Embryo Cryopreservation is the process by which the surplus embryos from an IVF or ICSI cycle may be stored or frozen, for use at a later date.

Embryos can be frozen at a number of their developmental different stages – up to and including blastocyst stage. The Embryologist selects the embryos suitable for freezing. The embryos are then introduced into special culture media, called cryoprotectant, to help protect them during the freezing and storage process. The embryos are then frozen using a computerised embryo freezer.

Once frozen, the embryos are contained within appropriately labelled sterile straws. These straws are then securely stored in a locked storage vessel immersed in liquid nitrogen ( - 196 C). Embryos can be safely stored like this for up to 5 years.

Embryo Thawing is the process by which frozen embryos are thawed with a view to replacing the most suitable into the woman’s uterus. The freezing and thawing of embryos allows patients use surplus embryos from previous cycles.

During thawing, the frozen embryos are warmed in a controlled manner. Once thawed the embryos are introduced back into embryo culture. The embryos are thawed the day before the embryo transfer in order that the embryo’s development can be monitored. Not all embryos survive the freeze/thaw process.

Our Fertility Specialist performs the embryo transfer procedure. The selected embryos are introduced, through a fine catheter, into the woman’s uterus. Typically 2-3 embryos are transferred, depending on the patient’s circumstances. The embryo transfer procedure takes no more than half an hour and few women experience any discomfort.

Again, the spare embryos are then assessed in terms of their suitability to be re-frozen for use, by the couple, in future cycles.

Worldwide, the success rates for frozen-thawed embryos are lower than those for fresh embryo transfers.

Vitrification

Having the ability to preserve embryos is important service to our patients. Fertility units, worldwide, have used the same "freezing" technique for the last 25 years - with little modification.

One of the major huddles of "freezing" is that ice crystal formation is VERY damaging to embryos - this hurdle had never really been overcome. This is one of the reasons that, even the most capable IVF Units, rarely achieve that same results with frozen embryos as they were getting with fresh embryos.

Vitrification works on a completely different principle for cryo-storing embryos. Vitrification addresses the problem of ice crytal formation and allows for a reliable and successful cryopreservation of your embryo(s). Vitrification is a "glass like" state in which the embryo is suspended among high concentrations of cryoprotectants in liquid nitrogen.

The embryo survival rates are fanatastic and this has led to our "frozen" embryo pregnancy rates being almost equal to those of our fresh embryo transfers.