Freezing – Vitrification

We use a process called ‘vitrification’ to freeze the eggs and embryos. Vitrification involves rapid cooling helping to prevent the formation of ice crystals. This helps to preserve the quality of the cells and improves the chances of success when they are thawed for later use.

Embryo vitrification

This is now a well-established procedure. It allows us to freeze surplus good quality embryos for future use. Embryos can be frozen at various stages, depending on how they develop. The decision of when to store embryos will depend on the number of good quality embryos available in the cycle.

Vitrification has improved the outcomes of embryo freezing. It is now very reliable practice, yielding comparable success rates to those achieved with the transfer of fresh embryos.

Occasionally, it may be decided to vitrify all of the embryos created in a cycle, and postpone the embryo transfer till a later date. This is carried out to help prevent the development of ovarian hyperstimulation syndrome (OHSS) or to await surgery.

Egg vitrification

We can use the vitrification procedure to successfully freeze eggs immediately after the collection procedure. This is important for women who would like to store eggs before undergoing chemo- or radiotherapy, or other treatments that might affect their fertility in the future.

We also store eggs for women who are not ready to start a family, but who recognise the importance of storing eggs whilst they are younger. Eggs collected and stored earlier in life are said to be of a better quality than in those women who are of an older age bracket.

Learn more about fertility preservation here.

Egg freezing also plays an important role in the operation of the Egg Donation programme. Donated eggs are frozen and stored in the Egg Bank. Learn more about our egg-sharing program here.

Sperm freezing

You may need to store sperm for fertility preservation prior to certain medical procedures, or in the course of a fertility treatment cycle:

  • Prior to chemo- or radiotherapy
  • Prior to vasectomy
  • Prior to any surgery that may result in impaired fertility
  • Prior to sex reassignment
  • Prior to a fertility treatment cycle after sperm has been retrieved via surgery
  • Prior to a fertility treatment cycle as a ‘back-up’ sample for the day of treatment

Sperm that is donated for other couples or individuals to use, is vitrified and quarantined, while all the appropriate donor screening tests are undertaken. The sperm is not released for use until all the test results have come back and are deemed clear.


To learn more about any of our fertility treatment options and costs, or to book an appointment with one of our consultants, please contact us.