Electromyographic assessment of women's pelvic floor: What is the best place for a superficial sensor?

AIMS: To compare the electromyographic signal of different surface electrodes and to identify the channel that presents the highest level of electromyographic activity through the mean and peak of Root Mean Square (RMS).

METHODS: Thirty healthy women participated in this study. Each woman completed three collections (on different days) of electromyographic data. Three maximal voluntary contractions of the pelvic floor muscles were requested. The electromyographic signal was recorded by intravaginal probe and surface electrodes placed on the perianal region and on the region immediately below the labia majora. To analyze the signal, an epoch of 500 ms was selected during the second contraction. The Kruskal-Wallis test followed by a post hoc Mann-Whitney test was used to compare means and to identify differences. The Bland-Altman method was used to verify the agreement between the measurements. A significance level of P ≤ 0.05 was adopted.

RESULTS: There was agreement only between the measurements from perianal electrodes and intravaginal probe. Furthermore, there was no difference between the perianal electrodes and intravaginal probe in RMS mean (P = 0.225) and RMS peak (P = 0.315). However, these electrodes locations presented greater values than the electrodes in the region immediately below the labia majora (RMS mean: P < 0.001; P = 0.016. RMS peak: P < 0.001; P = 0.02).

CONCLUSIONS: The intravaginal probe and the surface electrodes in perianal region are equivalent for healthy nulliparous women. The choice must be done according to the values and preferences of the patient.