Culturing surplus poor-quality embryos to blastocyst stage have positive predictive value of clinical pregnancy rate

BACKGROUND Clinical reproductive centers produce large amounts of surplus poor-quality embryos annually, how to maximize the use of these embryos, and which of them have the potential to develop into blastocyst stage and influencing factors were lack of systematic research. OBJECTIVE To investigate the fate of surplus poor-quality embryos which were cultured to obtain blastocyst, determine the factors which may influence the blastulation, and discuss their application in predicting of the pregnancy outcomes. MATERIALS AND METHODS Day 3 (D3) after embryo transfer and freezing, surplus poor-quality embryos from IVF/ICSI cycles were cultured to blastocyst by the sequential method, then the blastulation outcomes were observed. Focusing on the blastulation rate of those embryos with different number cells and different embryonic grade; and last the relationship between the pregnancy outcomes of remained poor-quality embryos with successful blastulation or failed blastulation groups were studied. RESULTS Of 127 patients with 569 poor-quality in vitro cultured embryos, there were formation of 248 blastocysts from 91 patients (43.59%), which lead to development of 138 high-quality blastocysts (24.25%). With the increase in cells number of D 3 blastomeres, the blastulation rate gradually increased, that, 7-cell blastomeres blastulation rate was the highest (70.59%), and 8-cell blastomeres is a little below (70.37%); while the embryonic levels and blastulation rate did not show this positive relationship. The clinical pregnancy rate and implantation rate of those who had successful blastulation (67.03% and 42.39%) were higher than of those who failed to develop to blastocyst (p=0.039). CONCLUSION Day 3 poor-quality embryos with successful blastulation or with failed blastulation had predictive value on pregnancy outcomes. For embryo transfer 7-8 cells grade III-IV embryo is better than 4-5 cells grade I-II embryo, in case of lack good-quality embryos.