Long-term cryostorage does not adversely affect the outcome of oocyte thawing cycles

Abstract

This multi-centre study evaluated systematically the influence of the duration of cryostorage on the outcome of thawing cycles when using slow-frozen oocytes. The thawing cycles were retrospectively divided into three main groups based on cryostorage duration: group A, 1-3 months; group B, 4-6 months; and group C, 7-48 months. Group C was subsequently divided into three subgroups: group C1, 7-9 months; group C2, 10-12 months; and group C3, 13-48 months. Main outcome measures observed were oocyte survival after thawing, fertilization, cleavage; embryo quality and development, implantation, and birth. No significant differences in main outcome measures were observed between all the groups studied. In conclusion, human oocytes can be safely cryostored for several years. This finding could encourage the wider use of oocyte cryopreservation as a clinical procedure in assisted reproduction.

Implantation rates of embryos generated from slow cooled human oocytes from young women are comparable to those of fresh and frozen embryos from the same age group

“…In some of the above studies only oocytes with optimal morphology were cryopreserved [37,38] which is not the case in the present study.…”

Oocyte vitrification/storage/handling/transportation/warming, effect on survival and clinical results in donation programmes

“…Cryopreserved reproductive cells can remain stored for years (9,10) and transported between authorized AR centres. It has been demonstrated that frozen spermatozoa, oocytes, and embryos perform as well as their fresh counterparts (4,11,12); this is the main reason why frozen gametes are widely used for human heterologous insemination techniques.…”

Live birth after 6 years of oocyte vitrification in a survivor with breast cancer

“…One study evaluated oocytes up to 48 months and did not find any differences of survival, fertilization, cleavage, embryo quality, implantation and live-birth rates compared with earlier thaws. However, oocyte vitrification was performed for non-medical purposes [16]. For women with cancer, at the reproductive age, oocyte cryopreservation is advisable.…”