ER®map endometrial receptivity study improves reproductive outcomes after previous implantation failure in in vitro fertilisation cycles

Introduction: Repeated failures in in vitro fertilization are a challenge in fertility treatments, especially in cycles with good quality embryos, where the endometrium appears to be the cause of reproductive failure. Targeted diagnostic tests for evaluation of the optimal endometrium before a new transfer remains a challenge for assisted reproduction treatments. The Endometrial Receptivity Map (ER (R) map Pronacera Therapeutics SL, Seville, Spain) test provides new endometrial information to customize the next embryo transfer to improve reproductive outcomes for patients with previous implantation failure. Objective: The main objective is to determine whether there are differences in the ongoing pregnancy rate by embryo transfer (OPR), after previous failed embryo transfers with good quality embryos, between the study group (E) with endometrial biopsy for endometrial receptivity study prior to a new transfer, and the control group (C) with new standard transfer without previous endometrial receptivity study. Material and methods: Observational, analytical, longitudinal, retrospective study of cases and historical controls, conducted in the Assisted Reproduction Unit (ARU) of the Hospital Quironsalud Barcelona, including 104 patients with one or more previous failed embryo transfers with good quality embryos between the periods 2017-2019. Patients with more than one previous failed transfer underwent a diagnostic hysteroscopy, and an analysis was requested with the determination of: lupus anticoagulant, anti-B2-glycoprotein IgG/IgM antibodies, anti-cardiolipin IgG/IgM antibodies, and hereditary thrombophilia as part of the study of implantation failures in the centre. The study group (E), with 55 patients, underwent an endometrial biopsy for the analysis of endometrial receptivity by means of the ER (R) map (Pronacera Therapeutics SL, Seville, Spain) test prior to scheduling a new personalized transfer (pTE) based on the test result; the control group (C), with 49 patients (historical controls), did not undergo endometrial biopsy for the study of endometrial receptivity after one or more failed embryo transfers with good quality embryos, and a new embryo transfer was scheduled according to the centre's standard protocol (sTE). Results: The results of the endometrial receptivity test in the study group were 63.6% receptive and 36.3% non-receptive. The study group had a higher clinical pregnancy rate (PR) than the control group (PR 70.9 vs. 42.8% p<.05), and there was a higher ongoing pregnancy rate (OPR) in the study group (OPR 60 vs. 38.7% p<.05). If we analyse the data according to the number ofprevious failed transfers, the PR and OPR in the study group was higher than in the control group( PR 72.2 vs, 33.3% NS) (NS: non significance), (OPR 55.5 vs. 33.3% NS) after a previous failedtransfer; we also obtained better results in the study group with respect to the control group( PR 84. 2 vs. 56% p<.05), (OPR 73.6 vs. 48% NS) after two previous failed transfers; the resultsafter three or more previous failed transfers were better in the study group (PR 55.5 vs. 27.7% NS), (OPR 50 vs. 27.7% NS). If we eliminate the embryonic factor by analysing only the resultswith euploid embryo transfers and/or oocyte donation, the PR and OPR were higher in the studygroup vs the control group (PR 71 vs. 47% NS), and (OPR 60.53 vs. 41.17% NS) respectively. Conclusions: The study of endometrial receptivity prior to a new transfer improves reproductiveresults in patients with previous implantation failure, with respect to the control group in whichwe did not carry out an endometrial study. (c) 2021 Elsevier Espana, S.L.U. All rights reserved.