- This process cools the sperm and embryos very slowly to sub zero temperatures.
- Cyropreservation is used to store semen and embryos for an indefinite period.
- It is typically effective if men face a possibility of sterilization due to vasectomy, prostate or testicular surgery, radiation or chemotherapy etc.
- At times semen is also frozen prior to IVF as back up, incase of difficulty in semen collection on the day of oocyte retrieval.
- Vitrification is one of the latest advancements in fertility treatment.
- The process refers to the freezing of eggs (also embryos) to store them for an indefinite period. Unlike sperms, unfertilized ova cannot be stored using the slow freezing technique.
- Rather, vitrification works by using higher concentrations of cryoprotectants that ensure much faster cooling rates, and without the formation of ice crystals.
- It is useful for women who face the possibility of sterilization in future.

Sperm freezing and storage
Sperm freezing and storage is the procedure whereby sperm cells are frozen to preserve them for future use. Sperm cells have been frozen and thawed successfully for more than 40 years. By using special technology and then keeping sperm in liquid nitrogen at minus 196C, it can be stored for many years while maintaining a reasonable quality
Who may benefit from sperm freezing?
- Men who work in high risk occupations, for example:
- Men in the military have frozen sperm and completed posthumous use consent forms before
- Deployment In case of their serious injury, or even death when on active service
- Where there is a family history of premature andropause, especially in the man’s father, uncles or paternal grandfather
- Men who are away from home for extended periods of time and whose wives or partners may require fertility treatment during their absence
- Any man whose sperm counts are declining and there is concern that he could become a zoospermic
Embryo Freezing
In a typical IVF or ICSI treatment cycle, the woman’s ovaries are stimulated to produce many eggs. Following fertilisation and embryo culture, the best embryos are selected for embryo transfer. For about 50% of couples, there will also be good embryos which are surplus to those required for embryo transfer. These embryos can be frozen at this point for future use.
Embryo freezing (cryopreservation) is a method of preserving the viability of embryos be carefully cooling them to very low temperatures (-196°C). This is carried out in the laboratory using specialised freezing equipment and the embryos can then be safely stored in liquid nitrogen for extended periods.
