The use of vaginal estriol and its effects on sexual intercourse and serum estriol levels in postmenopausal women

Objectives: Vaginal estrogenization plays a crucial role in alleviating pain during sexual activity while low-dose vaginal estrogen therapy provides benefit often with no increase in systemic estrogen levels after use. This study aimed to compare the effects of estriol applied to the distal or proximal thirds of the vagina on dyspareunia in postmenopausal women, evaluate serum estriol levels, and assess sexual function. Methods: This prospective, randomized clinical trial included a total of 116 sexually active postmenopausal women with dyspareunia who were randomized to receive vaginal estriol (1.0 mg/application, every other day) for 12 weeks in the proximal estriol group (PEG) or distal estriol group (DEG), or a vaginal lubricant gel (VLG) before intercourse. Plasma estriol levels, coital pain (McGill Pain Questionnaire), sexual function (FSFI), and emotional status (HADS) were assessed at baseline and after 12 weeks. Statistical analyses included the Shapiro-Wilk test for normality, one-way ANOVA with Tukey’s post-hoc test, χ 2 test, and Pearson correlation as appropriate. Results: No significant changes in serum estriol levels were observed in any group after the intervention. PEG and DEG showed significant increases in FSFI total scores and all domains. The VLG group showed improvements in FSFI total scores and the domains of desire, arousal, lubrication, satisfaction, and pain. Intergroup analysis revealed that the PEG group showed significantly greater improvement in the lubrication domain compared with DEG (mean difference=0.70; 95% CI: 0.05-1.37; P =0.04) and VLG (mean difference=1.22; 95% CI: 0.58-1.86; P <0.01). All other domains showed no statistically significant differences between groups. Conclusions: Vaginal estriol, applied distally or proximally, improved dyspareunia and sexual function without increasing systemic estriol levels. Lubricant use also enhanced sexual function (except orgasm) and reduced pain comparably to estriol.