The importance of pelvic floor muscle (Kegel's) exercise in treating women with SUI is beyond description, although requiring proper technique and commitment to performing for a long time to have a better outcome . For women who cannot identify the proper muscle or regularly conduct the exercise, treatments such as electric stimulation and ExMI can be introduced. They both shared the same goal: to strengthen the pelvic floor muscles passively. In the clinical situation, the strong point of the ExMI is convenience and comfort compared to electrical stimulation.
In our observation, most of the current studies that discussed the therapeutic effect of ExMI lack objective measurements. As a result, 1-hour pad test and trans-perineal ultrasound were then performed explicitly in this study. Trans-perineal ultrasound is a cheap, real-time, and non-invasive method to evaluate genitourinary displacement .
In the present study, the incidence of SUI decreased significantly following the treatment. The pad test also showed considerable improvement. The therapeutic effect of SUI was calculated to be 75%. The topography of the bladder neck collected from trans-perineal ultrasound showed no significant improvement over bladder neck hypermobility. These results are reasonable with the primary mechanism of the ExMI, which helps the pelvic floor muscle strengthen by contracting passively. Even though the hypermobility of the bladder neck remains, the stronger pelvic floor muscle can help with the closure of the urethra and compensate for the descent of the bladder neck at straining.
Urinary symptoms related to the detrusor muscle and pelvic plexus nerve systems such as urgency incontinence, incomplete emptying, and hesitancy showed no significant difference after treatment in the study; however, the incidence of frequency had significantly decreased following treatment. The complicated mechanism of electrical stimulation and ExMI treating detrusor overactivity involves stimulating the afferent pudendal nerve or sacral root to inhibit the pelvic efferent (parasympathetic) or activate the hypogastric efferent (sympathetic) .
ExMI penetrates the body tissue, and the magnitude of the field only falls off as the inverse square of the distance, which helps activate deeper proximal nerves that are difficult to reach by electrical stimulation without hurting the skin. Tomonori et al. reported in a review article that for urgency incontinence and mixed urinary incontinence, neuromodulation could be the treatment alternative to drug therapy because of its efficacy and much fewer side effects .
Lubrication, orgasm, and satisfaction had significantly improved following the therapy, although sexual arousal and desire showed no significant difference. The fear of coital incontinence can be a source of frustration, anxiety, and low self-esteem to women with SUI ; eventually, sexual functioning can be affected. Bekker et al. in 2009 mentioned that the improvement in coital incontinence resulted in improvement of sexual function. The present study found similar results where ExMI could significantly improve the pelvic floor muscle and improve female sexual function. It is reasonable to postulate that women would appear to be more willing to relax and enjoy sexual activity when urinary incontinence resolves; on that account, sexual arousal and desire might be improved.
As a result, ExMI can effectively improve SUI by providing pelvic floor muscle stimulation in a painless and convenient (no need for undressing) way. The ability of sexual function change is secondary to the improvement of pelvic floor muscle power. R Lim et al., who performed a one-year follow-up, found high patient acceptance and low dropout rates . This can be interpreted as ExMI being an attractive and promising non-surgical alternative for patients who do not want surgery.
HIFEM (High-Intensity Focused Electromagnetic) is a novel technology that offers supramaximal pelvic floor contraction using focused electromagnetic energy. The supramaximal pelvic floor contraction is brain-independent and beyond physiological contraction in strength and repetitiveness, leading to pelvic floor stimulation, adaptation, and remodeling . HIFEM is conducted with the patient fully clothed and seated. As mentioned in several studies, urinary incontinence and sexual function had significantly improved after HIFEM treatment .
It is worth noting that trans-perineal ultrasound was widely used for its real-time convenience and objectiveness in many recent studies we reviewed. The diameter of the anteroposterior and latero-lateral levator hiatus and hiatal area (HA) were significantly reduced in the group treated with HIFEM technology compared with the group treated with the electrical device .
The FDA (U.S. food and drug administration) approved the indication of the noninvasive Er: YAG laser in the field of urogynecology in 2014. The Er: YAG vaginal laser produces a non-ablative thermal effect that causes the remodeling of vaginal connective tissue and hence, provides the vaginal wall with strength and mechanical traction . The benefit of remodeling can extend to the lower urinary tract anatomy and further improve SUI. Lin KL and Long CY et al. found a significant decrease in the bladder neck mobility via perineal ultrasonography . The mechanism of vaginal laser in treating SUI should be different from ExMI, as it mainly focuses on neocollagenesis and remodeling of connective tissue.
There are some limitations to our study. Firstly, a relatively small number of participants were enrolled; and secondly, a longer follow-up to determine how long the benefits of treatment will be sustained was lacking. A randomized controlled trial including a control group and a larger sample size is necessary to support our findings. However, the strength of our study was applying objective trans-perineal ultrasound measurement instead of subjective questionnaires only.