Effects of body position on high-resolution manometry parameters and their correlations with symptoms.

High-resolution manometry (HRM) is essential for evaluating esophageal motility, and the Chicago Classification ver. 4.0 recommends measurements in both supine and upright positions. However, the impact of body position on HRM metrics and their relationship with symptoms has not been fully clarified. In this retrospective observational study, 287 patients undergoing HRM were categorized into postoperative, disorders of esophagogastric junction outflow (DEO), peristaltic disorders, and normal motility groups. Integrated relaxation pressure (IRP), distal contractile integral (DCI), and intrabolus pressure (IBP) were assessed in both positions, and symptom severity was evaluated using the Eckardt score, Gastroesophageal Reflux Disease Questionnaire (GerdQ), and Hospital Anxiety and Depression Scale (HADS). IRP and DCI were significantly lower in the upright position, whereas IBP showed no positional difference. In the DEO group, IRP correlated with the Eckardt score in both positions, with a slightly stronger correlation in the supine position. Reflux and anxiety symptoms also correlated with the Eckardt score, suggesting interactions between motility impairment, reflux, and psychological factors. Although HRM metrics varied by position, neither position was clearly superior for explaining symptoms. HRM in both supine and upright positions remains essential for comprehensive clinical assessment.