Abstract
INTRODUCTION AND HYPOTHESIS: The integrity of the perineal body (PB) is essential for pelvic floor function. Anatomical deviations in the PB anatomy after childbirth can lead to pelvic floor symptoms, but the reliability of ultrasound assessments for these deviations is unclear. This study evaluates the intra- and inter-rater reliability of detecting deviations in the muscles fusing into the PB and measuring its size using three-dimensional endovaginal (3D EVUS) and endoanal ultrasound (3D EAUS) 1 year postpartum. METHODS: Forty primiparous women underwent 3D EVUS and 3D EAUS 1 year after birth. The transverse perineal, puboperinealis, and puboanalis muscles were identified where they fuse into the PB. Deviations were defined as discontinuities in or absence of muscle fibers on the right, left, or center. Measurements of PB height, length, and area were taken in the mid-sagittal plane. Intra- and inter-rater reliability for muscle deviations were assessed using percentage agreement and Cohen's kappa, while PB size measurements were evaluated using the intra-class correlation coefficient. RESULTS: Kappa values indicated excellent intra- and inter-rater reliability for the transverse perineal muscle (κ = 0.881, κ = 0.871) and puboperinealis muscle (κ = 0.849, κ = 0.810) in 3D EVUS. For the puboanalis muscle, intra-rater reliability was excellent (κ = 1.00) and inter-rater reliability was good (κ = 0.658). Similar kappa values were found using 3D EAUS. Percentage agreement for deviations ranged from 90% to 100% for both ultrasound methods. PB measurement also showed good to excellent reliability: 0.76-0.97 for 3D EVUS and 0.90-0.99 for 3D EAUS. CONCLUSION: 3D EVUS and 3D EAUS are reliable methods for assessing PB muscle deviations and its size 1 year postpartum.