Change in Vaginal Flora as Indicated by Pap Smear (Schröder’s Classification) in Women Using Levonorgestrel-Releasing Intrauterine System “Mirena”—Prospective Cohort Study

Abstract

Background: The use of intrauterine device alters the normal balance between vaginal flora. It might change cervicovaginal environment, which was suggested to increase the risk for vulvovaginitis. It was found that up to 85% of levonorgestrel-releasing intrauterine system users become amenorrheic 4 months after insertion, or bleed only sporadically. It was hypothesized that this would have a beneficial effect on vaginal flora maintaining normal balance. Objectives: The aim of this study was to detect the effect of hormonal intrauterine system (“Mirena”: 20 microgram/24 hours intrauterine delivery system Levonorgestrel) on vaginal flora by using pap smear before and 6 months after insertion. Study design: A prospective cohort study was carried out in a university maternity hospital. 210 subjects were included with pap smear taken at time of insertion of IUS “Mirena” and another one taken 6 months later to detect percentage of incidence of infection in IUS users. Vaginal flora was studied, and lactobacilli were graded according to Schr?der’s classification. A comparison was made to allow detection of changes in vaginal flora caused by presence of hormonal IUS “Mirena”. Results: Over half of cases (57.2%) showed worse vaginal flora after hormonal IUS “Mirena” insertion than before. There was a highly statistically significant difference between Schr?der’s Grades before and after insertion (P value < 0.001) as 44.8% of cases presented by Grade I, 44.4% of cases presented by grade IIa, 38% of cases presented by grade IIb before insertion developed Grade III after insertion. Conclusion: Insertion of hormonal IUS “Mirena” results in significant change in microbial flora towards pathological bacteria.