Association Between Hydrosalpinx and Detection of Gram-Positive Anaerobic Cocci in the Endometrial Microbiota: A Single-Center Retrospective Observational Study.

PurposeTo investigate whether hydrosalpinx is associated with alterations in the endometrial microbiota and detection of gram-positive anaerobic cocci (GPAC)-associated genera.MethodsThis single-center retrospective observational study included 236 patients who underwent endometrial microbiota testing by 16S ribosomal RNA gene sequencing: 90 with untreated hydrosalpinx diagnosed by hysterosalpingography and 146 without hydrosalpinx. GPAC positivity was defined as detection of at least one of Anaerococcus, Finegoldia, Peptoniphilus, Peptostreptococcus, or Parvimonas. Logistic regression was adjusted for age, antibiotic use within 3 months, and luteal-phase sampling. False discovery rate adjustment was applied across four exploratory microbiota outcomes.ResultsGPAC-associated genera were detected in 23/90 patients (25.6%) with hydrosalpinx and 19/146 (13.0%) without hydrosalpinx. Hydrosalpinx was nominally associated with GPAC detection (adjusted odds ratio, 2.20; 95% confidence interval, 1.10-4.38; p = 0.025), but not after false discovery rate adjustment (q = 0.101). No clear associations were observed for the other microbiota outcomes. Similar estimates were obtained after additional adjustment for recurrent implantation failure and in post hoc sensitivity analyses using alternative GPAC definitions.ConclusionHydrosalpinx was associated with more frequent detection of GPAC-associated genera in exploratory analyses. This finding should be considered hypothesis-generating rather than confirmatory and requires independent prospective validation.