Embryo freezing and thawing



Standard cycles


After embryo transfer any remaining good quality embryos can be frozen and stored for later use through a process known as cryopreservation. Embryo freezing is an essential part of a comprehensive IVF service. This allows good quality embryos to be placed into the uterus at the optimal time and allows full use of all good quality embryos. Around half of our patients have embryos available for freezing.

At Westmead Fertility Centre (WFC), we successfully freeze embryos on Day 1, Day 2, Day 3 and Day 5. If pregnancy does not occur in the IVF cycle, your frozen embryos may be thawed and transferred in a later cycle; this is called a frozen embryo transfer (FET).

Frozen embryos may be thawed and transferred at the appropriate time in any subsequent cycle, even several years later. If your menstrual cycles are normally regular, medication to stimulate the ovaries is not required in a cycle in which thawed embryos are replaced. It is only necessary to ‘track’ that cycle for a few days prior to the expected day of ovulation, to find the optimal time to transfer the embryos.


‘Freeze ALL’ cycles


Sometimes when patients are undergoing an egg collection cycle, it is discovered that the uterus lining (endometrium) may not be optimal for a ‘fresh transfer’, i.e.using the embryos created in that cycle. In this circumstances, we use our recently introduced and highly successful Next Generation Freezing method in which we freeze ALL embryos. More than 95% of embryos frozen using this method will survive and cleave after thawing at a later date and a single blastocyst will be transferred.


Risks in transferring frozen embryos


You should be aware that:

  • not all embryos are suitable for freezing
  • not all embryos survive the freezing and thawing process.

Pregnancy from frozen thawed embryos depends on the initial embryo survival as well as their ability to grow and develop.

Attend a free information seminar
Westmead ButtonWestmead Doctor, IVF clinic
When: Wednesday 28 November 2018
Time: 6pm
Where: Westmead Hospital