Chronic endometritis as a multifactorial cause of reproductive loss: current diagnostic criteria and therapeutic options

Chronic endometritis is one of the most significant and relevant challenges in reproductive medicine. This disease is associated with reduced pregnancy rates and an increased risk of spontaneous miscarriage and implantation failure in in vitro fertilization. Chronic endometritis is generally asymptomatic, which hiders timely diagnosis and treatment. This review summarizes current knowledge on the pathogenetic mechanisms, diagnostic capabilities, and treatment strategies for chronic endometritis, as well as their impact on reproductive outcomes. The analysis was based on data from 27 publications for 2021–2025 retrieved from international and Russian databases, encompassing meta-analyses, systematic reviews, and original clinical studies. The leading pathogenetic factors of chronic endometritis include microbial dysbiosis characterized by polymicrobial associations, neutrophil hyperactivation with the formation of neutrophil extracellular traps, cytokine imbalance, and activation of the USF2/TREM1 and miR-92b/PTEN signaling pathways. These alterations impair endometrial receptivity and hinder successful embryo implantation. Although a histological examination identifying CD138+ plasma cells remains the diagnostic gold standard, variability in threshold values complicates interpretation. Diagnostic evaluation is further complemented by hysteroscopy and promising noninvasive methods, including artificial intelligence-based analysis of hysteroscopic images and serum biomarker assessment. Antibiotic therapy remains the mainstay of treatment, though its effectiveness is undermined by rising antimicrobial resistance. Modern therapeutic approaches involve the use of recombinant type III collagen and antifibrotic therapy, which improve endometrial structure and receptivity, increasing pregnancy rates up to 73.9%. This review highlights the need for standardization of diagnostic algorithms, integration of molecular technologies, and adoption of combined therapeutic regimens to enhance management efficacy in chronic endometritis and improve reproductive outcomes.