Impact of blastomere survival on implantation rate of frozen-thawed embryo transfer

AIM: To study the impact of blastomere survival on the implantation rate of frozen-thawed embryo transfer FET.METHODS:We conducted a retrospective analysis of 134 FET cycles from September 2003 to September 2005.According to blastomere survival rates,all FET cycles were categorized into 3 groups: group A(n=46) included cycles in which all their original blastomeres remained intact;group B(n=65) refered to mixed transfer of fully intact embryos together with partially damaged ones;group Cn=23 was composed of all transferred embryos with partially damaged blastomere.RESULTS: Out of 642 thawed embryos,455 survived,survival rate being 70.8%.The pregnancy rate was 24.6% per FET cycle.The pregnancy rate and the implantation rate of group A,B,and C were respectively 34.7% and 18.5%,23.1% and 8.2%,8.7% and (3.8%).There was a significantly higher implantation rate in group A than in group C(P0.05).Along with the increase of intact embryos in FET cycles(0,1,2,3),there was a significant increase in the pregnancy rate(8.7%,15.0%,31.4%,38.9%) and the implantation rate(3.8%,6.1%,16.2%,(18.5%,) P0.05).CONCLUSION:Blastomere survival status is a most important factor influencing the implantation rate of frozen-thawed embryo transfer.