Intraoperative Ultrasound Evaluation of Mid-Urethral Sling with and without Apical Suspension

Objectives: Midurethral sling (MUS) is the most commonly used surgical treatment for stress urinary incontinence (SUI). The success of MUS may depend on the urethral length as well as the sling positioning. Sling positioning along the urethra may also be affected by a concurrently performed apical prolapse repair. Our study aimed to compare differences in the midurethral sling positioning using a trans-labial ultrasound intraoperatively in women who only had MUS placed versus those who underwent apical prolapse repair at the same time and to determine how this difference correlated to symptoms post-operatively.

Methods: In this prospective cohort study, we compared sling position between women undergoing MUS alone vs when placed concurrently with any apical support procedure using intraoperative translabial ultrasound. All MUS were placed after the apical suspension. Translabial ultrasound images were obtained intraoperatively at the beginning of the case, after apical suspension (if applicable) and after sling placement. Two reviewers who have experience in translabial ultrasound independently reviewed the images and obtained measurements of the urethral length, sling positioning along the urethra and the angle of the urethra to the pubic symphysis (Figure 1). Their measurements were then averaged for calculations and statistical analysis. The Urinary Distress Inventory (UDI-6) scores were also compared pre- and post-operatively between the groups.

Results: Fifty-five patients were enrolled in the study and 51 met the image quality criteria for inclusion in statistical analysis: 27 patients in the MUS alone group and 24 in the concomitant apical repair group. The average ultrasound measurement for the urethral length was similar between groups (27.4 mm vs 27.25 mm, p=0.728). The MUS position was measured as a proportion of the urethral length and was similar in both groups (0.24 vs 0.26; p=0.71). There was also no difference in the angle between the sling and the symphysis pubis (24 vs 23 degrees, p=0.574). While both groups demonstrated a significant improvement in the UDI-6 scores, the change was not significantly different between the groups; with 3.7% in the MUS alone group and 4.2% in the concurrent apical repair group reporting persistent SUI postoperatively (p=1.0). There was not a significant difference in post-operative complication rates.

Conclusions: There have been conflicting reports of MUS success when placed on its own versus at the time of prolapse repair. One hypothesis has been proposed that positioning of the MUS may be different at the time of the prolapse repair. In our study we did not observe any difference in the MUS positioning along the urethra, urethral length and the sling angle when placed with or without a concurrent prolapse repair. This study also establishes a method of utilizing translabial ultrasound intraoperatively to further evaluate differences in anatomy during live MUS surgery.