Endometrial Microbiome and Implantation: From Basic Knowledge to Clinical Medicine.

Background: Recurrent implantation failure (RIF) is an infertility condition in which uterine factors remain difficult to diagnose and treat. Recent studies implicate the endometrial microbiome in implantation. Methods: This clinically oriented narrative review summarizes female reproductive tract microbiota and evidence on endometrial microbiome testing and management in infertility. Main Findings Results: Vaginal dysbiosis is linked to adverse reproductive outcomes and provides a reference for interpreting upper-tract findings. Endometrial microbial signals are detectable by sequencing, but interpretation is challenged by the low-biomass environment and vulnerability to carry-over, kitome effects, and contamination. Across ART studies, a Conclusion: Evidence is rapidly evolving, yet observational designs and methodological variability limit causal inference. Future progress will require standardized sampling and contamination controls, outcome-anchored threshold validation, and pragmatic real-world evaluations of protocolized test-and-treat pathways using clinically meaningful endpoints.