Levator Plate Upward Lift on Dynamic Sonography and Levator Muscle Strength

To compare digital palpation with levator plate lift measured by endovaginal and transperineal dynamic sonography.

Dynamic transperineal and endovaginal sonographic examinations were performed as part of multicompartmental pelvic floor functional assessment. Patients were instructed to perform Kegel contractions while a probe captured a video clip of levator plate movement at rest and during contraction in a 2-dimensional midsagittal posterior view. We measured the distance between the levator plate and the probe on endovaginal sonography as well as the distance between the levator plate and the gothic arch of the pubis on transperineal sonography. The change in diameter (lift) and levator plate lift ratio (lift/rest × 100) were calculated. Pelvic floor muscle strength was assessed by digital palpation and divided into functional and nonfunctional groups according to the Modified Oxford Scale. Mean differences in levator plate upward lift were compared by Modified Oxford Scale scores using Student t tests and analysis of variance.

Seventy-four women were available for analysis. The mean age was 55 (SD, 11.9) years. When measured by vaginal dynamic sonography, mean lift and lift/rest ratio values increased with increasing Modified Oxford Scale score (analysis of variance, P= .09 and .04, respectively). When scores were categorized to represent nonfunctional (0-1) and functional (2-5) muscle strength groups, the mean lift (3.2 versus 4.6 mm; P = .03) and lift/rest ratio (13% versus 20%; P = .01) values were significantly higher in women with functional muscle strength. All patients with lift of 30% or greater detected by vaginal sonography had functional muscle strength.

A greater levator plate lift ratio detected by dynamic endovaginal sonography was associated with higher muscle strength as determined by the Modified Oxford Scale. This novel measurement can be incorporated into sonographic evaluation of levator ani function.