An intra- and interrater reliability and agreement study of vaginal resting pressure, pelvic floor muscle strength, and muscular endurance using a manometer

Abstract

Introduction and hypothesis Manometry is commonly used to assess pelvic floor muscle (PFM) function. Aims of the study were to assess intra- and interrater reliability and agreement of vaginal resting pressure, PFM strength, and muscular endurance using a high-precision pressure transducer.

Methods A convenient sample of 23 women was included. The participants were tested twice by two examiners on day 1 and retested after 1 week by one examiner. Vaginal resting pressure, PFM strength, and muscular endurance were measured by manometer (Camtech AS). Intraclass correlation coefficient (ICC) and Bland–Altman plots were used to analyze reliability and agreement respectively. Results are presented with mean differences (bias) and minimal detectable change.

Results Twenty participants completed the tests (mean age 55.8 years [27–71], mean parity 1.7 [range 0–3], and mean body mass index 23.7 [range 18.4–27.2, SD 2.4]). ICC values were very good (ICC >0.90) for all measurements. Considerable intervariation of scores, and outliers were seen for measurements representing the highest values. Agreement with mean differences (bias) and minimal detectable change for the intrarater assessment was for vaginal resting pressure: −2.44 ± 8.7 cmH2O, for PFM strength −0.22 ± 7.6 cmH2O, and for muscular endurance 0.75 ± 59.5 cmH2O/s. The interrater agreement for vaginal resting pressure was: 1.36 ± 9.0 cmH2O, for PFM strength 2.24 ± 9.0 cmH2O, and for muscular endurance 15.89 ± 69.7 cmH2O/s.

Conclusions Manometry (Camtech AS) seems less accurate for the strongest women. In clinical practice, significant improvement in PFM variables needs to exceed the minimal detectable change to be above the error of measurement.