Assessment of the vaginal microbiota before and after use of hyperosmolal lubricant during transvaginal ultrasound.

Background: Vaginal lubricants are commonly used during sexual activity and clinical procedures such as transvaginal ultrasound. Epidemiologic and laboratory studies indicate hyperosmolal water-based lubricants may disrupt the vaginal microbiota, particularly the beneficial Lactobacillus spp. These bacteria play a critical role in protecting against sexually transmitted infection acquisition and other adverse gynecologic and obstetric outcomes.

Objective: We sought to evaluate changes in the composition of the vaginal microbiota before and after a single exposure to lubricant over a 10-week period among pre-, peri-, and postmenopausal patients referred for transvaginal ultrasound.

Study Design: One hundred four participants self-collected mid-vaginal swabs daily between baseline and transvaginal ultrasound (∼1 week), immediately before transvaginal ultrasound ("pre-transvaginal ultrasound"), and 6 to 12 hours after transvaginal ultrasound ("post-transvaginal ultrasound"). Participants attended a follow-up visit ∼2 to 5 days after transvaginal ultrasound ("post-transvaginal ultrasound follow-up"), continued to self-sample twice-weekly for 9 weeks, and attended a final clinical visit in week 10. Microbiota composition was characterized by 16S ribosomal RNA gene amplicon sequencing (V3-V4) and assigned to community state types (low-Lactobacillus vs Lactobacillus-dominated). Yue-Clayton theta indices defined similarity between daily successive samples between baseline and transvaginal ultrasound and overall stability of the vaginal microbiota before and after transvaginal ultrasound. Analysis of Compositions of Microbiomes II determined differentially abundant taxa in post-transvaginal ultrasound samples vs pre-transvaginal ultrasound samples. Generalized linear mixed models evaluated the odds of having a low-Lactobacillus microbiota after transvaginal ultrasound with samples before transvaginal ultrasound as the reference for each participant.

Results: A majority of the cohort was premenopausal (85/104, 82%) and self-reported Black race (65/104, 62%). Over the short-term (1 week), there was no immediate changes in the composition of the microbiota of daily successive samples following transvaginal ultrasound. In contrast, over the longer-term (participants followed for 10 weeks), the vaginal microbiota was less stable within intervals after transvaginal ultrasound vs the interval before. There were no changes in the odds of a low-Lactobacillus microbiota after transvaginal ultrasound among all participants in this 10-week longitudinal study. However, in specific groups such as peri/postmenopausal participants (N=19, adjusted odds ratio: 3.22, 95% confidence interval:1.16-8.98) and those with a history of bacterial vaginosis (N=58, adjusted odds ratio: 1.73, 95% confidence interval:1.10-2.72), there was a higher likelihood of persisting in a low-Lactobacillus state throughout the follow-up period.

Conclusion: Peri- and postmenopausal individuals and those with a history of bacterial vaginosis show a sustained decrease in protective Lactobacillus spp. after a single exposure to hyperosmolal vaginal lubricant. Reformulating water-based lubricants to reduce osmolality and toxicity may be beneficial.