Pelvic floor ultrasound imaging: are physiotherapists interchangeable in the assessment of levator hiatal biometry?

Abstract

Purpose: To evaluate inter-examiner reliability in the ultrasound (US) assessment of levator hiatal dimensions when different physiotherapists perform independent data acquisition and analysis.

Methods: In this cross-sectional observational study, 14 asymptomatic nulliparous women were imaged at rest, during pelvic floor muscle contraction, and during Valsalva manoeuvre by two physiotherapists using three-dimensional (3D) and four-dimensional (4D) transperineal US. Examiners each measured the dimensions of the levator hiatus (area and antero-posterior and transverse diameters) from the US volumes they respectively acquired. Inter-examiner reliability was determined using intra-class correlation coefficients (ICCs), and inter-examiner agreement was determined using Bland-Altman analyses.

Results: The ICC results demonstrated very good inter-examiner reliability (ICC=0.84-0.98); Bland-Altman results showed high inter-examiner agreement across all measurements.

Conclusions: Trained examiners may be considered interchangeable in the US assessment of levator hiatal biometry. Overall, trained physiotherapists using transperineal US imaging to assess levator hiatal biometry can be confident when comparing their own clinical findings to those of their colleagues and to findings published in the literature.

Keywords: pelvic floor; reproducibility of results; three-dimensional imaging; ultrasonography.

Figures

Figure 1

(i) Mid-sagittal plane image. The plane of minimal antero-posterior (AP) diameter is indicated by the dashed line joining the posterior-inferior aspect of the symphysis (SP) and the inner border of the levator ani muscle at the anorectal junction. (ii) Axial plane image. U urethra, V vagina, A anus. (iii) Measurements in the axial plane of minimal AP diameter. AP diameter of the levator hiatus (LH) (dashed line), transverse diameter of the LH (dotted line), area of the LH (area bordered by the solid tracing).

Figure 2

Mid-sagittal plane image and axial plane image in the plane of minimal antero-posterior diameter taken (i) at rest, (ii) on maximal pelvic floor muscle contraction, (iii) on maximal Valsalva.