Intestinal microflora provides biomarkers for infertile women with endometrial polyps

Endometrial polyps (EPs) are related to infertility; however, there are no biomarkers for identification. We evaluated changes in the intestinal microflora to identify microflora-based biomarkers that may be useful for detecting EPs. Intestinal specimens were prospectively collected from 100 women: 25 infertile women with EPs (InfEP + group), 25 infertile women without EPs (InfEP- group), and 50 healthy women (Fertile group). The microbiota composition was analyzed using 16S ribosomal RNA gene amplification and the intestinal expression of selected human genes using quantitative reverse transcription polymerase chain reaction. The InfEP + group had higher proportions of Prevotella, Streptococcus, Fusobacterium, Fenollaria, and Porphyromonas than the InfEP- and Fertile groups, while the Fertile group had higher proportions of Faecalibacterium, Bacteroides, and Blautia. We constructed a microbial dysbiosis index based on the intestinal microbiota at the genus level as a predictive model. The most accurate model to predict the presence of EPs was that including the Fertile and InfEP + groups (area under the curve: 0.89, 95% confidence interval: 0.79–0.96). The InfEP- and Fertile groups had significant differences in microflora composition compared with the InfEP + group. The intestinal microflora may be a useful biomarker for identifying EPs in infertile women.