Chronic Endometritis and Recurrent Pregnancy Loss: A review of evidence and underlying mechanisms

This narrative review aims to evaluate the relationship between chronic endometritis (CE) and recurrent pregnancy loss (RPL). A comprehensive, non-systematic search on the association between RPL and CE was conducted in the PubMed, Cochrane, and SciELO databases, considering its pathophysiological mechanisms, diagnosis and pregnancy outcomes after treatment. The following terms were used as keywords: ("chronic endometritis" OR "endometrial inflammation" OR "subclinical endometritis") AND ("recurrent pregnancy loss" OR "recurrent miscarriage" OR "pregnancy outcomes"). Diagnostic hysteroscopy can be useful for identifying CE based on visual findings (e.g., edema and endometrial micropolyps). However, specificity and sensitivity vary, and it is ideally complemented by biopsy. The identification of plasma cells using the CD-138 marker is the most accurate method for diagnosing CE. Standardization is still needed for the number of plasma cells considered diagnostic and for the quality of CD-138. Tests such as next-generation sequencing and real-time PCR can identify microorganisms and aid in the development of appropriate treatments. Antibiotic regimens have shown efficacy in reducing CE and have a positive impact on pregnancy outcomes in women with RPL. In conclusion, CE appears to be a significant but often underdiagnosed contributor to RPL. Advancements in diagnostic techniques have improved the accuracy of CE identification. Evidence suggests that effective antibiotic treatment not only resolves CE but also enhances pregnancy outcomes in affected women.