Esophageal high-resolution manometry and 24 h pH-impedance monitoring normative values in patients with obesity candidate for bariatric and metabolic surgery

Obesity is linked to increased risk of gastroesophageal reflux disease (GERD) and esophageal motility disorders, both of which may impact outcomes in metabolic and bariatric surgery (MBS). GERD pathophysiology in obesity includes elevated intraabdominal pressure and altered esophagogastric junction (EGJ) function. High resolution manometry (HRM) and 24-h esophageal pH-impedance (MII-pH) monitoring are vital in evaluating GERD, yet normative values specific to populations with obesity are limited, risking misdiagnosis if lean data are used. This study establishes normative HRM and MII-pH values in asymptomatic individuals with obesity, compared to normal-weight controls, to guide accurate diagnosis and treatment. A retrospective analysis was conducted on asymptomatic patients with obesity (BMI >= 30) and normal-weight controls (BMI 20-25) who underwent HRM and MII-pH prior to MBS between 2015 and 2024. Exclusion criteria included GERD symptoms, esophagitis, and prior gastrointestinal surgery. Key HRM parameters (LES pressure, EGJ morphology) and MII-pH metrics (acid exposure time, reflux episodes) were recorded and analyzed. Of the 96 patients with obesity and 25 normal-weight participants, significant differences in HRM and MII-pH results were observed. Individuals with obesity showed increased intra-gastric pressure, gastroesophageal pressure gradient, and higher acid exposure time. While LES pressure and EGJ morphology were similar to controls, participants with obesity exhibited distinct reflux patterns, especially postprandial, suggesting obesity-specific physiological changes. This study establishes normative HRM and MII-pH values for asymptomatic individuals with obesity, highlighting critical differences from normal-weight controls. Obesity-specific diagnostic criteria are essential for accurate GERD diagnosis, particularly for MBS candidates, to improve management and predict potential postoperative complications.