It is estimated that 30% of women are unable to perform a voluntary pelvic floor muscle (PFM) contraction [1]. Many women, even after careful instruction about the anatomy and function of the PFM will not be able to distinguish the contraction of the PFM from the contractions of other muscles, such as the rectus abdominis, gluteus maximus and hip adductors. Deficiencies in PFM function has been associated with pelvic organ prolapse (POP), urinary incontinence (UI) fecal incontinence (FI), and sexual dysfunctions. PFM training is considered first-line treatment for UI in women. However, for those not able to contract, this treatment is unavailable. The primary aim of this study was to assess the efficacy of intravaginal electrical stimulation (iES), to provide a voluntary PFM contraction in women unable to contract. The secondary aim was to assess the effect of this intervention on UI reports.

This is an assessor blinded randomized controlled trial. Women over 18 years of age, routinely referred to a tertiary care, with PFM dysfunctions were recruited. Exclusion criteria were neurological diseases; symptoms of vaginal or urinary tract infection; pelvic organ prolapses > stage 2; suspected or confirmed pregnancy and cognitive impairments. In the first session, demographic data were collected, and a standardized PFMs assessment using vaginal palpation was performed by a women´s health physiotherapist. Only participants with PFM function grade 0 or 1 assessed by bi-digital palpation on the Modified Oxford Scale (MOS) were included. Eligible participants were randomized to either the intervention group (IG) to receive iES or to the control group (CG) with no intervention. The randomization procedure was conducted using computer-generated random numbers. The primary outcome measure was PFM strength, evaluated through vaginal palpation using the Modified Oxford Scale (MOS) and the secondary outcome, was UI assessed by the International Consultation on Incontinence Questionnaire on Urinary Incontinence – Short Form (ICIQ-UI-SF). All participants were assessed at baseline and after 8 weeks. The intervention was performed once a week using the device Dualpex Quark®. A biphasic current was used and the stimulation parameters were:  50 Hz frequency, pulse width of 200 microseconds, contraction time (Time on) of 5 seconds, relaxation time (Time off) of 10 seconds, current intensity set according to the participants sensitivity (tolerance), and total stimulation time of 20 minutes [2]. In the last 10 minutes of the intervention, voluntary PFM contractions were requested along with the involuntary contractions caused by the stimulator. The same examiner performed all the assessments and was blind to the allocation of the groups, not being involved with the intervention. The intervention sessions were conducted by a single physical therapist who had 20 years of experience in women's health physical therapy and who had no contact with the assessor. The adherence to the intervention was recorded at the time of the physiotherapy session and was registered by the researcher who applied the intervention. Data analysis was also done without knowing which group the participant was allocated to. Data were first tested for normality. For comparison between groups, continuous variables were tested using t-test, for variables with normal distribution Anderson-Darling test was used, and for the remaining variables non-parametric test (Mann-Whitney e Brunner-Munzel) were used. For categorical variables Fisher test was used. Primary outcome was analyzed using logistic regression and for the secondary outcome mixed regression model. The level of significance adopted was 0.05 using the software R 3.6.0. Sample size calculation was based on a pilot sample considering the capacity for voluntary contraction of the PFM assessed using the MOS. It was considered that the participants who had a score greater than or equal to 2 according to the MOS acquired the ability to contract their PFM. Then, the proportions between each group were compared. The sample size was based on the test of differences between proportions and Fisher's exact test. Adopting a significance level of 5% and a test power of 90%, the need to obtain 14 participants per group was estimated. Considering possible sample losses, a minimum of 20 women in each should be included in the study.

A total of 172 women were recruited, of those, 40 did not agree to participate and 29 did not attend the first assessment. One hundred and three women were screened for eligibility, of whom 39 did not meet the inclusion criteria (34 scored 2 or more in the MOS and 6 had some neurological impairment). Sixty-four women were randomized, 31 to the IG and 33 to the CG. Demographic data are presented in Table 1. Sixty-one women provided data that could be included in the regression analysis (IG n=28 and CG n=33). There were 3 losses to follow up. After the intervention, the ability to contract the PFM was acquired by 35.7% of the participants in the IG vs 12.1% of the participants in the CG. Table 2 shows that the IG had 4.03 higher odds of being able to voluntarily contract PFM in comparison with the CG. At baseline the mean ICIQ score on the IG was 16.29 (SD±3.17; 95%CI 15.23 – 17.52) and on the CG 14.24 (SD±3.69; 95%CI 12.93 – 15.55) (p=0.029) and after the intervention on IG was 13.54 (SD±5.32; 95%CI 11.54 – 15.64) and on CG was 13.45 (SD±4.69; 95%CI 11.97 – 15.00) (p=0.73). The ICIQ-UI-SF total scores showed statistically significant difference between groups (p=0.036), but no difference between the time (p=0.25) and its interaction group:time (p=0.051) (Table 2). At baseline 100% of participants reported UI on both groups and after the intervention 92.86% on the IG and 96.97% on the CG (p=0.47) Adherence to the intervention was high, 20 participants completed 8/8 sessions, 3 completed 7/8, 3 completed 6/8,1 did 3/8 sessions and 1 did 1/8 session.

The results of the present study suggest that the use of intravaginal electrical stimulation, together with attempts of simultaneous voluntary PFM contractions with the stimulation can facilitate ability to voluntarily contract the PFM. To our knowledge this is the first RCT showing that women can learn to contract the PFM via attempts to contract during electrical stimulation. However, the protocol with only one training session per week did not reduce the ICIQ-UI-SF sum score [3]. This approach can be considered for women who are unable to contract their PFM prior to engage in a PFM training program.

Intravaginal electrical stimulation can be considered to be used to teach women unable to contract the PFM. However, it was not effective in reducing the severity of UI.

Talasz H, Himmer-Perschak G, Marth E, Fischer-Colbrie J,Hoefner E, Lechleitner M. Evaluation of pelvic floor musclefunction in a random group of adult women in Austria. IntUrogynecol J Pelvic Floor Dysfunct. 2008;19(1):131---135.
Mateus-Vasconcelos ECL, Brito LGO, Driusso P, Silva TD, Antonio FI, Ferreira CHJ. Effects of three interventions in facilitating voluntary pelvic floor muscle contraction in women: a randomized controlled trial. Braz J Phys Ther. 2018 Sep - Oct;22(5):391–399.
Dumoulin C, Cacciari LP, Hay-Smith JC. Pelvic floor muscle training versus no treatment, or inactive control treatments, for urinary incontinence in women. Cochrane database Syst Rev, 10 (10), CD005654, 2018 Oct 4.