Second-Generation Radiofrequency and Targeted Therapeutic Exercise for Stress Urinary Incontinence Due to Urethral Hypermobility: A Study Protocol

Background: Stress urinary incontinence (SUI) is defined as involuntary urine loss during activities that increase intra-abdominal pressure. It is highly prevalent among women and significantly affects physical, emotional, and social well-being. Pelvic floor muscle training (PFMT) is the gold-standard conservative therapy. Second-generation radiofrequency (RF) therapy has shown promise as an alternative. It stimulates collagen synthesis and promotes tissue remodeling. This study will compare the effects of PFMT, RF, and their combination on pelvic floor function, urethral stability, and health-related quality of life (HRQoL) in women with SUI due to urethral hypermobility. Methods/Design: This will be a single-blinded, three-arm, randomized controlled trial conducted at Clínica Traña (San José, Costa Rica). Women aged ≥18 years with clinically confirmed SUI and a retrovesical (β) angle ≥ 140° during the Valsalva maneuver on functional transperineal ultrasound will be randomized (1:1:1) to PFMT (16 weeks, twice-weekly supervised sessions), RF (5 weekly sessions using Capenergy® C500 Urogyne), or combined RF + PFMT (39 per arm; total N = 117 accounting for 30% attrition). The primary outcome is the change from baseline in pelvic floor muscle strength at 12 months post-intervention, measured by the modified Oxford scale and vaginal manometry. Secondary outcomes will include urethral stability (retrovesical β angle and bladder neck descent on ultrasound), incontinence severity (Sandvik Severity Index), and HRQoL (ICIQ-UI SF and King’s Health Questionnaire). All outcomes will be assessed at baseline, immediately post-intervention, 15 days, 3 months, 6 months, and 12 months follow-up. Assessments will be performed by blinded evaluators. Analysis will follow intention-to-treat principles using repeated-measures ANOVA or non-parametric equivalents (SPSS v.29; p < 0.05). The trial was prospectively registered on ClinicalTrials.gov (NCT07095283, registered on 24 July 2025), prior to the recruitment of the first participant. Expected outcomes: This study will provide comparative effectiveness data on whether the addition of RF to PFMT offers additional benefits over PFMT alone in the management of SUI.