Frozen Egg Transfer
Canberra Fertility Centre has been freezing
embryos since 1985, and the subsequent transfer of these
has resulted in the birth of many healthy babies. There is no increase of
abnormalities in children born from frozen embryos, than those from ‘fresh’ embryos. Embryos can be frozen after
24, 48 or 72 hours in culture and also at blastocyst stage. Consent forms
are signed relating to the “ownership” of the embryos in the
event of death/divorce etc and any disputes are directed to the Commissioner
of Health.
Management of the FET Treatment Cycle
You need to contact your
specialist gynaecologist to organise a cycle plan to be sent to the Canberra
Fertility Centre for your FET cycle. They may require you to have an appointment
with them to discuss this plan prior to commencing. You will also need to
make a booking for an FET cycle, so please check with the Nurse Coordinator
in advance. Please telephone the Canberra Fertility Centre approximately
a fortnight before your cycle to arrange a time to sign consent forms, as
we will not thaw any of your embryos without your written consent. One of
these consents must be signed for each transfer cycle. It is also necessary
for you to pay the appropriate prepayment before you begin your FET cycle.
The frozen embryo transfer cycle is relatively non-invasive compared to an oocyte retrieval cycle. The embryos can be replaced either in a natural cycle or in a controlled cycle depending on whether we can easily monitor the time of natural ovulation. We aim to transfer the embryos into your uterus at the correct time in relation to ovulation and the thickness of the lining of your uterus (endometrium).
In a “natural” FET cycle (where no medications are used before the embryo transfer), the cycle is tracked for ovulation using blood tests to monitor the hormone levels. As ovulation draws near an ultrasound will be requested to measure the thickness and maturity of the endometrium. If this is suitable, the embryo transfer will be performed 2–3 days after ovulation.
In a “controlled” FET cycle, Progynova (oestrogen) tablets are administered in order to prepare the endometrium for implantation. The development of the endometrium is monitored by ultrasound scanning (approximately 1–2 scans). The first ultrasound is usually performed on day 10-12. When the endometrium is thick enough and of the right maturity, the embryos will be thawed for transfer. Progesterone pessaries are used in conjunction with Progynova to maintain the endometrium, and these medications may need to be continued often for the first trimester of a pregnancy.
Thawing your embryos
The embryologist will thaw your embryos
so that the age of the embryos corresponds to the maturity of your uterine
lining. The exact timing will depend upon the stage at which the embryos
were frozen. You are asked to ring the day before your embryo transfer to
check the time that the procedure is booked for. Not all embryos survive
the freezing, storage and thawing process. You will be notified by the Nurse
Coordinator/Specialist if there is a problem.
Embryo transfer procedure
The embryo transfer procedure and
follow-up tests are the same as for IVF embryo transfer, described previously.
The success rate of an FET Cycle
The success rate using frozen
embryos is 20%. The pregnancy rate will depend on the number and quality
of embryos transferred, your age and your cause of infertility.
If you decide you no longer wish to have your frozen embryos kept for yourselves you have the choice of donating them or disposing them. A combination of these choices is also available. If you have not used all your embryos after 12 months then you will be contracted to confirm your intentions. You will then be contacted every 6 months for reconfirmation of intentions, and an invoice will will also be sent for continuing storage at this time.
