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Introduction: Urethral bulking therapy is an established minimally invasive treatment for female stress urinary incontinence (SUI), yet clinical outcomes vary considerably between patients despite standardized injection techniques. Differences in urethral pressure distribution may reflect distinct functional urethral phenotypes that influence treatment response and may also help identify individualized injection sites, as previously explored in a single study [1]. However, whether urethral pressure distribution can serve as a functional phenotyping tool to predict treatment response after bulking therapy remains unknown. The objective of this study is to evaluate whether preoperative urethral pressure profile characteristics are associated with improvements in symptoms and quality-of-life outcomes following proximal urethral bulking injection.

Methods: This exploratory retrospective study included women treated with urethral bulking therapy for urodynamic SUI between January 2024 and December 2025 at a tertiary referral center. Preoperative urethral pressure profile parameters were analyzed, including maximum urethral closure pressure (pclomax), closure pressure at 30% of urethral length (pclo30), and at 70% (pclo70). Ratios reflecting urethral pressure distribution were calculated (pclo30/pclomax, pclo70/pclomax, pclo70/pclo30). Clinical outcomes were assessed using the ICIQ-SF questionnaire and a quality-of-life (QoL) score. Treatment response was defined as ≥50% improvement in ICIQ-SF total score.

Results: Twelve patients with complete datasets were included. Seven patients (58%) achieved ≥50% improvement in ICIQ-SF score and were classified as responders. Responders tended to have lower baseline urethral closure pressures than non-responders. Greater quality-of-life improvement was associated with higher pclo30/pclomax ratios. ROC analysis identified a pclo30/pclomax cut-off value of 0.56 predicting greater QoL improvement (AUC = 0.81).

Conclusion: Preoperative urethral pressure distribution may represent functional urethral phenotypes associated with different response patterns following urethral bulking therapy. These preliminary findings suggest that urodynamic phenotyping could help guide individualized bulking injection strategies and warrant further evaluation in larger prospective studies.

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