The quantification of levator muscle resting tone by digital assessment.

The biomechanical properties of the puborectalis muscle are likely to be important for pelvic organ support. However, neither elasticity nor its clinical correlate, muscle resting tone, have received much attention to date. We therefore conducted a prospective study to test a newly developed resting tone scale for validity and reproducibility. Ninety-eight patients underwent a physical examination including prolapse staging and palpation of the levator ani. They were also assessed by 4D translabial ultrasound for levator hiatal dimensions and prolapse assessment. Resting tone was negatively associated with anterior and posterior compartment prolapse. An independent test-retest series yielded a weighted kappa of 0.55 (CI 0.44-0.66), implying "moderate" repeatability. Resting tone of the puborectalis muscle can be determined by digital palpation. It is moderately repeatable and associated with pelvic organ prolapse. Palpation of resting tone may be a useful new tool for assessing women with pelvic floor dysfunction.