Sling Insertion Angle and Outcomes in Single-Incision Midurethral Sling Surgery (SUI-SLING)

Effect of Sling Insertion Angle on Surgical Outcomes and Quality of Life Following Single-Incision Midurethral Sling Surgery for Stress Urinary Incontinence

This study aims to evaluate the effect of sling insertion angle on surgical outcomes and quality of life in women with stress urinary incontinence (SUI) undergoing single-incision midurethral sling surgery.

Women diagnosed with urodynamic stress urinary incontinence who underwent surgery using a single-incision sling system were included. Patients were categorized into two groups based on sling insertion angle: an acute-angle group (<45°, resembling a retropubic trajectory) and a standard-angle group (approximately 45°, toward the obturator foramen).

The primary outcome was objective cure at 6 months, defined as a negative cough stress test without the need for additional anti-incontinence treatment. Secondary outcomes included objective cure at 1 and 3 months, postoperative voiding difficulty, persistent SUI symptoms, and quality of life assessed using the Incontinence Quality of Life (I-QOL) questionnaire.

This study provides clinical evidence on whether sling insertion angle influences early and mid-term outcomes following single-incision midurethral sling surgery.

Study Overview

• Status: Completed
• Conditions: Female Stress Urinary Incontinence; Stress Urinary Incontinence (SUI)

Detailed Description

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.

• Study Type: Observational
• Enrollment (Actual): 184

Contacts and Locations

Study Locations

• Taiwan
  • Taiwan
    • Taipei, Taiwan, Taiwan, 111
      • Shin Kong Wu Ho-Su Memorial Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Adult female patients diagnosed with urodynamic stress urinary incontinence who underwent single-incision midurethral sling surgery at a tertiary medical center. All procedures were performed by a single experienced surgeon, and patients had available follow-up data for at least 6 months.

Description

Inclusion Criteria:

• Female patients aged 18 years or older
• Diagnosis of urodynamic stress urinary incontinence (SUI)
• Preoperative 1-hour pad test >10 g
• Undergoing single-incision midurethral sling surgery (ContaSure Needleless system)
• Availability of complete clinical and follow-up data for at least 6 months

Exclusion Criteria:

• Presence of detrusor overactivity on urodynamic study
• Mixed urinary incontinence with predominant urge symptoms
• Voiding dysfunction
• History of prior pelvic or anti-incontinence surgery
• Neurological disorders affecting lower urinary tract function
• Pelvic organ prolapse stage ≥ III (POP-Q classification)

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Acute-angle sling group (<45°); Participants undergoing single-incision midurethral sling surgery with a sling insertion angle of less than 45 degrees, corresponding to a retropubic, TVT-like trajectory. This approach is hypothesized to provide earlier urethral support and improved early continence outcomes.
Standard-angle sling group (≈45°); Participants undergoing single-incision midurethral sling surgery with a standard sling insertion angle of approximately 45 degrees toward the obturator foramen. This represents the conventional transobturator-oriented trajectory used in routine clinical practice.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Objective cure rate at 6 months	Objective cure is defined as a negative cough stress test and no requirement for additional anti-incontinence treatment at 6 months after surgery.	6 months after surgery

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Objective cure rate at 1 and 3 months	Objective cure defined as a negative cough stress test without need for additional treatment at 1 and 3 months postoperatively.	1 month and 3 months
Postoperative voiding difficulty	Incidence of postoperative voiding difficulty requiring catheterization or clinical intervention.	Within 6 months after surgery
Persistent stress urinary incontinence symptoms	Presence of persistent subjective stress urinary incontinence symptoms reported by patients after surgery.	Up to 6 months
Quality of life measured by I-QOL score	Quality of life assessed using the Incontinence Quality of Life (I-QOL) questionnaire, with scores ranging from 0 to 100, where higher scores indicate better quality of life.	6 months

Collaborators and Investigators

• Sponsor: Shin Kong Wu Ho-Su Memorial Hospital

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2017
• Primary Completion (Actual): October 31, 2019
• Study Completion (Actual): October 31, 2019

Study Registration Dates

• First Submitted: April 8, 2026
• First Submitted That Met QC Criteria: April 8, 2026
• First Posted (Actual): April 15, 2026

Study Record Updates

• Last Update Posted (Actual): April 15, 2026
• Last Update Submitted That Met QC Criteria: April 8, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Stress urinary incontinence; Voiding dysfunction; I-QOL; Single-incision midurethral sling; Sling insertion angle; Objective cure
• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urination Disorders; Lower Urinary Tract Symptoms; Urological Manifestations; Urinary Incontinence; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Urinary Incontinence, Stress
• Other Study ID Numbers: SKH-20260203R-SUI

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) will not be shared due to patient privacy concerns and institutional restrictions. The data contain potentially identifiable clinical information, and sharing is not permitted under the approval of the Institutional Review Board. De-identified data may be available from the corresponding author upon reasonable request and with appropriate institutional approvals.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No