New imaging method for assessing pelvic floor biomechanics.

OBJECTIVES The investigation of female pelvic floor biomechanics is attracting attention due to its importance in pelvic floor dysfunction and childbirth. To date, there are no established means of assessing pelvic floor elasticity. We propose the use of translabial ultrasound to estimate strain, one element of pubovisceral muscle elasticity. METHODS Ultrasound datasets of 98 women seen at a tertiary urogynecology clinic were reviewed using proprietary software. Data were processed to estimate muscle fiber strain during Valsalva and contraction by measuring hiatal circumference and deducting bony arc length. Clinical assessment included levator palpation during maximal contraction (modified Oxford grading scale) and at rest, with tone recorded on a new six-point scale. Analysis of imaging data was performed without knowledge of clinical data. RESULTS Mean age was 52.2 (range, 19-87) years and mean parity was 2.4 (range, 0-8). Mean (SD) hiatal area during contraction, rest and Valsalva was 15.4 (3.8) cm(2), 18.9 (5.0) cm(2) and 27.3 (8.9) cm(2), respectively. There was a moderate association between strain during contraction and Oxford grade (r = 0.439, P < 0.0001), and a weak but significant association between strain during Valsalva and resting tone (r = - 0.224, P = 0.033). CONCLUSIONS Translabial ultrasound can be used to measure strain, a component of pubovisceral muscle elasticity, and we have validated the technique against clinical assessment. Pubovisceral strain during contraction correlates positively with Oxford grade. Pubovisceral strain during Valsalva correlates negatively with resting tone grade. This new non-invasive ultrasound technique may be of value for assessing patients with pelvic floor dysfunction.