Background: Freezing of embryos and gametes is considered one of the corner stones of
ART. Its application increases both IVF safety and efficiency.
Aim and objectives: the aim of the present study is to compare cleaved embryo and
blastocyst freezing to determine the optimal time for embryo cryopreservation,
Subjects and methods: A randomized clinical trial, it was involved 300 cases of infertile
patients who will undergo ICSI cycles and embryo freezing at the assisted reproduction
unit, Qena University hospital, South Valley University, Egypt after complete infertility
evaluation. Population was divided into two groups: Group 1 (n =150), underwent embryo
freezing at day 3 then will undergo FET (Cleaved embryo). Group 2 (n =150), will
underwent embryo freezing at day 5 then will undergo FET (Blastocyst) The duration of
the study had been from 6 to 12 months,
Results: the results revealed that there is high significant difference between the studied
groups as regard Total number of survival more survival was observed in blastocyst
group, while there is no significant difference between the studied groups as regard
completed transfer.
Conclusion: The maintenance of embryo culture until day 5 may be a more sensible
approach for the correct identification of best quality embryos with the highest probability
of success for both transfer and freezing.