Adverse impact of CD138+ cells in proliferative-phase endometrium on pregnancy outcomes in fresh IVF/ICSI cycles

To evaluate the impact of Syndecan-1 (CD138) in proliferative-phase endometrium on pregnancy outcomes in fresh in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI) cycles. This retrospective cohort study contained 273 patients who underwent IVF/ICSI with fresh embryo transfer following an endometrial curettage from January 2020 to May 2022. Endometrial curettage was performed on all patients within 3 to 5 days following menstruation and endometrial tissue was acquired for detection of plasma cells by immunohistochemistry. Subsequent pregnancy outcomes of all cycles were traced and analyzed. A total of 149 patients became pregnant (i.e., pregnant group) in the fresh transfer IVF/ICSI cycles and 124 did not become pregnant (i.e., nonpregnant group). The number of CD138 + cells/ high-power field (HPF) of the nonpregnant group was significantly higher than the pregnant group (2.36 ± 4.24 vs 1.31 ± 3.41, P = .008). The cut off value of CD138 + cells/HPF was 2 by receiver operating characteristic curve analysis, with an area under the receiver operating characteristic curve of 0.572. Compared with the negative group (i.e., CD138 + cells/HPF < 2, n = 204), the positive group (i.e., CD138 + cells/HPF ≥ 2, n = 69) had a significantly lower clinical pregnancy rate (71.8% vs 40.6%, P < .001). The clinical pregnancy rate revealed a gradually decreasing trend with the increase in CD138 + cells. Proliferative-phase endometrial CD138 + cells may be an adverse indicator for pregnancy outcomes in fresh IVF/ICSI cycles, with a certain value in predicting non-pregnancy. Pregnancy outcome was poor when CD138 + cells/HPF ≥ 2 in the endometrium and may worsen with the increase in CD138 + cells.