Diagnosis of chronic endometritis: How many CD138+ cells/HPF in endometrial stroma affect pregnancy outcome of infertile women?

Abstract

Problem: The definition of chronic endometritis (CE) differs among studies, and currently, there is no accepted consensus. This study aimed to establish the minimum number of immunohistochemical analysis of CD138⁺ plasma cells to identify a clinically relevant CE.

Method of study: We performed a retrospective study on 716 infertile patients who never did CE analysis and respective antibiotic treatment before. Samples were obtained by endometrial scratching in the mid-luteal phase before IVF-ET treatment. The number and distribution of CD138⁺ cells were analyzed by immunohistochemistry. Thirty high-power fields (HPF) were evaluated for each sample. Patients were classified in 2 main groups: (a) CD138^low (<5 CD138⁺ cells in all HPFs), (b) CD138^high (≥5 CD138⁺ cells in at least one HPF). Pregnancy outcome was compared among the groups.

Results: In the CD138^high group, β-hCG positive rate, clinical pregnancy rate and live birth rate were significantly decreased (P = .04, P = .01, P = .04, respectively). Also after adjusting for patient age, body mass index (BMI), and clinical characteristics, the β-hCG positive rate (P = .05), clinical pregnancy rate (P = .01) and live birth rate (P = .02) were significantly lower in the CD138^high than those in the CD138^low group. Within the CD138^low group, these parameters were not significantly different between patients without any plasma cells and patients with up to 4 plasma cells/HPF.

Conclusion: We conclude that immunohistochemical analysis of CD138⁺ cells is a reliable method to detect CE which can be identified by the presence of ≥5 plasma cells in at least one out of 30 HPF.

Keywords: CD138; chronic endometritis; infertile women; pregnancy outcome.