Levator avulsion and grading of pelvic floor muscle strength.

In a retrospective study investigating the relationship between levator avulsion and clinical grading of levator ani muscle strength, we analyzed the 3D/4D translabial ultrasound and digital assessment data of 1,112 women seen in a tertiary Urogynecological clinic. Levator avulsion was diagnosed whenever the examiner was unable to palpate the insertion of the pubovisceral muscle on the inferior pubic ramus and/or whenever a discontinuity between bone and muscle was detected on ultrasound. For clinical grading of levator muscle strength, we used the modified Oxford grading. Avulsion defects were found in 252 women (23%), and this was associated with a highly significant reduction in the overall Oxford grading (2.07 vs 2.81, P < 0.001). The prevalence of avulsion increased depending on the side differences in the modified Oxford grading: from 16% when there was no difference to 76% when the side difference was 1.5 or higher (P < 0.001). Avulsion of the puborectalis muscle seems to have a marked effect on pelvic floor muscle strength, which may help in diagnosing trauma.