Comparison of a novel pen-like electrode and standard patch electrodes for perineal muscle stimulation in women: a pilot study

<i>Objective</i>. Intracavitary electrical stimulation is widely used in the treatment of urinary incontinence. However, it is contraindicated for a subset of patients, for whom current external electrode alternatives offer limited adaptability and therapeutic flexibility. This study compared the performance of a mobile, pen-like electrode with fixed external patch electrodes for pelvic floor muscle electrical stimulation in asymptomatic volunteers. The proposed electrode enables sequential stimulation of motor points and visual monitoring of muscle contraction, aiming to overcome limitations associated with intracavitary and fixed patch approaches.<i>Methods</i>. A parallel-group study (1:1) was conducted with 28 asymptomatic participants without diagnosed pelvic floor dysfunction (mean age: 25.4 ± 4.1 years; BMI: 22.8 ± 2.5 kg m^-2). Participants were randomly allocated to Group A (pen-like electrode, n = 14) or Group B (fixed patch electrodes, n = 14). Both groups underwent 12 sessions of neuromuscular electrical stimulation (NMES) using identical stimulation parameters. The primary outcome was the change in maximum vaginal pressure, measured by perineometry, after 12 sessions. Statistical analyses included paired t-tests for intra-group comparisons and independent t-tests for inter-group comparisons, with effect size estimation using Cohen's<i>d</i>. For all statistical tests, we used<i>α</i> = 0.05.<i>Results</i>. The increase in vaginal pressure was significantly greater in Group A than in Group B. Group A showed a mean pressure gain of 15.2 ± 3.5 mmHg (<i>p</i> < 0.001), whereas Group B showed a mean gain of 7.8 ± 2.9 mmHg (p = 0.002). The inter-group difference was statistically significant (p = 0.004), with a large effect size (Cohen's d = 2.2). Conclusion: Preliminary data suggest that the mobile pen-like electrode is associated with a greater increase in vaginal pressure in asymptomatic volunteers compared to fixed patch electrodes. Although limited by the small sample size and the absence of a clinical population, the findings indicate that the developed device may represent a promising alternative for perineal rehabilitation, warranting validation in larger, blinded clinical studies.