The effect of CO₂ laser therapy on vaginal microcirculatory parameters in an animal model for genitourinary syndrome of menopause

BackgroundVaginal laser therapy for the treatment of genitourinary syndrome of menopause (GSM) has been introduced to the market with limited (pre)clinical and experimental evidence supporting its efficacy. It is suggested that vaginal laser therapy increases epithelial thickness and improves vascularization, but the underlying biological working mechanism has not been substantiated yet. ObjectiveTo evaluate the effects of CO2 laser therapy on vaginal atrophy using noninvasive incident dark field (IDF) imaging in a large animal model for GSM. Design, Setting, and ParticipantsAn animal study was conducted between 2018 and 2019 and included 25 Dohne Merino ewes, of which 20 underwent bilateral ovariectomy (OVX) to induce iatrogenic menopause, and 5 did not. The total study duration was 10 months. InterventionsFive months after OVX, ovariectomized ewes received monthly applications of CO2 laser (n = 7), vaginal estrogen (n = 7), or no treatment (n = 6) for 3 months. IDF imaging was performed monthly in all animals. Outcome Measurements and Statistical AnalysisThe primary outcome was the proportion of image sequences containing capillary loops (angioarchitecture). Secondary outcomes included focal depth (epithelial thickness), and quantitative measures of vessel density and perfusion. Treatment effects were evaluated using ANCOVA and binary logistic regression. Results and LimitationsCompared to OVX-only, ewes treated with estrogen demonstrated a higher capillary loops proportion (4% vs. 75%, p < 0.01), and higher focal depth (60 (IQR 60-80) vs. 80 (IQR 80-80) p < 0.05). CO2 laser therapy did not change microcirculatory parameters. As the ewes' vaginal epithelium is thinner than that of humans, it may demand different laser settings. ConclusionsIn a large animal model for GSM, CO2 laser therapy does not affect microcirculatory outcomes related to GSM, whereas vaginal estrogen treatment does. Until more homogeneous and objective evidence about its efficacy is available, CO2 laser therapy should not be adopted into widespread practice for treating GSM.