THE ENDOMETRIAL RECEPTIVITY ASSAY IMPROVES PREGNANCY RATES IN PATIENTS UNDERGOING FROZEN EMBRYO TRANSFERS

Abstract

To determine the benefit of the endometrial receptivity assay on clinical pregnancy rates in patients undergoing frozen embryo transfers. A retrospective cohort analyses was performed of all patients who underwent an endometrial receptivity assay (ERA) between 7/2014 and 9/2020 at a single academic fertility center. The primary objective was to assess the clinical pregnancy rate, defined as a fetal heart rate after 6 weeks of gestation, following correction of progesterone time to first frozen embryo transfer (FET) following ERA. Information collected also included endometrial thickness (ET) at time of ERA, ET at subsequent first FET, if the ERA was performed prior to a FET or after 1 or more failed FETs, and the number of euploid embryos the patient had available for transfer. Data was analyzed using Pearson’s chi-square tests. A total of 234 patients underwent an ERA procedure, of which 223 led to a result. Of the 223 patients with an ERA result, 158 underwent a FET following the ERA. The receptive pregnancy rate was 54.5% for the 88 patients who had a receptive result. The non-receptive pregnancy rate was 71.4% after progesterone time correction for the 70 patients who had a non-receptive result. The clinical pregnancy rate was statistically significantly greater in the non-receptive group following progesterone correction, with a p-value of 8.70603E-12. Of the receptive patients, 114 or 91.2% had an ET of 6-12 mm versus 102 or 82.3% of nonreceptive patients. ET did not correlate with receptivity (p-value of 0.63). A subset of the data between 1/2018 and 9/2020 was analyzed to see how many patients performed an ERA before ever having a FET. There were 133 patients who underwent an ERA procedure during this time and 88 patients, or 64%, underwent an ERA before every having a FET, of which 44% had only 1 euploid embryo available for transfer. The non-receptive rate among all patients who had an ERA was 45%, which is higher than the reported rate. We were rewarded by a clinical pregnancy rate of 71.4% in the non-receptive group, which is statistically higher than the receptive pregnancy rate of 54.5%. However, the receptive pregnancy rate was comparable to the clinical pregnancy rate of 54% per FET at our fertility center. Hence, the ERA improves clinical pregnancy rates among patients with a non-receptive endometrium, leading to a pregnancy rate that is even greater than that of patients with a receptive endometrium after corrected progesterone exposure time. Most importantly, the majority of the patients who underwent an ERA in this study never had an embryo transfer, and hence a history of failed FET, prior to performing the ERA. Thus, this data suggests that performing an ERA on all patients undergoing a FET has a benefit in improving clinical pregnancy rates, and may have both an emotional and financial benefit for the patient.