Liu Y, et al. - Researchers performed a comparison of the prevalence of chronic endometritis (CE) when different diagnostic methods are used. They performed endometrial biopsy precisely 7 days after LH surge (LH+7) and identified plasma cells by means of traditional hematoxylin and eosin (HE) staining and by means of immunohistochemistry (IHC) for Syndecan-1 (CD138). Compared to HE staining, the use of CD138 epitope was more sensitive in identifying plasma cells. The lowest observer variability was noted using plasma cell count per unit area when compared with cell count per ten randomly chosen high-power fields and cell count per section. The prevalence of CE in women with RM, RIF, and Infertility were 10.8%, 7.7%, and 10.4%, respectively, not significantly higher than that of Fertile subjects (5.0%) using this method.