Chronic Endometritis and Endometrial Polyps in Female Infertility: Etiological Mechanisms, Diagnostic Insights, and Prognostic Implications

Background/Objectives: Endometrial polyps (EPs) are common benign intrauterine lesions associated with abnormal uterine bleeding, infertility, recurrent implantation failure, and recurrent pregnancy loss. Although traditionally considered hormone-dependent lesions, increasing evidence suggests that chronic endometritis (CE) may contribute to their development and recurrence. This review summarizes current evidence regarding the relationship between CE and EPs, focusing on pathophysiological mechanisms, diagnostic approaches, and clinical implications. Methods: This narrative review was conducted according to the Scale for the Assessment of Narrative Review Articles (SANRA). A literature search was performed using PubMed/MEDLINE, Scopus, and Google Scholar to identify original studies, systematic reviews, meta-analyses, and consensus statements addressing CE, EPs, infertility, endometrial microbiota, and polyp recurrence. Results: Current evidence demonstrates a consistent association between CE and EPs, with approximately half of premenopausal women with EPs showing histological evidence of CE. Chronic inflammation may promote polyp formation through immune activation, inflammatory cytokine signaling, abnormal angiogenesis, extracellular matrix remodeling, dysregulated apoptosis, and alterations in the endometrial microbiome. CE has also been identified as an independent predictor of EP recurrence after hysteroscopic polypectomy and may impair endometrial receptivity. Histopathological examination with CD138 immunohistochemistry remains the diagnostic reference standard. Conclusions: Emerging evidence supports an inflammatory component in the pathogenesis of endometrial polyps and suggests that CE may represent a potentially modifiable risk factor for recurrence and reproductive failure. Incorporating assessment of CE into the evaluation of selected women with recurrent polyps or infertility may improve individualized management. However, prospective studies are needed before routine screening and treatment can be universally recommended.