The Reliability of the Rehabilitative Ultrasound Imaging Method for Assessing Pelvic Floor Muscles Function in Pregnant Women

Background: To our knowledge, there is scant research on the use of rehabilitative ultrasound imaging (RUSI) method for evaluating bladder base displacement in pregnant women. The RUSI is a non-invasive and simple method that assesses the function of pelvic floor muscles (PFM) based on the movement of the bladder base. Objectives: This study aims to assess the reliability of the RUSI for the assessment of PFM function in pregnant women during voluntary muscle contractions. Materials & Methods: In this cross-sectional study, ۱۸ pregnant women with different gestational ages participated. The amount of bladder base displacement during PFM contraction was assessed in all women and considered an indicator of PFM function. The test re-test reliability was evaluated using the intraclass correlation coefficient (ICC) and Bland-Altman plot. The percentages of standard error of measurement (SEM%) and minimal detectable change (MDC%) were also calculated. Results: The mean amount of bladder base displacement during PFM contraction at time points ۱ and ۲ was ۴.۸۹±۱.۴۳ and ۴.۸۱±۱.۴۱, respectively. The ICC was ۰.۹۸۹ (۹۵% CI, ۰.۹۶۹%, ۰.۹۹۶%), which indicates excellent reliability. The Bland-Altman plot showed that all the points were within the ۹۵% limits of agreement with no considerable trend or bias. The SEM% and MDC% were ۳.۰۹% and ۸.۴۱%, respectively. Conclusion: The intra-rater reliability of the RUSI to assess PFM function in pregnant women is high, and can be useful for further studies on the PFMs in pregnant women.