Introduction and hypothesis: Evidence and recommendations for the use of intravaginal estrogen for prevention of bacterial vaginosis and pessary-related complications are limited and controversial. We hypothesized that adding intravaginal estrogen to pessary use would decrease the incidence of bacterial vaginosis and other pessary-related complications.

Methods: A single-center, open-label, randomized, parallel study was conducted between April 2018 and August 2020. Participants were randomized to either receive intravaginal estriol 0.03 mg plus Lactobacillus acidophilus 100 million viable cell vaginal tablets or have no treatment. The Amsel criteria, normal flora index, visual analog scale, Thai version of the ICIQ-VS (International Consultation on Incontinence Questionnaire-Vaginal symptoms) questionnaire, vaginal abrasions and vaginal bleeding were evaluated at entry and at 2- and 14-week follow-up.

Results: Seventy-eight women were included and randomized to two groups (39 women per group). At 2-week follow-up, one participant in the intervention group and two participants in the control group were diagnosed with bacterial vaginosis (2.7% vs. 5.7%, p = 0.609). At 14-week follow-up, two participants in the intervention group and two participants in the control group were diagnosed with bacterial vaginosis (5.7% vs. 6.2%, p = 0.926). Normal flora index was significantly different at 2-week follow-up [8 (6.3) vs. 5 (6.0), p = 0.032]. There was no significant difference in the visual analog scale, Thai version of the ICIQ-VS, vaginal abrasions and vaginal bleeding between the 2- and 14-week follow-ups.

Conclusions: This study shows no benefit of intravaginal estrogen in reducing bacterial vaginosis, vaginal abrasions, vaginal bleeding and pain in postmenopausal women using a vaginal pessary for pelvic organ prolapse treatment.