Chronic endometritis diagnosed using a cut-off of ≥5 CD138 plasma cells significantly affects the reproductive outcomes of frozen embryo transfer: a case-control study.

Objective: To investigate the clinical significance of a diagnosis of chronic endometritis (CE) made using a diagnostic cut-off of ≥1 or ≥5 CD138 plasma cells per high power field (HPF) in asymptomatic patients undergoing in vitro fertilization (IVF) with frozen embryo transfer (FET).

Material And Methods: In this retrospective case-control study, 1,865 patients underwent freeze-all-IVF treatment between January and December 2019, with 419 undergoing endometrial biopsies at oocyte retrieval. Of the 419 biopsy-patients, 301 have since undergone first FET.