Conditions for improved accuracy of noninvasive preimplantation genetic testing for aneuploidy: Focusing on the zona pellucida and early blastocysts.

Purpose: Recently, noninvasive preimplantation genetic testing for aneuploidy (niPGT-A) using cell-free deoxyribonucleic acid has been developed; however, there are few reports on this and the results are inconsistent. This study was conducted to optimize the cultural environment.

Methods: We used 35 blastocysts that had been discarded after in-vitro fertilization. The concordance rate of karyotype analysis results between whole embryos (WEs), spent culture mediums (SCMs), and trophectoderms after 8, 16, and 24 h of culture was examined. Next, zona pellucida (ZP)-free blastocysts and then early blastocysts were cultured for 24 h each.

Results: Regarding the optimal culture times, the concordance rate between WEs and SCMs was 20%, 60%, and 100% at 8, 16, and 24 h, respectively. Significant differences were found between 8 and 24 h. The concordance rate with ZP cultures was 40.0%, and no significant differences were found. The concordance rate of early blastocysts thawed and cultured for 24 h was 40.0%, which was significantly lower than that of day 5 blastocysts.

Conclusions: The optimal culture times for niPGT-A were 24 h, and the concordance rate with free ZP was higher. The concordance rate for early blastocysts was low, suggesting that optimization of the conditions may be necessary.