and 3 because of weight regain. Seven patients showed Barrett's metaplasia in biopsies at the gastroesophageal junction before conversion.

Conclusion: Laparoscopic conversion from OAGB to RYGB is technically feasible with a moderate rate of postoperative complications. Severe (bile) reflux is a serious long-term complication after OAGB, with 4.1% of patients needing conversion to RYGB. Endoscopy after OAGB in patients showing clinical symptoms of gastroesophageal reflux disease is strongly advised to detect underlying pathologic changes.