High-resolution endovaginal MR imaging in stress urinary incontinence

Abstract

The causes of stress urinary incontinence are not completely known. Recent papers have stressed the importance of more anatomical information, which may help to elucidate the mechanism of stress urinary incontinence. The purpose of this study was to evaluate the prevalence of lesions of the urethral support mechanism and lesions (defects and scars, thinning) of levator ani muscle with endovaginal MRI in a case-control study. Forty women (median age 52 years, age range 40-65 years)--20 patients with stress urinary incontinence (cases) and 20 age-matched healthy volunteers (controls)--underwent endovaginal MRI: axial, coronal, and sagittal T2-weighted turbo spin echo. The examinations were evaluated for the presence of lesions of urethral supporting structures and levator ani and scar tissue of the levator ani. The thickness of the levator ani muscle was measured. Lesions of the urethral support system and levator ani were significantly more prevalent in cases than in controls ( p<0.01). Median levator ani thickness in patients was significantly lower than in healthy controls [2.5 mm (range 0.9-4.1 mm) vs 3.9 mm (range 1.4-7 mm)] ( p<0.01). This study indicates a relationship between stress urine incontinence and the presence of lesions of the urethral support and levator ani and levator ani thinning.

Role of Puborectalis Muscle in the Genesis of Urethral Pressure

“…Studies show that women with stress urinary incontinence often have weak or asymmetrical contraction of the pelvic floor. 3,4 Using electromyography Kenton and Brubaker noted that the pelvic floor muscles and RHB sphincter make independent contributions to urinary continence and work together to facilitate urethral closure by a reflex muscle contraction. 30 We propose that the PRM, a component of the pelvic floor muscles, has a direct role in the genesis of UP during reflex contractions of the abdominal wall and pelvic floor muscles, the latter of which are associated with increases in intra-abdominal pressure (stress maneuvers).…”

“…Clinical studies demonstrated that women with stress urinary incontinence often have weak or asymmetrical contractility of the pelvic floor muscles, 3,4 which implies that the latter has a role in urinary continence. Studies show that voluntary pelvic floor muscle contractions have a significant impact on UP.…”

Magnetic resonance imaging in assessment of stress urinary incontinence in women: Parameters differentiating urethral hypermobility and intrinsic sphincter deficiency

“…MRI findings related to SUI caused by UH and ISD in women have been descri bed [9] . Previous studies of MRI in female patients with SUI were focused on the assessment of lesions of the urethral support mechanism [10] , defects of the levator ani muscle [11,12] , and paravaginal fascia [13] , as well as on the kinematics of pelvic floor muscles function [14] . To date, however, the role of MRI in the specific diagnosis of SUI caused by UH and/or ISD has not been documented.…”

“…UH was diagnosed if the angle changed over 30 degrees between the rest and strain (as per definition of hypermobility) [11] . The bladder neck descent was measured as a distance (cm) between its position at rest and strain in reference to the pubococcygeal line (PCL, a line drawn from the inferior margin of the pubic bone to the last coccygeal joint).…”

MRI of pelvic organ prolapse

“…The angle of the urethral axis is abnormal when it is greater than 30 degrees from the vertical [7]. Urethral hypermobility is seen in patients with symptoms of stress urinary incontinence and abnormalities of the urethral support ligaments and levator ani muscle are seen on high-resolution imaging [18]. These include defects in the levator muscle and scar tissue.…”