Cleavage anomalies in early human embryos and survival after prolonged culture in-vitro

This study examines the relationship between common morphological anomalies of cleaving embryos and their ability to form apparently normal blastocyst s in vitro. The impact of cleavage rate, fragmentation, and multinucleation on compaction, cavitation, along with inner cell mass and trophectoderm fo rmation has been assessed. The study population consisted of 102 patients w ho elected or were selected to have a day 5 embryo transfer, Clinical pregn ancy and implantation rates were 66.7 and 49% respectively, Slow and fast c leavage had a significant negative association with normal blastocyst forma tion. Only 13.8% (67/484) of embryos with <7 cells and 27.5% (25/91) of tho se with >9 cells on day 3 formed blastocysts with apparently normal morphol ogy, compared to 41.9% (252/602) with 7-9 cells on day 3 (P < 0,001), Fragm entation had a negative impact on normal blastocyst formation. Embryos with >15% fragmentation formed normal blastocysts at a significantly lower rate (46/279; 16.5%) than embryos with 0-15% fragmentation (311/935; 33.3%) (P < 0.001). Furthermore, the pattern of fragmentation was associated with bla stocyst formation, Type IV fragmentation led to a significant reduction in blastocyst formation (25/170 or 14.7%), compared to types I, II and III whi ch performed much better (38,6, 32.9 and 32.4% respectively), Only 15.9% (2 2/138) of embryos with one or more multinucleate cells on day 2 and/or 3 fo rmed normal blastocysts compared with 31.9% (335/1051) (P < 0.001) of those without multinucleation, Collectively, the data suggest that cleavage anom alies, some of which do not preclude development after short-term culture, may reduce the developmental competence of embryos after prolonged culture.