Lack of association between the length of anogenital distance and vaginal pH in women with endometriosis

Abstract

Aim: We investigated the association between the length of anogenital distance (AGD) and intra-vaginal pH, an indicator of vaginal eubiosis or dysbiosis, in women with endometriosis.

Methods: A prospective cohort study was performed including patients with (n = 67) and without (n = 40) endometriosis undergoing surgery between July 2021 and June 2022. AGD was measured from the posterior fourchette to the center of the anus using digital caliper and vaginal pH was measured by inserting pH paper strip mostly into the posterior fornix.

Results: There was no significant difference in the median AGD among control women (n = 40) (21.5 mm), women with revised-American Society of Reproductive Medicine stage I-II endometriosis (n = 27) (22.0 mm) and stage III-IV endometriosis (n = 40) (20.0 mm). In contrast, a significant difference of vaginal pH was observed among groups (p = 0.012) and between groups: control versus stage I-II, p = 0.004; stage I-II, versus stage III-IV, p = 0.037. After adjusting different confounding variables, the univariate analysis showed that women with endometriosis are less likely to have an alkaline vaginal pH (≥4.5) (OR [95% CI] = 0.40 [0.17, 0.93], p = 0.034). Multivariate analysis revealed that AGD or any of the other variables did not serve as an independent risk factor to predict the presence of endometriosis.

Conclusions: This study with Japanese women suggests a lack of association between length of AGD, either shorter or longer, and the status of vaginal pH or the presence of endometriosis in pelvis.

Keywords: anogenital distance; endometriosis; risk factor; vaginal pH.