Purpose: Studies have demonstrated high implantation rates after trophectoderm biopsy of day 5 expanded blastocysts. However, biopsy of cleavage stage embryos may adversely affect embryo development and implantation. No studies have assessed the utility of day 5 morulae and early blastocyst biopsy. This study sought to better understand these slower embryos' aneuploidy rates and implantation potential.
Methods: This was a retrospective review of all autologous IVF cycles utilizing PGS at a single academic infertility center.
Results: The biopsy of day 5 morulae and early blastocysts provided 22 % additional euploid blastocysts available for fresh day 6 transfer compared to day 5 biopsy of only expanded blastocysts. Aneuploidy did correlate with embryo stage on day 5, even after controlling for maternal age, with 16 % of morulae and 35 % of blastocysts being euploid. The majority (83 %) of euploid morulae progressed to the blastocyst stage by day 6. Experience transferring slower developing embryos is limited, but preliminary pregnancy and implantation rates appear similar to euploid embryos biopsied as expanded blastocysts.
Conclusions: The biopsy of all non-arrested embryos on day 5 provides genetic information for all blastocysts on day 6, increasing the pool of euploid blastocysts available for fresh transfer and avoiding the need to cryopreserve developmentally competent embryos without genetic information.