Cryopreservation refers to the storage of a living organism at ultra-low temperatures such that it can be revived and restored to the same living state as before it was stored.
Embryo Cryopreservation (Freezing)
Embryo cryopreservation (the process of freezing, storing, and thawing embryos) can enhance pregnancy rates by allowing excess embryos not replaced in a fresh embryo transfer to be stored for future use.
Embryo freezing may also be performed when a fresh embryo transfer is not performed for any of the following reasons:
- Risk of ovarian hyperstimulation syndrome (OHSS),
- Poor quality endometrium (a thin uterine lining),
- Intermenstrual bleeding,
- Planned “banking” cycle in which the patient elects to store all embryos,
- Extremely difficult embryo transfer.
Embryos are placed into straws or vials containing anti-freeze or cryoprotectant solutions. These are transferred to a programmable biological freezer which is used to achieve a controlled slow rate of cooling. During cooling, cells dehydrate and as the temperature is reduced, more ice forms, and water is removed gradually from the cells. Slow cooling is continued to ~ -35°C at which point embryos are rapidly cooled by plunging into liquid nitrogen (-196°C). Embryos are kept in storage tanks of liquid nitrogen until thawing is performed.
Vitrification
Vitrification in IVF can allow the freezing of spare embryos with better post-thaw survival rates and higher pregnancy and live birth rates from the frozen embryo transfer cycles. We started vitrification of embryos in our IVF lab and have seen excellent post-thaw embryo survival and high pregnancy rates after frozen embryo transfer procedures.
Semen Cryopreservation
Semen freezing is useful for men who find it difficult to ejaculate on demand which may result in their inability to produce a sample on the day of egg collection.
Sperm from two sources can be frozen: from ejaculates or from fluid extracted in the operating room during surgical procedures (vasal, epididymal, and testicular sperm specimens). The sperm is usually frozen for a period of one year; at that time, future arrangements are discussed. It is generally believed that sperm that have been through the freeze-thaw process are no more likely to result in birth defects than freshly ejaculated sperm.
Looking for personalised advice? Our consultants at Ridge IVF, Delhi can review your reports and explain your options in one visit.
Related articles
Frequently asked questions
How long can frozen embryos or eggs be stored?
Vitrified embryos and eggs remain stable for many years. Storage limits are set under the ART (Regulation) Act and Rules, and your consent form records how long they are kept and what happens afterwards.
Does egg freezing reduce natural fertility later?
No. Stimulation uses eggs from that month's group of follicles that would otherwise be lost, so it does not bring menopause forward. Egg freezing guide.
How many semen samples should be frozen before chemotherapy?
Two or three samples give a useful reserve, but if treatment must start urgently even one sample is worth freezing. Oncofertility preservation.
The information on this website is for general education and does not replace a consultation. Treatment plans and outcomes differ from person to person; no treatment can guarantee pregnancy or a live birth.
