Background Chronic endometritis (CE) is a persistent inflammation of the endometrium often overlooked due to its asymptomatic presentation. It is increasingly recognized as a factor contributing to infertility, recurrent implantation failure, and recurrent pregnancy loss. Multiple diagnostic methods, including histology, microbiological cultures, and hysteroscopy, are used for CE diagnosis, but their comparative effectiveness in asymptomatic infertile women remains inadequately studied. To evaluate and compare the diagnostic performance of histology, microbiological cultures, and hysteroscopy in identifying CE in asymptomatic infertile women and to assess their impact on post-treatment reproductive outcomes. Methods This prospective observational study included 120 infertile women aged 20 to 40 years with regular menstrual cycles and no symptoms of pelvic infections or uterine abnormalities. Data were collected during the proliferative phase of the menstrual cycle. Endometrial biopsies were obtained and assessed using histology with CD138 immunohistochemistry (gold standard) and microbiological cultures for pathogen diagnosis. Diagnostic hysteroscopy was performed to evaluate visual markers of CE, including micropolyps, hyperemia, and edema. Sensitivity, specificity, and agreement (Kappa coefficient) between modalities were analyzed. Post-treatment reproductive outcomes, such as pregnancy rates, implantation rates, and miscarriage rates, were also assessed. Results Histology identified CE in 31.7% of cases. Microbiological cultures had a lower detection rate (23.3%) with a sensitivity of 73.7% and specificity of 92.1%. Hysteroscopy identified CE in 29.2% of cases, demonstrating a sensitivity of 92.1% and specificity of 88.2%. The highest agreement was observed between histology and hysteroscopy (κ = 0.78), while microbiological cultures showed moderate agreement with histology (κ = 0.71). Post-treatment, 42% of women achieved pregnancy, and implantation rates improved by 38%. However, the reduction in miscarriage rates (12%) was not statistically significant. Conclusion Histology remains the most reliable diagnostic tool for CE but is invasive and resource-intensive. Hysteroscopy offers high sensitivity and is particularly useful where histological assessment is unavailable. Microbiological cultures provide valuable pathogen-specific information but may miss cases of CE without active infection. Combining these diagnostic modalities can enhance CE detection and improve management strategies in infertility care. Future studies should focus on developing non-invasive diagnostic techniques and standardized criteria for CE diagnosis.