Embryo banking refers to a process called cryopreservation (freezing) to preserve embryos for future pregnancies for In Vitro Fertilization, for women wishing to preserve eggs for later in life, or for those about to undergo cancer treatments.
In freezing eggs and embryos, the Northeastern Ohio Fertility Center relies on an advanced freezing method, called Vitrification, that produces a higher rate of survival of frozen embryos than the traditional slow freezing technique. The higher rate of embryonic survival of frozen embryos in turn leads to higher pregnancy rates.
Vitrification allows for the preservation of unfertilized eggs. Prior to vitrification technology, very few eggs frozen with slow freezing techniques survived the freezing and thawing process and fewer still resulted in successful pregnancies. Vitrification technology allows unfertilized eggs to be stored or preserved for later use, with extremely high chances of success.
The preservation process
Healthy eggs are harvested from the ovaries and then fertilized with selected sperm in a laboratory. The resulting embryos are then frozen – or “banked” – for storage.
Embryos are frozen from one to six days after egg retrieval. Eggs, however, are frozen on the day of retrieval, and may remain in long-term storage until patients are ready to attempt embryo transfer and pregnancy. It should also be noted that men have an easier time with fertility preservation than women, because sperm is easier to obtain and freeze than eggs.
Some medical treatments, such as chemotherapy or radiation, can result in infertility for either men or women. Sperm or egg preservation should take place before such treatments begin.
For an excellent resource on this topic, see this reference from ASCO:
American Society of Clinical Oncology Recommendations on Fertility Preservation in People Treated for Cancer