Comparison of Clinical Outcome after the Transfer of Cryopreserved and Fresh Embryos Originating from Conventional IVF and  ICSI

(J Reprod & Contracep. 2004,15(2):109-114.)

Su-ying Liu, Jin-lan Han, Zhu-di Lu, Ying Cao, Bin Teng, Yu Zheng, Jing-ming Yan.

Shanghai Ji-ai Genetics & IVF Institute, Shanghai 200011, China

Objectives  To evaluate the impact of cryopreservation on early cleavage stage (day 2) embryos by analyzing the outcome from frozen-thawed embryos in relation to the outcome from fresh embryos.

Methods  In this retrospective study, 1219 oocyte retrievals were performed, resulting in 977 fresh transfers. Embryos were cryopreserved in 68% retrievals. For couples who do not conceive after fresh embryo transfer, frozen thawed embryo transfers are subsequently performed. Embryo survival rate, implantation rates and clinical pregnancy rates per transfer from fresh and cryopreserved cycles were analyzed.

Results  From January 2002 to December 2002, a total of 628 thawing cycles in which 1876 embryos were thawed, the embryo survival rate was similar between the IVF and ICSI procedure (88.09 and 88.95% respectively). There was no significant difference in implantation rates either between the frozen and fresh IVF groups (19.19 and 21.07% respectively) or between the frozen and fresh ICSI groups (15.22 and 15.64% respectively). But there were significant differences either between frozen IVF and frozen ICSI groups (P<0.05) and between fresh IVF and fresh ICSI groups (P<0.01). The clinical pregnancy rates in the frozen and fresh IVF groups were 45.86 and 43.43% respectively(P>0.05). The clinical pregnancy rate of the frozen ICSI group was 42.07%, slightly higher than that of fresh ICSI (35.43%), but the difference was not significant (P>0.05). The clinical pregnancy rate between fresh IVF and fresh ICSI was significantly different (P <0.05).

Conclusions  The present study indicates that frozen-thawed embryos at early cleavage stage result in equivalent pregnancy rates as compared to fresh embryo..

Key words: cryopreservation; intracytoplasmic sperm injection; in-vitro fertilization