Influence of the Normal Menstrual Cycle on Vaginal Tissue, Discharge, and Microflora

Abstract

The objective of this study was to examine genital tissue, vaginal fluid, and vaginal microbial flora at 3 phases of the menstrual cycle in asymptomatic women.Vaginal examinations were performed 3 times in 74 women: at the menstrual phase (days 1-5), the preovulatory phase (days 7-12), and the postovulatory phase (days 19-24).Flora of 50 women without bacterial vaginosis (BV) was analyzed separately from flora of 24 women with BV.The volume of vaginal discharge increased and the amount of cervical mucus decreased over the menstrual cycle.Among subjects without BV, the rate of recovery of any Lactobacillus changed little (range, 82% to 98%;); however, a small increase occurred in the rate of recovery of P = .2heavy (3+ to 4+ semiquantitative) growth of Lactobacillus over the menstrual cycle ( ).P = .04A linear decrease occurred in the rate of recovery of heavy growth of any non-Lactobacillus species, from 72% at days 1-5 to 40% at days 19-24 ( ).A linear decrease also occurred P = .002in the rate of recovery of Prevotella species, from 56% on days 1-5 to 28% on days 19-24 ( ), while a small linear increase occurred in the rate of recovery of Bacteroides fragilis P = .007( ).Among subjects with BV, the only significant change was an increase in the rate of P = .05recovery of Lactobacillus, from 33% at days 1-5 to 54% at days 19-24 ().Among all P = .008subjects, the rate of recovery of heavy growth of Lactobacillus increased over the menstrual cycle and, in contrast, the concentration of non-Lactobacillus species tended to be higher at menses, which is evidence that the vaginal flora becomes less stable at this time.Many sexually transmitted diseases are transmitted more efficiently from men to women than from women to men [1,2].The vagina represents a critical portal of entry for most sexually transmitted diseases in women.Both a low pH in the vagina and the microbicidal effects from H 2 O 2 produced by vaginal Lactobacillus [3,4] appear to inhibit many genital infections.Little is known, however, about normal physiological variation in the vagina over the menstrual cycle or how this variation may alter the acquisition of genital or systemic infection.In this study, we examined vulvar and vaginal tissue specimens grossly and by colposcopy, measured the amount of cervical and vaginal fluid, and evaluated vaginal flora for 74 asymptomatic women free of gonorrhea, chlamydial infection, trichomoniasis, and symptomatic candidiasis during 3 phases of the