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.
Embryo quality as a continuum, not on/off
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 endometrium as a biosensor
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.
The ESHRE 2023 RIF consensus
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.
Clinical strategy
For morphologically perfect embryos the endometrial factor plays a minimal role. For average-quality embryos it becomes critical. Replacing blanket immunosuppression (steroids, intralipid) with targeted endometrial work-up and phenotype-specific interventions converts «cause unknown» into a manageable clinical category.
A distinct place goes to immune profiling of the endometrium. The speaker contrasts "blind" immunosuppression (systemic steroids, intralipid) given "just in case" with a targeted assessment of local immune status. The point is not to suppress immunity in general but to understand whether a given endometrium tips the balance toward excess receptivity or excess selectivity, and to intervene precisely.
The practical upshot is a table of clinical decisions for repeated euploid-transfer failures: it links endometrial phenotype and embryo quality to a specific course of action — from receptivity work-up to correcting the implantation window. Such an algorithm turns a vague "cause unknown" into a list of testable hypotheses.
For counselling the couple this also changes the language: instead of promising a "perfect embryo," an honest explanation that even a morphologically flawless blastocyst exists on a quality continuum, and that the implantation outcome is decided by the dialogue between embryo and endometrium. Realistic expectations lower the risk of premature treatment dropout.
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?"
Patients arrive at the clinic already having consulted ChatGPT, and regulators are reviewing the first AI ‘doctors’. What in artificial intelligence already works in reproductive medicine — from assistant avatars to embryo assessment and stimulation personalisation? A live discussion on three levels — strategy, service and clinic — with practical cases and a panel Q&A.
A Sona-Pharm grant award for specialists in infertility treatment. Applications open on 1 February 2027. Ceremony — July 2027, Stockholm, during the ESHRE meeting.
Targeted, biomarker-guided immunotropic therapy in reproductive medicine. A lecture by Kseniia Khazhylenko at the UARM Symposium 2026.
Audio: UASubtitles: UA32 min
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