Chronic Endometritis: Old Problem, Novel Insights and Future Challenges

Background/Aims: Chronic endometritis (CE) is a poorly investigated pathology that has been related to adverse reproductive outcomes, such as implantation failure and recurrent miscarriage. In this paper we aim to provide an overview about diagnosis, etiology, pathophysiology and treatment of CE, its impact on endometrial microenvironment and how it may be associated with infertility. Methods: Narrative review of the current literature, synthesizing the findings retrieved from searches of computerized databases. Results: CE is more prevalent in infertile patients. Effective antibiotic treatment of CE seems to improve the per pregnancy live birth rate in patients with unexplained recurrent pregnancy loss, and increase ongoing pregnancy rate in patients with recurrent implantation failure. In order to increase the diagnostic accuracy, immunohistochemistry is recommended besides conventional histology. In addition, hysteroscopy could be considered the gold standard tool for the diagnosis, considering its high correlation with histological findings. Conclusion: CE is the chronic inflammation of the endometrium, usually asymptomatic and probably underestimated. Interaction between bacteria and endometrial microenvironment promotes changes in leukocyte population, cytokine production and growth factors which support its negative impact on endometrial receptivity. Nevertheless, standardization of the criteria for histopathological diagnosis and immunohistochemistry technique needs to be defined.