Is it necessary to diagnose levator avulsion on pelvic floor muscle contraction?

Avulsion of the levator ani muscle commonly occurs at vaginal birth. This condition is usually diagnosed by translabial ultrasound (TLUS) during pelvic floor muscle contraction (PFMC). Some patients are unable to achieve a satisfactory PFMC and in these cases avulsion is assessed at rest. The aim of this study was to validate the diagnosis of levator avulsion by means of TLUS at rest.

This was a retrospective study of 233 women seen at a tertiary urogynecological center. All women underwent four-dimensional TLUS in the supine position and after voiding. Volumes were obtained on maximal PFMC and at rest. Analysis of the volumes was performed with the observer blinded against all clinical data. Avulsion was defined as an abnormal levator ani muscle insertion that was visible in at least three consecutive axial plane slices, at and above the level of minimal hiatal dimensions, at 2.5-mm intervals. We examined the correlation between both assessment methods using Cohen's kappa coefficient and tested the association of each method with female pelvic organ prolapse on clinical examination, organ descent on ultrasound and hiatal ballooning.

In total, datasets from 202 women were available for analysis. The correlation between a diagnosis of avulsion in volumes obtained at rest and those on PFMC was moderate, with a kappa value of 0.583 (95% CI, 0.484-0.683). Agreement for defects visualized on single slices was moderate, with a kappa value of 0.556 (95% CI, 0.520-0.591). When avulsion diagnoses at rest and on PFMC were tested against symptoms of prolapse, and prolapse on clinical examination and on ultrasound, neither of the two methods was superior.

Although tomographic ultrasound imaging during PFMC enhances tissue discrimination, this may not translate to superior diagnostic performance. Hence, volumes obtained at rest may be used in women unable to contract their pelvic floor. The diagnosis of levator avulsion by tomographic pelvic floor ultrasound is equally valid when performed at rest or on PFMC. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.