Endobiota–Estrobolome Profiles in Reproductive‐Aged Women With Ovarian Endometriosis

Purpose This case–control study investigated whether ovarian endometriosis is associated with altered estrogen metabolism and gut or urogenital microbiota by analyzing enzyme activity, bacterial composition, and variations of estrogen metabolites in fecal, vaginal, and urinary samples. Methods Thirty‐eight reproductive‐aged women were enrolled, including 24 with pathologically confirmed ovarian endometriosis and 14 controls. Stool, urine, and vaginal samples were collected preoperatively. Gut β‐glucuronidase and β‐glucosidase activities were measured, estrogen and 14 metabolites were quantified using liquid chromatography–mass spectrometry, and gut and vaginal microbiota were analyzed by 16S rRNA gene sequencing. Microbial composition, diversity, and abundance were compared between groups. Results Gut β‐glucuronidase activity and overall microbial diversity were comparable between groups; however, the control group showed a higher prevalence of the genus Rothia , whereas several genera, including Megamonas and [Eubacterium] coprostanoligenes_group , were enriched in the ovarian endometriosis group. In contrast, vaginal samples from patients with ovarian endometriosis demonstrated significantly reduced bacterial abundance and diversity, accompanied by lower levels of 4‐methoxyestrone, 2‐methoxyestrone, and 2‐hydroxyestrone‐3‐methyl ether. Conclusions Although overt dysbiosis was not observed, specific microbial shifts and altered estrogen metabolites may reflect disturbances in estrogen metabolism and urogenital–gastrointestinal microbiota in ovarian endometriosis.