Observational cohort study of the effect of a single lubricant exposure during transvaginal ultrasound on cell-shedding from the vaginal epithelium

Abstract

The outer layers of the vaginal epithelium (VE) are important because they accumulate glycogen which, under optimal conditions, Lactobacillus spp. consume to grow and acidify the vaginal microenvironment with lactic acid. We hypothesized that exposure to lubricant, for example in the conduct of a transvaginal ultrasound (TVUS), may contribute to the shedding of mature epithelial cells, exposing immature cells. Cervicovaginal fluid (CVF) was sampled at four time points by menstrual cup (Softdisc™) from 50 women referred for TVUS, during which a controlled volume of lubricant was applied to the TVUS wand. Samples were collected (1) immediately before TVUS and (2) 6-12 hours, (3) within one week, and (4) two weeks after TVUS. Clinical vaginal lubricants are similar to commercial lubricants, and often have a high osmolality or pH, and contain bactericides such as methylparaben and propylparaben. The number and maturity of epithelial cells in each CVF sample were measured by quantitative and differential fluorimetry (maturity index, MI). Comparisons of cell-counts and maturity were made by paired Wilcoxon signed-rank tests. Among women with a high pre-TVUS MI (> 3), there was a decrease in median cell-count and mean MI in the sample collected 6-12 hours after TVUS (p<0.001, n = 26 and p < 0.001, n = 26, respectively). For these women, cell-count and MI remained lower in the sample collected within the subsequent week (p<0.001, n = 29 and p<0.01, n = 29, respectively), and MI remained lower in the sample collected within two weeks of TVUS (p<0.01, n = 25), compared to the pre-TVUS sample. Among participants with a low pre-TVUS MI (< 3), cell-count was higher in the sample collected within two weeks of TVUS compared to the pre-TVUS sample (p = 0.03, n = 15), but no significant changes in MI were observed. Results were similar when restricted to reproductive-age women. This preliminary data indicates hypertonic vaginal lubricants may increase vaginal epithelial cell shedding.

Fig 1

A. The vaginal epithelium undergoes morphological changes during maturation. As cells mature, they migrate from the basal layer, to the parabasal and intermediate layers to the superficial layer from which they are shed. B. Morphological changes of the vaginal epithelium during maturation include decrease in nuclear and increase in cytoplasmic sizes, which provides the basis of the Maturity Index value (values shown are representative of each layer). C. Shedding of immature cells indicates depletion of superficial cells, and loss of structural integrity of the vaginal epithelial barrier.

Fig 2. Dashed lines represent change = 0.

Stars represent significant pairwise differences from pre-TVUS samples. A. For all participants, the change in VE cell count per 10 μL CVF in samples taken approximately 12 hours later (post-TVUS), within one week (W1-post-TVUS), and within two weeks (W2-post-TVUS), compared to immediately before TVUS. B. For all participants, the change in maturity index (MI) of samples taken approximately 12 hours later (post-TVUS), within one week (W1-post-TVUS), and within two weeks (W2-post-TVUS), compared to immediately before TVUS. C. For only participants with a pre-TVUS MI > 3, the change in VE cell count per 10 μL CVF in samples approximately 12 hours later (post-TVUS), within one week (W1-post-TVUS), and within two weeks (W2-post-TVUS), compared to immediately before TVUS. D. For only participants with a pre-TVUS MI > 3, the change in maturity index (MI) of samples taken approximately 12 hours later (post-TVUS), within one week (W1-post-TVUS), and within two weeks (W2-post-TVUS), compared to immediately before TVUS. E. For only participants with a pre-TVUS MI < 3, the change in VE cell count per 10 μL CVF in samples taken approximately 12 hours later (post-TVUS), within one week (W1-post-TVUS), and within two weeks (W2-post-TVUS), compared to immediately before TVUS. F. For only participants with a pre-TVUS MI < 3, the change in maturity index (MI) of samples taken approximately 12 hours later (post-TVUS), within one week (W1-post-TVUS), and within two weeks (W2-post-TVUS), compared to immediately before TVUS.

Fig 3. Stars represent significant difference between low MI and high MI samples.

A. Cell-count per 10 μL CVF in samples taken within two weeks of TVUS (W2-post-TVUS) with lubricant exposure, comparing women with a pre-TVUS maturity index < 3 and women with a pre-TVUS maturity index > 3. B. Maturity index of samples taken within two weeks of TVUS (W2-post-TVUS) with lubricant exposure, comparing women with a pre-TVUS maturity index < 3 and women with a pre-TVUS maturity index > 3.