The urethra and its supporting structures in women with stress urinary incontinence: MR imaging using an endovaginal coil

OBJECTIVE. The objective of this study was to evaluate the urethra and its supporting structures in patients with stress urinary incontinence using MR imaging with an endovaginal coil. SUBJECTS AND METHODS. We reviewed MR images obtained using an endovaginal coil in 63 patients with stress urinary incontinence and in 16 continent women. We compared the two groups for the thickness of the striated muscle, smooth muscle, and mucosa-submucosa of the urethra; degree of asymmetry of the puborectalis muscle; frequency of distortion in the periurethral, paraurethral, and pubourediral ligaments; degree of the vesicourethral angle; and dimension of the retropubic space. Using the status of the urethra and its supporting structures as our basis, we scored the risk of stress urinary incontinence for each woman on a scale of 0-5. RESULTS. The striated muscle layer of the urethra was thinner in the group with stress urinary incontinence (mean +/- SD, 1.9 +/- 0.5 mm) than that in the continent group (2.6 +/- 0.4 mm) (p < 0.001). A high degree of asymmetry of puborectalis muscle (> 1.5) was more frequent in the group with stress urinary incontinence (29%) than in the continent group (0%) (p = 0.015). Supporting ligaments were more frequently distorted in the incontinent group than in the continent group. Distorted periurethral ligaments were found in 56% of the patients with stress urinary incontinence versus 13% of the women who were continent; distorted paraurethral ligaments were found in 83% of the patients with stress urinary incontinence versus 19% of the women who were continent; and distorted pubourethral ligaments were found in 54% of the patients with stress urinary incontinence versus 19% of the women who were continent (p < 0.05). The group with stress urinary incontinence had a greater vesicourethral angle (148degrees vs 125degrees) and larger retropubic space (7.5 vs 5.1 mm) than did the women who were continent (p < 0.05). The score for the risk of stress urinary incontinence was higher in the group with stress urinary incontinence (3.3 +/- 1.4) than in the women who were continent (1.0 +/- 1.2) (p < 0.001). CONCLUSION. MR imaging with an endovaginal coil revealed significant morphologic alterations of the urethra and supporting structures in patients with stress urinary incontinence.