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The facts about: Frozen Embryo Transfer
Generally speaking, success rates with a frozen embryo transfer are slightly lower than
IVF. The reason for this is that the best embryos are usually transferred during the IVF
cycle.
If the remaining frozen embryos are of the same quality as those transferred, then
success rates are likely to be the same. Approximately 75% of the frozen embryos will
survive the thaw process. Usually, the higher the embryo quality when it is frozen, the
higher the likelihood that it will survive the thaw process. Because not all embryos will
survive the thaw process, it may be necessary to thaw more embryos to achieve the
desired number of embryos to transfer.
Once you are ready to begin this cycle, it is important to contact your Nurse Coordinator
to ensure all consents, Medicare forms etc are completed prior to commencing a cycle.
Contacting your Nurse Coordinator can also ensure that you understand instructions
during this cycle. A treatment cycle in which frozen embryos are thawed and transferred
can be undertaken in two different ways:
1. Natural cycle, and
2. Hormone Replacement Therapy cycle.
Natural Cycle (FET)
In this method, ovulation takes place naturally and the embryos are transferred when
the uterus is naturally ready to accept embryos. Monitoring may commence 2 to 4 days
before estimated ovulation. Blood tests may be conducted to measure hormones
(oestrogen, luteinising hormoneand progesterone) until one day after ovulation.
Ultrasound is the preferredmethod of monitoring the size of the follicle and thickness of
the lining of the uterus (endometrium).
Hormone Replacement Therapy (FET)
Alternatively, Hormone Replacement Therapy (HRT) can be used to prepare the uterus
to accept embryos. The two female hormones - oestrogen and progesterone - act on the
lining of the womb to prepare it for implantation of an embryo or embryos. An
ultrasound scan to measure the thickness of the lining of the uterus will be performed
on day 10-12. If the endometrium is the right thickness, you will continue to take
oestrogen - and will be advised when to commence progesterone. Commencing
progesterone synchronises the uterus with the age of the embryos, so that day 3
embryos will be transferred into a ‘day 3’ uterus or day 5 embryos in a ‘day 5 uterus’.
Dr Terry Sheahan | Patient Information
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Progesterone is taken in the form of a vaginal pessary or gel. It is important that you do
not cease taking the oestrogen medication when you commence progesterone. All
patients on HRT therapy continue to use progesterone pessaries and oestrogen tablets
until the day of the pregnancy test. If the pregnancy test is positive, the above
medication will continue throughout most of the first trimester.
Oestrogen
Oestrogen is a hormone produced by the ovary that builds the uterine lining in the first
two weeks of the menstrual cycle and continues to be produced throughout the
pregnancy. Oestrogen medication is taken in tablet form. Dr Sheahan will determine
which oestrogen medication is best for you, however the common tablet prescribed
is progynova. Side Effects can include nausea, bloating, breast tenderness, headache
and increased vaginal discharge.
Consent to Thawing
Before the laboratory can thaw any of your embryos, you and your partner must sign
the Consent Form for embryo thawing.
Thawing your Embryos
The laboratory will thaw your embryos so that the stage of the embryo development
corresponds to your menstrual cycle. The exact timing will depend upon the stage at
which the embryos were frozen. Not all embryos survive the freezing, storage and
thawing process. On the morning of your embryo transfer, the laboratory will assess
your embryos to see if they are suitable for transfer. If they are, then the embryo
transfer can proceed.
The Embryo Transfer
For this procedure a fine tube (catheter) is passed through the cervix and the embryo(s)
are injected high into the uterus in a minute amount of culture medium. This technique
does not normally require sedation and is usually pain-free. The transfer will be made
easier if you have an empty bladder when you attend for this procedure.
After the Embryo Transfer
Controlled (HRT) cycle
It is important that you continue your oestrogen and progesterone medication as
prescribed by your fertility specialist until advised to cease.
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07 3353 3100
Natural cycles
You may be prescribed 2 hCG injections to administer on specific days following
your embryo transfer or commence on progesterone pessaries to support the lining
of the uterus.
A pregnancy blood test is ordered by your specialist for 14-16 days after your embryo
transfer to determine whether you are pregnant. If you are using hCG injections and you
do your pregnancy test earlier than advised, a ‘false positive’ may occur because of the
pregnancy hormone in the injection. It is important to always wait until the advised date
of testing unless your fertility specialist advises otherwise. Bleeding or spotting before
the pregnancy test may not be a period so it is important to continue on all medication
until advised to cease by your IVF nurse or clinician.
Problems

Cancellation of Frozen Embryo Transfer cycle
Occasionally there are difficulties in establishing the time of ovulation and the
treatment cycle may need to be cancelled.

No Embryos Survive Freeze/Thawing
It is rare for all embryos to survive freeze/ thawing, however usually at least one
survives in good condition. In around 5% of cases none of the embryos survive
and the transfer must be cancelled.

Pregnancy Loss
The rate of pregnancy loss due to miscarriage or ectopic pregnancy is similar to
that for IVF-ET. There is no evidence from either human or animal research that
the freezing and thawing of embryos increases the incidence of congenital
abnormalities.
SOURCE: “Life Fertility Clinic" www.lifefertility.com.au
Dr Terry Sheahan | Patient Information
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