IntroductionAneuploidity is a widely accepted cause for IVF failure. Emerging data suggests a correlation between morphokinetic paramaters of the early embryo development and its chromosomal constitution. CMA (chromosomal microarray) analysis of IVF embryos contributes a reliable and objective tool, aiding the selection of embryo with better implantation potential. This enables the transfer of a single embryo with consistent pregnancy rates.
AimTo assess the additive prediction value of CMA analysis for embryo selection, compared to the morphokinetic parameters.
Material and methodsA total of 21 PGD embryos, not suitable for reproductive needs, were subjected to blastomeres or trophectoderm biopsy on day 5-6. Single cells underwent whole genome amplification, followed by array hybridization (BlueGenome, 24 sure+) and scanning. CMA results were compared with morphokinetic parameters- PN morphology, timing of embryo's first cleavages, symmetry and synchronization.
ResultsThe chromosomal constitutions of the 21 analyzed embryos were divided into 5 groups: normal chromosomal constitution (3), X monozomy (2), unbalanced translocation (6), single trizomy (3) and chaotic chromosomal constitution (7). Two out of 3 normal euploids embryos were graded with low morphokinetic scores and seven embryos with chaotic chromosomal constitution represented widely variable morphology grades.
ConclusionThis preliminary study demonstrates that determination of the polidity of cleavage stage embryos can be accomplished, at this stage, only by invasive CMA methods. We suggest that assessment of PN and cell cycles parameters are poor predictors for embryo chromosomal constitution. However, other parameters provided by the Time Laps Microscopy, like the initiation of blastulation, may be better ones.
