Clinical value of extended culture to blastocyst stage of surplus embryos in in vitro fertilization treatment cycles

Objective To investigate the developmental potential of surplus embryos after embryo transfer or freezing at day 3.Methods The surplus embryos were extended culture to blastocyst to observe the blastocyst development rate and blastocyst quality,and also the relationship between blastocyst formation and the pregnancy result was analyzed.Results In 115 IVF/ICSI-ET cycles,a total of 603 surplus embryos were extended culture to blastocyst,formed 222 blastulas(36.82%) among which 49(8.13%) were high-quality blastulas;53 frozen blastocysts(8.79%) were obtained from 36 cycles(31.30%);4 of 12 FET cycles achieved clinical pregnancy by transferring the frozen blastocysts formed of surplus embryos.≥6 blastomeres embryos,2PN embryos had a significant higher blastocyst development rate than other groups(P0.05);the blastocyst group had a significant higher clinical pregnancy rate than the group without blastocyst development(P0.05).Conclusion It had a limited value of morphological assessment at day 3 to predict the embryo developmental potential;It is a feasible method for increasing the number of available embryos in treatment cycles by blastocyst culture to select the potential embryos;The blastocyst development of surplus embryos could predict the pregnancy result.