Sling Insertion Angle and Outcomes in Single-Incision Midurethral Sling Surgery

This prospective cohort study was conducted at a tertiary medical center and included women with urodynamic stress urinary incontinence (SUI) who underwent single-incision midurethral sling surgery between October 2017 and October 2019. All procedures were performed by a single experienced surgeon using a standardized surgical technique with the same sling system. Patients were classified into two groups according to sling insertion angle: the acute-angle group (\<45°), representing a trajectory similar to the retropubic approach, and the standard-angle group (approximately 45°), directed toward the obturator foramen. The sling angle was assessed intraoperatively based on the orientation of the insertion instrument. Inclusion criteria included women with confirmed urodynamic stress incontinence and a preoperative 1-hour pad test result greater than 10 grams. Exclusion criteria included detrusor overactivity, mixed urinary incontinence, prior pelvic surgery, voiding dysfunction, neurological disease, and pelvic organ prolapse stage III or higher. The primary outcome was objective cure at 6 months postoperatively, defined as a negative cough stress test and no requirement for additional anti-incontinence treatment. Secondary outcomes included objective cure rates at 1 and 3 months, postoperative voiding difficulty, persistent SUI symptoms, and quality of life assessed using the validated Incontinence Quality of Life (I-QOL) questionnaire. Postoperative follow-up evaluations were conducted at 1, 3, and 6 months. Clinical outcomes and complications were systematically recorded and analyzed to determine whether sling insertion angle affects surgical efficacy and patient-reported outcomes. The study was approved by the Institutional Review Board of Shin Kong Wu Ho-Su Memorial Hospital, and all procedures were conducted in accordance with the Declaration of Helsinki.