Characterizing Vaginal Micro-architecture via OCT, a Validation Study

Objectives: Optical coherence tomography (OCT) is an innovative technique to survey vaginal epithelial micro-architecture in a non-invasive manner. It can measure epithelial thickness, vascular density and elasticity. It may be a feasible alternative to conventional biopsies. We aimed to further validate OCT technology looking at changes in vaginal epithelial thickness (VET) and blood vessel density (BVD) throughout a woman’s reproductive lifespan.

Methods: This was an observational cohort study. Subjects were enrolled if they were more than 18 years old, not pregnant or breastfeeding, and not on hormonal replacement therapy or vaginal estrogen for at least 3 months. Subjects were divided into 3 groups, premenopausal, perimenopausal and postmenopausal. Perimenopause was defined by the STRAW criteria. Subjects completed the vulvovaginal symptoms questionnaire (VSQ) and vaginal health index (VHI). OCT images were collected at four points in the vagina: proximal anterior and posterior, distal anterior and posterior (Figure 1). A U-net deep learning model was applied to obtain VET measurements. OCT angiography (OCTA) images were obtained at the same locations (Figure 2) and ImageJ software was used to calculate BVD percentages. Logistic regression and MANOVA tests were used to compare outcome measures.

Results: Eighty-one subjects were enrolled; 28 premenopausal, 23 perimenopausal, and 30 postmenopausal. Mean ages were 31.2, 49.9, and 61.1 respectively. The majority of subjects were White/Caucasian (52%), primarily non-smokers (92.6%), with an average BMI of 25.8. Medians of the average combined scores showed a decreasing VET from pre to post menopause; 276.64µm, 237.64µm, and 141.26µm respectively. All four individual VET score averages significantly decreased through menopausal stages (p < .0001). BVD median scores were similar in the three groups at 25.7%, 27.3%, and 26.2%. Average distal anterior, proximal posterior, and distal posterior BVD measures were highest in perimenopausal women. BVD scores were not significantly different across groups. VHI and VSQ scores showed moderate correlations with each measured VET.

Conclusions: Optical coherence tomography can identify differences in the vaginal micro-architecture, specifically VET and BVD. In this study, BVD was not shown to change significantly through changes in menopause status. To our knowledge this is the first study to characterize BVD in perimenopause. One limitation of OCT is that vaginal folds may obscure parts of the lamina propria, so a closer look at BVD characterization will be warranted. These results will allow us to further fine tune this technology. Foreseeable applications include research, diagnostics, and assessment of treatment efficacy.