PURPOSE:Almost two-thirds of the population undergoing bariatric surgery (BS) suffers from obstructive sleep apnea (OSA). Continuous positive airway pressure (CPAP) is the standard treatment for moderate to severe OSA and is recommended in patients undergoing BS perioperatively. A severe and dreaded complication after BS is anastomotic leakage. There is theoretical concern that perioperative CPAP use may result in increased distension of the gastrointestinal tract and increase the risk of developing an anastomotic leakage. The aim of this study was to evaluate the effect of postoperative CPAP use on the risk of developing anastomotic leakages after BS. METHODS:Retrospectively, all patients from a single bariatric center who underwent BS from November 2007 to August 2019 were included. Presence and severity of OSA were determined using poly(somno)graphy. To evaluate the effect of postoperative CPAP use on anastomotic leakage, a multivariable logistic regression analysis was performed. RESULTS:A total of 4052 patients were included, with OSA being diagnosed in 62%. Overall, 970 patients (24%) used CPAP after BS. Anastomotic leakage occurred in 64 (1.6%) patients after BS. Leakage rate was 1.3% in non-CPAP group versus 2.5% in CPAP group (p = 0.01). CPAP use was associated with anastomotic leakage; however, after adjustment, CPAP use was not an independent predictor (OR = 1.40, 95% CI 0.60-3.28, p = 0.44). CONCLUSION:There is no independent relation between postoperative CPAP use and anastomotic leakage after BS. Only revision surgery was an independent predictor of anastomotic leakage.