How Embryo Freezing Works

During In Vitro Fertilization (IVF), numerous embryos are produced, which then are sent for embryo freezing. IVF is a popular treatment for infertility that often is undertaken when all other procedures for assisted reproduction have failed. In this treatment, the egg is fertilized by the sperm outside the womb. The process involves regulating the ovulatory process hormonally in order to retrieve the ova (egg) from a woman’s ovaries, which are then fertilized by the sperm in a fluid medium.

Most IVF’s are planned so that the woman super-ovulates, in other words produce several eggs (ova). Normally not all the embryos produced as a result of super-ovulation are transferred for implantation, and hence you are left with spare or supernumerary embryos. Before embryo freezing came into practice, the extra embryos either were discarded or were used for research. Embryo Freezing is way of preserving the embryos to be used in the future and is also known as Embryo Cyroprservation.

How It Is Performed

After the embryos are assessed and graded, good quality embryos are considered for freezing at the early cleaved stage - the pronucleate (one cell) stage or the blastocyst stage (5 to 7 days post fertilization). Depending on the number of embryos that are to be transferred, the remaining embryos are clubbed in batches and then mixed with a cyroprotectant fluid. Two types of cryoprotectant fluids are used for this purpose, namely propanediol (permeating) and extracellular (non-permeating). The chief function of the cryoprotectant fluid is to lower the freezing point to prohibit the formation of intracellular ice. The other purpose is to prevent embryo damage during the freezing process by protecting the cells as they transform from one state to the other. This is possible since the cryoprotectant replaces the water contained in the cell preventing the formation of ice crystals.

The mixture of embryos and cyropotectant fluid is then transferred into straws made of plastic or glass ampoules and preserved in liquid nitrogen at a temperature of -320.8 degree Fahrenheit using sophisticated programmable devices. The plastic straws or glass ampoules are first sealed and labeled before being stored in canisters of liquid nitrogen. In order to add a level of security, some clinics lock the embryos in alarmed containers.

Preserving the embryos at temperatures as low as -320.8 degree Fahrenheit ensures no metabolic activity that is similar to a suspended state of animation. The embryos are safely preserved for as long as needed, usually up to a few years depending upon the regulation of the country. Some clinics have observed that pregnancy and birth-rates using frozen-thawed embryos match the rates of those using fresh embryo transfers.

Is Embryo Freezing Viable for You?

Embryo freezing is a viable option not only for women who wish to use the spare embryos for future, but also for women who stand a chance of developing ovarian hyperstimulation syndrome. The cost of transferring frozen-thawed embryos is much less compared to commencing a new hormonally controlled ovulation cycle to produce more embryos. In some special cases, the frozen embryos are donated through egg donation programs to infertile couples.

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