Prior to the use of embryo cryopreservation, any remaining embryos following an embryo transfer or a canceled cycle (as in the case with hyperstimulation syndrome prior to embryo transfer) were discarded. With the development of improved cryopreservation techniques, these additional embryos can be frozen for use at a later time. Cryopreservation allows for subsequent "frozen embryo transfers" (FET) and additional attempts at conception without having to undergo additional stimulation with gonadotropins. This improves the overall safety and cost of infertility treatment. Oocyte recipients and IVF patients almost always choose cryopreservation as a means of extending their attempt at achieving pregnancy The consent process for cryopreservation is separate from the IVF and donor cycle consents and should be completed (if desired) prior to the start of the cycle. The consent has unique requirements that the parent(s) must indicate their desires as to disposition of the embryos in the event of a divorce or death of one of the partners.
Survival of the embryos is not 100%, but the techniques are designed to maximize the survival of the embryos. Currently, embryos frozen at earlier stages tend to have a higher survival rate than embryos frozen at later stages (day 3 vs. day 6). Once the embryos are frozen they do not have a known shelf life. Pregnancies have been reported from embryos stored over 16 years. The embryos chances of resulting in a pregnancy are based on the patients age when they are frozen and not when they are transferred.
Another important concern is the safety of the techniques to the embryo and the potential future child. There have been many studies on the safety and long term effects of cryopreservation. Currently there is not any known risk associated with cryopreservation. Such studies are very difficult to conduct due to demographics of different countries, occurrence of abnormalities in the general population, and the number of years needed to make such assessments.
Our lab uses very strict techniques and labeling procedures to insure proper identification of embryos. The lab also uses a witness system and redundant paperwork to maintain strict protocols regarding identity and safety. [Click Here for More Information]