Study design, materials and methods
This is an observational cross-sectional study approved by the Ethics Committee of the institution. The study was conducted from August 2016 to April 2018 at a basic health unit in Brazil.
The study included Brazilian women, living in X city, over 18 years of age and literate. Participants reporting any discomfort and/or intolerance to vaginal palpation were excluded. The women were recruited throughout the city with the dissemination of the research on the internet, on the radio of the University and in a healthcare unit. Women who met the inclusion criteria and agreeing to participate signed the Informed Consent Term and were included in the study. A questionnaire including questions on sociodemographic, obstetric and anthropometric information was answered by all participants. Women who answered that they were able to sign their name and read it, were considered literate. Being physically active was defined as performing any type of physical activity at least three times a week for 30 minutes. The participants were evaluated only once. Two experienced women's health physiotherapists collected data according to the following sequence: researcher 1 performed the vaginal palpation and researcher 2 after vaginal palpation assessed the women's self-perception of their PFM function. First researcher 1 assessed PFM function by the modified Oxford scale (MOS) through vaginal palpation. The MOS evaluates PFM contraction as follows: 0 = no contraction; 1 = very weak contraction; 2 = weak contraction; 3 = moderate contraction; 4 = good contraction; and 5 = strong contraction. Prior to the vaginal palpation, the researcher 1 gave individual instructions to participants about the pelvic floor and how to contract the muscles. The explanation for the contraction was described as the closure of the vaginal opening, associated with an inward perineal movement. After the instructions, the same researcher positioned the woman in a supine position with the knees and hips flexed and abducted, and the feet supported on the table. During the evaluation, the participants were asked to perform a maximum voluntary contraction of the PFM and to relax as soon as they felt they had achieved it. They were instructed to perform three contractions but only the last one was registered. The researcher classified the contraction according to the MOS. The participants were instructed to memorize her performance related to the last PFM contraction. After completion of the vaginal assessment researcher 1 left the room, and researcher 2, who was blinded to the participants' ability to contract, assessed their self-perceived PFM function using the MOS. The participants were explained and shown the MOS classification and then rated how they perceived their own PFM contraction. Report of UI was assessed using the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-UI-SF).
The sample size calculation was performed with a pilot sample of 20 women using a linear regression in the Gpower program. Based on the clinical evaluation of PFM contraction (vaginal palpation) and self-perception, using adjustment of values with variable age, critical T of 1.67, residual standard deviation of 0.920, correlation of 0.310 and statistical power of 90%, the estimated sample size was 82 participants. Statistical analysis was performed using the statistical software SPSS 22. The descriptive analysis ispresented as means and standard deviations or as relative and absolute frequencies.
Agreement between self-perception and the examiner's evaluation of the PFM contraction was assessed with Weighted Kappa concordance correlation coefficient was used. Spearman's correlation coefficient was used to correlate the ICIQ-UI-SF with the self-perception of PFM contraction. To test the association between UI reports and the self-perception of PFM contraction the Fisher's exact test was used. The values of p≤0.05 were considered statistically significant.
A total of 163 women were recruited, 82 were assessed and 81 did not attend the evaluation session. The sample had a mean age of 46.8 years and was mostly self declared white, married, with 8 to 11 years of formal education and engaged in a remunerated work. Participants had a mean of 2.2 gestations, most of them were not physically active, were of reproductive age, had no UI complaints, and had never e done PFM training.
Most of women had a score of 3 according to the examiner´s evaluation, followed by 4 and 2. The self-perception of women, using the same scale, showed a predominance of score 4, followed by 3 and 5.
The agreement between the assessed PFM and self-perceived PFM function was Kw = 0.139 (p = 0.08). Self-perception of PFM contraction did not correlate significantly with ICIQ-UI-SF (rs: 0.011, p= 0.92). A moderate negative correlation was found between the assessed PFM contraction and ICIQ-UI-SF (rs: -0.406, p: 0.00). The association between UI complaint and the exact agreement of self-perception with PFM contraction was 0.767 (p = 0.64).
Women with a score of 3 to 5 (MOS) and who were considered able to perform a correct PFM contraction, have a better self-perception than women who were palpated to have a score of 0 to 2 Women unable to contract the PFM overestimated their ability to perform the contraction.
Interpretation of results
The studied population of the present study was heterogeneous in terms of age, educationa level, parity and in general showed a low self-perception of PFM contraction. Two thirds of the participants did not perceive their PFM contraction correctly. Women with a better PFM function assessed by the examiner had a better perception of their PFM function. No statistically significant correlation was found between self-perception of PFM contraction and ICIQ-UI-SF.
The observed difference between self-perceived and assessed contraction could be explained from a motor task point of view, which consider the generation of signs of central origin and / or peripheral sensory receptors. Two studies with other muscle groups showed that sensory perceptions of force may present a distinct response depending on the motor command and afferent signals. The force generated with the presence of an external stimulus is greater when compared to a force originated without this stimulus. This may occur because the external stimulus could be functioning as a sensory feedback which allows us to direct attention to one specific body site, partially suppressing the afferent activity of other body movements. This theory is partially consubstantiated by an RCT showing that vaginal palpation was more effective than verbal instruction to facilitate a pelvic floor muscle contraction in women with non-contracting PFM. The evaluation of self-perceived PFM function in the present study did not occur at the same time when the women received the external stimulus (vaginal palpation) and future studies should compare women´s self perception during and after vaginal palpation.