True hysteroscopic features of chronic endometritis: A retrospective case-control study in chronic endometritis and non-chronic endometritis

In this study, we aimed to clarify the findings suggesting the presence of chronic endometritis (CE) on hysteroscopy by comparing cases of CE diagnosed on endometrial biopsy with those judged non-CE on hysteroscopy. The uterine lumen was observed using a hysteroscope, and four discrete findings were recorded: endometrial congestion, micropolyps, endometrial edema, and endometrial polyps. A definitive diagnosis of CE was made based on endometrial histopathology. If more than five CD138 immunohistochemical staining-positive plasma cells were found per 20 high-power fields (HPF) in the endometrial tissue samples, the sample was defined as CE (CE group). Samples with fewer than five plasma cells per 20 HPF were defined as normal (non-CE group). Among the four hysteroscopic findings, only endometrial congestion was a significant contributing factor to the diagnosis of CE based on endometrial histopathology in multivariate analysis. The diagnostic concordance rate of CE for hysteroscopy-positive cases was 53.2 %, while the concordance rate of non-CE for hysteroscopy-negative cases was 55.0 %. Among the hysteroscopic findings that have been reported to be associated with CE, only endometrial congestion is truly indicative of CE.