Das intrauterine Mikrobiom – Schrödingers Katze der Reproduktionsmedizin: Die Bedeutung des intrauterinen Mikrobioms für die embryonale Implantation

Background: Successful embryo implantation in the endometrium is a multilayered and complex process and initially represents a major challenge in the vulnerable time period following fertilization of the oocyte, in which the majority of treatment attempts at in vitro fertilization (IVF) fail. A prerequisite for the accomplishment of nidation is a coordinated interplay between a developmentally competent embryo and a receptive endometrium. Furthermore, other factors, such as the bacterial colonization of the internal genitalia, could play a role in this complex cascade. Objectives: The aims of this work are the determination and the summary presentation of the knowledge on the association of the intrauterine microbiome and human embryo implantation. Material and methods: For this review article a structured literature search was carried out in the following databases: the Cochrane Library, PubMed, and Google Scholar. The following keywords were used in various combinations for searching: “endometrium”; “implantation”; “microbiome”; “infertility”; “intrauterine microbiome”. Based on the relevance to the topic and up to date study results a total of 48 articles were included in the evaluation. Results: Neither the physiological nor the pathologically deviant intrauterine microbiome has so far been adequately defined. The relevance of the attempt at the determination of the microbiome as a predictive factor for the success of IVF treatment or as the foundation for a targeted antibiotic or probiotic treatment is unclear. Conclusion: Future studies require larger comprehensively phenotyped cohorts to achieve a better description of the association between the intrauterine microbiome and successful implantation. The immediate importance of the endometrium for reproductive medicine needs to be verified in clinical randomized (placebo-controlled) interventions.