Aims: To evaluate differences in the curvature of the urethral-vaginal interface in women with and without stress urinary incontinence (SUI) using geometric morphometric analysis techniques.
Methods: We conducted a pilot case-control study using magnetic resonance imaging (MRI) scans of 18 women with and without SUI. The urethral-vaginal interface at the level of the mid-urethra was fitted with a second-order polynomial regression. The chord length and chord-to-vertex length of the resulting parabolic curve were used to calculate the arc length and radius of a circular arc fitted to the interface curvature. Demographic characteristics and Pelvic Organ Prolapse Quantification (POP-Q) parameters were collected. Subjects were stratified by those with and without SUI, as well as by those with and without anterior wall prolapse beyond 2 cm proximal to the hymen (Aa > -2 cm).
Results: The radius of the urethral-vaginal interface curvature was not found to be different between subjects with and without SUI (8.8 vs. 9.2 mm, p = 0.53); however, this value was smaller in subjects with Aa > -2 (8.4 vs. 11.9 mm, p = 0.03). The chord length, chord-to-vertex length, and arc length comprising the urethral-vaginal interface curvature were similar between subjects with and without SUI, and between subjects with and without Aa > -2 cm (p > 0.05 for all).
Conclusions: In this pilot study population, the radius of the urethral-vaginal interface curvature at the mid-urethra was smaller among women with anterior vaginal wall prolapse beyond 2 cm proximal to the hymen. A difference in the urethral-vaginal interface curvature among women with and without SUI was not found.
Keywords: MRI; geometric morphometric analysis; pelvic support; stress urinary incontinence; urethral support.
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