Molecular diagnosis of bacterial vaginosis: impact on IVF outcome

Bacterial vaginosis can increase obstetrical complications such as miscarriage, premature rupture of membranes and preterm delivery. The aim of our study was first to assess BV prevalence for infertile patients treated by in vitro fertilisation (IVF) using both the Nugent score and polymerase chain reaction (PCR), and then to assess the impact of BV on the pregnancy rate after IVF. Vaginal samples were obtained from women followed for IVF in our Assisted Reproduction Technology (ART) Unit between August 2010 and April 2011. For each patient, two techniques were performed to diagnose BV: Gram staining to assess the Nugent score and a quantitative molecular analysis using a specific real-time PCR assay. Two groups were studied: normal flora (BV-) and BV (BV+). The primary outcome measure was the implantation rate. The secondary outcomes were clinical pregnancy rate, early and late miscarriage, premature rupture of membranes, preterm delivery, mode of delivery and birthweight. A total of 307 patients were included. PCR revealed a prevalence of BV of 9.45 %. Among women who performed vaginal douching, 22.2 % were BV+, whereas 7.9 % of patients who did not douche were BV+ (p = 0.028). The embryo implantation rate was decreased between the BV- and BV+ groups (36.3 % vs. 27.6 %, p = 0.418), but it was not significant. Obstetrical outcomes did not present significant statistical differences among the groups. Vaginal douching significantly enhanced BV in women treated with IVF. We also observed a non-significant decrease of embryo implantation rate and clinical pregnancy rate for women treated by IVF.