Comparison of levator ani muscle defects and function in women with and without pelvic organ prolapse

To compare levator ani defects and pelvic floor function among women with prolapse and controls. Levator ani structure and function were measured in a case-control study with group matching for age, race, and hysterectomy status among 151 women with prolapse (cases) and 135 controls with normal support (controls) determined by pelvic organ prolapse quantification examination. Magnetic resonance imaging was used to determine whether there were "major" (more than half missing), "minor" (less than half of the muscle missing), or no defects in the levator ani muscles. Vaginal closure force at rest and during maximal pelvic muscle contraction was measured with an instrumented vaginal speculum. Cases were more likely to have major levator ani defects than controls (55% compared with 16%), with an adjusted odds ratio of 7.3 (95% confidence interval 3.9-13.6, P