Endometrial receptivity: from biosensor to clinical practice

What was shown

A challenge to the 'all in the egg' narrative built around the Pirtea / Atta papers that reported up to 95% cumulative pregnancy with serial euploid transfers. The talk reframes endometrial receptivity as a continuum rather than a binary on/off, and introduces the biosensor concept: stromal cells migrate towards good-quality embryos and stay back from poor-quality ones.

Key findings

In a Rotterdam high-resolution cytogenetic study, 82% of normally developing blastocysts labelled euploid by commercial tests carried some mosaicism. In vitro, decidualised stromal cells migrate to engage with good blastocysts and remain static around poor ones. In endometrium from women with recurrent miscarriage, this discrimination is lost — stromal cells engage with poor embryos too, allowing implantations that should not have happened. The 95% cumulative figure of Pirtea / Atta is biased by serial drop-out and does not generalise to the typical RIF clinic.

What this means in practice

Stop framing the endometrium as receptive or non-receptive. Plan a diagnostic toolbox that separates receptivity from selectivity from incubator function from microbiome from secretion composition. Be cautious with super-receptive interventions: in a poor-quality embryo cohort they can convert an implantation failure into a clinical miscarriage. Heparin and metformin-related compounds may already act partially through biosensor modulation.

Caveats

All the migration data come from in-vitro scratch models. Recurrent implantation failure remains a clinical phenomenon that needs management, even if redefined; the 'less than 5%' Lugano 2023 figure is contested. Endometrial biosensor testing is not yet a clinical product.