Endometrial immune assessment in patients with a history of previous euploid blastocyst failure.

Background: Influx and establishment of key endometrial immune factors in the mid-luteal phase of the menstrual cycle is paramount for successful embryo implantation. Endometrial immune dysregulation is associated with repeated embryo implantation failure and miscarriage. In Methods: In this retrospective analysis, clinical outcomes were compared between patients undergoing their first euploid transfer in a conventional substituted cycle (n=612), patients undergoing a euploid transfer in a similar cycle after previous euploid failure (n=149) and the study group of patients with previous euploid transfer failure who received a modified endometrial preparatory regimen following endometrial immune profiling targeting uterine natural killer cell recruitment, maturity and activity as well as their key regulatory counterparts (n=37). Results: Significant differences were found between first euploid attempt outcomes and patients with previous failures who didn't use endometrial testing (implantation rate 63% vs 51, Conclusions: Patients who had a failed attempt when using a euploid embryo had lower chances of pregnancy when repeating their treatment, unless they received a personalised endometrial preparation regimen derived from the results of endometrial immune profiling. These preliminary findings indicate the potential value of guiding management based on immune endometrial testing.