Symmetry at the 4-cell stage using time-lapse imaging is correlated with embryo aneuploidy

The Influence of Day 2 Blastomere Symmetry on Blastocyst Grade and Ploidy Status

“…Our findings conflict with earlier research which showed that embryos with unevenly sized blastomeres have a lower euploid rate compared to those with evenly sized blastomeres (Hardarson et al, 2001;Ziebe et al, 2003;Buehler et al, 2008;Shenoy et al, 2015). The aneuploid rate in uneven embryos ranged from 54.5% to 76.8% across various studies.…”

“…The aneuploid rate in uneven embryos ranged from 54.5% to 76.8% across various studies. One study employing a similar design to the current study demonstrated a 25% increase in aneuploidy rate following TE biopsy for embryos showing the highest degree of cell symmetry at the 4-cell stage versus those showing the lowest degree of cell symmetry, further finding that cell symmetry was more predictive that time-lapse parameters (Shenoy et al, 2015). The current study showed conflicting results for symmetry at the 4-cell stage, which may reflect differences in patient demographics, for example the patients in this study has a mean age of 31, where high euploid rates are to be expected.…”

“…The current study showed conflicting results for symmetry at the 4-cell stage, which may reflect differences in patient demographics, for example the patients in this study has a mean age of 31, where high euploid rates are to be expected. Further differences in the rates between previous studies and the current study may possibly be attributed to the number of chromosomes tested and whether ploidy was tested at the cleavage stage (Hardarson et al, 2001;Ziebe et al, 2003;Buehler et al, 2008) or blastocyst stage (Shenoy et al, 2015). As aneuploidy is not limited to certain chromosomes, when the number of chromosomes tested increases, the aneuploidy rate concurrently increases.…”

“…With an unequal portioning of cytoplasm between daughter cells, it is thought that there may be an unequal segregation of proteins, The Influence of Day 2 Blastomere Symmetry on Blastocyst Grade and Ploidy Status to quantify using measuring tools present within time-lapse monitoring software, where symmetry at the 2-cell stage has been incorporated into a known implantation data (KIDscore) algorithm during selection for Day 3 transfer (Basile et al, 2015). Embryos with asymmetric blastomeres have been shown to have higher rates of aneuploidy at the cleavage stage compared to embryos with evenly sized blastomeres (Hardarson et al, 2001;Ziebe et al, 2003;Buehler et al, 2008;Shenoy et al, 2015). It has been shown, however, that embryos with asymmetric blastomeres that progress to the blastocyst stage may have a comparatively reduced rate of aneuploidy, which could be due to a higher rate of cleavage stage arrest for aneuploid embryos or the speculation that embryos may be able to exclude aneuploid cells arising from mitotic division to 'selfcorrect' during blastocyst progression (Barbash-Hazan et al, 2009;Bolton et al, 2016).…”

“…It has been shown, however, that embryos with asymmetric blastomeres that progress to the blastocyst stage may have a comparatively reduced rate of aneuploidy, which could be due to a higher rate of cleavage stage arrest for aneuploid embryos or the speculation that embryos may be able to exclude aneuploid cells arising from mitotic division to 'selfcorrect' during blastocyst progression (Barbash-Hazan et al, 2009;Bolton et al, 2016). Conversely, not all studies provide evidence for this (Shenoy et al, 2015).…”