Proof of concept: preimplantation genetic screening without embryo biopsy through analysis of cell-free DNA in spent embryo culture media.

Objective: To assess whether preimplantation genetic screening (PGS) is possible by testing for free embryonic DNA in spent IVF media from embryos undergoing trophectoderm biopsy.

Design: Prospective cohort analysis.

Setting: Academic fertility center.

Patient(s): Seven patients undergoing IVF and 57 embryos undergoing trophectoderm biopsy for PGS.

Intervention(s): On day 3 of development, each embryo was placed in a separate media droplet. All biopsied embryos received a PGS result by array comparative genomic hybridization. Preimplantation genetic screening was performed on amplified DNA extracted from media and results were compared with PGS results for the corresponding biopsy.

Main Outcome Measure(s): [1] Presence of DNA in spent IVF culture media. [2] Correlation between genetic screening result from spent media and corresponding biopsy.

Result(s): Fifty-five samples had detectable DNA ranging from 2-642 ng/μL after a 2-hour amplification. Six samples with the highest DNA levels underwent PGS, rendering one result with a derivative log ratio SD (DLRSD) of <0.85 (a quality control metric of oligonucleotide array comparative genomic hybridization). The fluid sample and trophectoderm results were identical demonstrating (45XY, -13). Three samples were reamplified 1 hour later and tested showing improving DLRSD. One of the three samples with a DLRSD of 0.85 demonstrated (46XY), consistent with the biopsy. Overnight DNA amplification showed DNA in all samples.

Conclusion(s): We demonstrate two novel findings: the presence of free embryonic DNA in spent media and a result that is consistent with trophectoderm biopsy. Improvements in DNA collection, amplification, and testing may allow for PGS without biopsy in the future.