The failed implantation of a euploid blastocyst is one of the most demanding clinical scenarios in ART. The contemporary approach reconciles two schools of thought — embryo-centric and endometrium-centric — into a unified framework that explains why, when the embryo is of average quality, the endometrium becomes the rate-limiting factor.
A morphologically excellent blastocyst is not always cytologically perfect. Current research shows that a substantial proportion of good-looking blastocysts carry mosaic changes in at least one cell — a finding that reshapes how clinicians counsel patients and prompts reconsideration of what «ideal embryo» means in clinical practice.
The modern concept treats the endometrium not merely as a passive receiving organ but as an active selective interface. Over-receptive endometrium permits non-viable embryos to implant, producing recurrent miscarriage. Over-selective endometrium rejects viable embryos, producing recurrent implantation failure. With embryos of average quality this balance dictates the clinical outcome.
ESHRE 2023 introduces a practical clinical grading: RIF is diagnosed when cumulative success probability has crossed a defined threshold, adjusted for age and PGT-A status. This shifts diagnosis away from the legacy «three failed transfers» rule toward a contextual, individualised assessment.
The failed implantation of a euploid blastocyst is a clinical problem that bridges two schools of thought: «embryo-centric» and «endometrium-centric». The concept of the endometrium as a biosensor explains why, with embryos of average quality, endometrial receptivity and selectivity determine the outcome. A review of current evidence and the clinical grading of RIF (recurrent implantation failure) per the ESHRE 2023 consensus.
The failed implantation of a euploid blastocyst is a clinical problem that bridges two schools of thought: «embryo-centric» and «endometrium-centric». The concept of the endometrium as a biosensor explains why, with embryos of average quality, endometrial receptivity and selectivity determine the outcome. A review of current evidence and the clinical grading of RIF (recurrent implantation failure) per the ESHRE 2023 consensus.
Move beyond either-or thinking and recognise when the limiting factor is the embryo, the endometrium, or both.
Replace single-cycle odds with cumulative-success tables tailored to age and PGT-A status.
Recognise the over-receptive (recurrent miscarriage) and over-selective (recurrent failure) phenotypes.
Diagnose the endometrial phenotype before applying steroids, intralipid or other add-ons.
Professor and Medical Director of the London Women's Clinic and Co-Chief Editor of Reproductive BioMedicine Online. Internationally recognized for his research on ovarian stimulation, endometrial receptivity and periconception. Author of more than 200 scientific papers.
Author of the lecture "Why euploid embryos fail to implant?"
