Introduction - Morphokenetics by time-lapse analysis was recently added to embryo scoring to assist in their selection. To date, selection of embryos following PGD was based mainly on their dynamic development following biopsy, as assessed by static evaluation on day 4-5, i.e., addition of cells following cleavage and/or compaction.
Aim - To explore the dynamics of the developmental events following blastomere biopsy, by determining their precise timings following culture in the EmbryoScopeTM concomitantly with time-lapse analysis.
Methods – The study group included 234 embryos from PGD treatments (Feb.-Aug. 2013) cultured in the EmbryoScopeTM and the control group included 71 embryos from standard ICSI cycles performed during the same period and cultured in the EmbryoScopeTM until day 5. Time-points of key embryonic events were annotated and analyzed with EmbryoViewer.
Results - 85% of the embryos were biopsied at ≥8 cells. Interestingly, embryos biopsied at the 8-cell stage took longer to progress into subsequent developmental stages compared to those biopsied at <>8 cells (p<0.05). The timing of biopsy in relation to the entrance into the 8 cell may also affect its further development. Comparison with the control group demonstrated that blastomere biopsy significantly delays the timing of compaction (by 4-5h) and the start of blastulation (by 5-10h); (p<0.01).
Conclusion - Analysis of morphokinetic parameters enabled us to explore for the first time, how blastomere biopsy interferes with the dynamic sequence of developmental events. It demonstrates the importance of time-lapse microscopy for determining the optimal timing for blastomere biopsy for improving PGD outcomes.
