P-352 Consequences and prevalence of Bacterial Vaginosis and vaginal leukocytosis on Live Birth rate after IVF - Nugent score : What else?
Authors: Porcu-buisson G , Peel E , Chabert Orsini V , Hairion D , Giorgetti C , Ghione S 
Published: June 2022

Study question

Do altered vaginal microbiota, and vaginal leukocytosis, both estimated by the Nugent score, influence live birth rates in IVF after a fresh embryo transfer?

Summary answer

In our series, Nugent score is able to diagnose Bacterial Vaginosis and predict its bad influence in live birth rates after fresh embryo transfer.

What is known already

For several years, special attention has been given to vaginal microbiota and vaginosis as part of IVF and embryo implantation failure.

Lactobacillus is recognized as dominant in a healthy vaginal microbiota environment while gardnerella is more present in a vaginal microbiota altered and bacterial vaginosis.

While all published studies are mostly meta-analysis, the originality of our study is the number of patients (967) tested in a single laboratory and taken care of by one center only. This study also reports the influence of the microbiota and leucocytosis on LBR.

Study design, size, duration

This study is a retrospective, a non-interventional monocentric cohort study conducted between January 2017 and December 2019. 967 patients benefited from Nugent score for bacterial vaginosis before the start of treatment or within the first week of injections for IVF protocol. No patient was treated by antibiotics.

Participants/materials, setting, methods

The swab obtained during speculum examination and smeared onto a glass-slide was left to dry at room temperature and then Gram Stained and Nugent score were calculated according to recommendations (Nugent et al., 1991). Bacterial Vaginosis (BV) was diagnosed for Nugent scores of 7 –10 (Group 3) and a score of 4 – 6 (Group 2) was considered intermediate flora (Nugent et al., 1991).In the same way, presence and abundance of leukocytes were recorded.

Main results and the role of chance

BV prevalence estimated by Nugent score in the total population is of 6.52% (63/967). There is no difference between the three Nugent groups regarding demographics criteria.

BV in endometriosis population is of 8.07% (18/223), in patients with tubal infertility 10.46% (18/172) and in patients with male infertility 5.51% (17/353).

The presence of Lactobacillus depends on the age and it is (p = 0.4) statistically more present in older patients while the presence of gardnerella depends on infertility indication. Gardnerella is more represented in tubal indications and the difference is statistically significant (p = 0.01).

Concerning leukocytosis (numerous, relatively numerous and few leukocytes) or no (rare leukocytes) the difference is statistically significant between pregnancy and failure after embryo transfer (p = 0.014). Leukocytosis is more involved in vagina when the IVF failed.

BV prevalence in patients who became pregnant after embryo transfer is of 3.47% (8/230) while BV in patients with IVF failure is of 7.22% (48/664) (p = 0.05).

Concerning Live Birth rate, there are statistically significant differences between Group 1 (152/192) and Group 2 (14/24) (p = 0.03), and between Group 1 and Group 3 (8/16) (p = 0.01) but no difference between Group 2 and 3 (p = 0.74). Moreover, in tubal indications, the presence of gardnerella is significantly associated with miscarriage (p = 0.001)

Limitations, reasons for caution

Our study is retrospective, which may introduce several biases despite the size of our sample i.e all infertility etiologies were included and no differences were made based on the ethnic origins of the patients, which may have resulted in biases.

Wider implications of the findings

Nugent score is able to diagnose BV and predict its bad influence in both etiology of infertility and pregnancy outcome after fresh embryo transfer.

Nugent score allows to define intermediate group and vaginal leukocytosis to which special attention should be paid as it may compromise a pregnancy.

Trial registration number

NOT APPLICABLE