Sleeve Gastrectomy Leads to Immediate, Significant Intraoperative Increase in Lower Esophageal Distensibility and Opening Area

<b>Background/Objectives:</b> Functional impairment of the complex motility system in the upper gastrointestinal tract is high in patients suffering from obesity and even higher after metabolic bariatric surgery (MBS). Sleeve gastrectomy (SG) and gastric bypass (GB) represent the most common MBS procedures worldwide. Despite procedural standardization, no diagnostic method is able to depict the functional consequences resulting from intraoperative anatomical changes during MBS. This pilot study was conducted to reveal immediate intraoperative functional effects of MBS on the anti-reflux barrier in SG and GB. <b>Methods:</b> A prospective analysis was performed on consecutive patients with informed consent for MBS. A standard protocol for each procedure was established prior to study onset to analyze functional parameters at the lower esophageal sphincter (LES). Measurements were conducted intraoperatively during minimally invasive SG and GB. Distensibility index (DI), intra-balloon pressure, diameter (Dmin), and minimal cross-sectional area (CSA) at the LES served as points of interest for analyzation. <b>Results:</b> Intraoperative evaluation was performed successfully in 40 patients and no directly related adverse events were reported. DI and Dmin intraoperatively significantly increased immediately in SG (2.1 mm²/mmHg (±0.5) vs. 2.9 mm²/mmHg (±1.3), 95% CI: -1.6 to -0.14, <i>p</i> = 0.023 and 12.0 mm (±1.2) vs. 13.9 mmH (±2.8), 95% CI: -3.6 to -0.2, <i>p</i> = 0.028, respectively) whereas GB did not affect functional measurements. <b>Conclusions:</b> Sleeve gastrectomy immediately and significantly influences the LES and increases the opening area whereas gastric bypass surgery appears not to influence LES distensibility or opening diameters. Intraoperative standardized EndoFLIP^TM measurements are feasible and safe and add additional real-time information during MBS.