(030) Reliability of Shear Wave Elastography for the Assessment of Pelvic Floor Muscle Stiffness
Authors: Starzec-proserpio M , Roch M , Gaudreault N , Daigle F , Bureau N , Morin M 
Published: May 2023

Abstract

Introduction
Shear wave elastography (SWE) has gained popularity for assessing skeletal muscle stiffness and could potentially overcome some limitations associated with the assessment of the pelvic floor muscles (PFMs). Additionally, SWE is a non-invasive and painless alternative to the current method of assessing the PFMs, which is often painful or even impossible to perform in women with sexual pain. Before implementing this promising method, it is of the utmost importance to assess its reliability. Available data are limited and currently, there is no study investigating the reliability of SWE for the assessment of the different PFMs.

Objective
To investigate the intra-rater and inter-rater reliability of SWE in measuring the stiffness of the different PFMs at rest and during maximal voluntary contraction in asymptomatic women.

Methods
Thirty asymptomatic nulliparous women participated in the study. They each attended a single assessment session conducted by two independent assessors. SWE assessments were performed using the Aixplorer device (Supersonic Imaging) equipped with linear probes. Four PFMs (i.e., bulbospongiosus, ischiocavernosus, transverse perineal, puborectalis) and the perineal body were assessed at rest and during maximal voluntary contraction. Measurements were taken twice by the first assessor (intra-rater reliability) and once by the second assessor (inter-rater reliability). SWE data were saved and analyzed offline. For both the resting and contraction states, three consecutive frames with stable SWE maps were selected. The average shear modulus was evaluated by manually defining a region of interest that corresponded to the structure assessed. To determine intra- and inter-rater reliability, intraclass correlation coefficients (ICC) were calculated.

Results
Intra-rater reliability was excellent for the ischiocavernosus and puborectalis at rest and during contraction as well as for the transverse perineal and perineal body during contraction (ICC 0.82-0.95); good for the bulbospongiosus during contraction as well as the transverse perineal and perineal body at rest (ICC 0.61-0.79); and fair for the bulbospongiosus at rest (ICC 0.51). For the inter-rater reliability, the results were as follows: excellent for the transverse perineal and puborectalis during contraction (ICC 0.84-0.89); good for the puborectalis and transverse at rest as well as the perineal body during contraction (ICC 0.62-0.72); fair for the perineal body at rest (ICC 0.48); and poor for the bulbospongiosus and ischiocavernosus muscles (ICC 0.22-0.38) in both states.

Conclusions
These findings support the intra- and inter-rater reliability of SWE for the assessment of PFM stiffness in women, especially in the puborectalis muscle, transverse perineal muscle, and perineal body. By enabling the assessment of localized areas of stiffness in the different PFMs, SWE may be a stepping stone in enhancing our understanding of the role of the PFMs in the pathophysiology and treatment of sexual pain. Further studies investigating PFM stiffness with the use of SWE assessment are encouraged.

Disclosure
No