Evaluating non-invasive Preimplantation Genetic Testing for Aneuploidy (niPGT-A) from spent culture medium: prolonged embryo culture to day 6 increases informativity without negatively impacting quality and live birth rates.

PURPOSE

Embryos release cell-free DNA into spent culture medium (SCM), mostly from day 5 to day 6, making extended culture to day 6 (something done in IVF only for slow embryos) a preferred option in non-invasive preimplantation genetic testing for aneuploidy (niPGT-A). The impact of day 6 culture on embryo quality remains unclear. This study investigates whether prolonged culture to day 6 in niPGT-A improves informativity without compromising embryo quality and live birth rates (LBR).

METHODS

In this retrospective cohort study, we investigate the impact of day 6 culture on embryo quality and LBR. After preliminary concordance assessment on 18 embryos, a total of 336 SCM from day six blastocysts were collected. According to the prioritisation criteria applied, 103 embryos were transferred in 91 frozen embryo transfer cycles (January 2021-February 2024). Informativity rates in day 5/6, levels of expansion/quality, female age impact and effects of prolonged culture to day 6 on embryo quality were assessed.

RESULTS

Higher informativity rate was observed in day 6 versus day 5 blastocysts (p < 0.001). Informativity was unaffected by different age groups (p = 0.22), blastocyst expansion (p = 0.51), blastocyst quality (p = 0.67), or incubator setting (p = 0.74). Day 6 prolonged culture did not compromise embryo viability and quality and better quality embryos had higher probability of euploidy (p = 0.01). We report a LBR of 33.3%, higher than the reported 10% by HFEA for a similar age group (40-42 years).

CONCLUSIONS

Day 6 extended culture in niPGT-A improves informativity and does not compromise embryo viability and quality. LBR significantly increased compared to international benchmarks of non-tested embryos.