研究開発・学会発表

【Objective】

This study explores the relationship between abnormal cleavage such as direct cleavage from 1-3 cells and 2-5 cells, of developing embryos and its correlation to blastocyst formation.

【Design】

A clinical retrospective study

【Methods and Materials】

Embryo development was recorded and analyzed using Embryoscope, Unisense Fertilitech, Denmark. All morphokinetic observations were made with special attention to the time at which the pronuclei disappears, first and second cleavage times. 34 couples (maternal age≦38) underwent ICSI (n=263), of which 45 cycles led to an embryo transfer between December 2012 and September 2013. All transfers were frozen cycles and embryos were transferred at either cleavage or blastocyst stages.

【Results】

Of 263 cases, 194 embryos were kept in continuous culture till Day 5. Thirteen of these embryos had an abnormal division from 1-3 cells and another 11 embryos divided directly from 2-5 cells. Whereas embryos dividing from 1-3 cells directly could not form any blastocysts, three embryos with abnormal cell division from 2-5 cells successfully developed into blastocysts. One of three however, led to a successful fetal heart beat.

【Conclusion】

These results indicated that good quality blastocysts developed slightly faster than others; thereby supporting the fact that the divisions must take place during a narrow window to maintain the viability of the embryo.Focusing on the first cleavage times, our study concludes that embryos divided from one to two cells had approximately 35% increased chance of successfully growing into a blastocyst than those that cleaved from one to 3 cells, therefore recognizing it as an imperative marker. Lastly, our results show that abnormally dividing embryos can potentially result in a positive pregnancy suggesting that if the embryo does develop into blastocyst after the 2-5 cells, there may be a chance to applying transfer.