Freeze-storage of embryos, known as cryopreservation, involves storing any surplus healthy embryos for future transfer.
The advantage of embryo freezing is that it increases the chance of a pregnancy per stimulation cycle and egg pick up without increasing the multiple pregnancy rate.
At Melbourne IVF about half of our births, over many years, have come from the transfer of frozen/thawed embryos. A thaw transfer is a much less complex and much less costly procedure than an egg retrieval cycle, yet these relatively easy cycles boost the birth rate significantly.
It is important to note that not all embryos survive the freezing or thawing process. We only transfer those that will offer you a chance of pregnancy.
Frozen embryo cycles can be undertaken either as:
- natural thaw cycle; or using
- artificial thaw cycle
Please note the information below is a guide and your specific treatment plan will be individualised by your fertility specialist.
Natural Thaw Cycle - Frozen Embryo Transfer
During a Natural Thaw Cycle the embryo which was frozen on day 2 or 3, is thawed and replaced in the woman’s body in synchrony with her own cycle, two or three days after ovulation. A natural thaw cycle is undertaken if periods are regular and no ovulatory problems are present.
| Approx one week before period due |
Once you have made the decision to start treatment, the first step is to call the Patient Liaison Administration team prior to the first day of your period, to organise payment and collection of your medication, so you are ready to begin treatment without delay. |
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Day 1:
Call the nurses
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On the first day of your period (full flow of bleed), telephone the nurses who will review the doctor’s treatment recommendations – this is called Day 1. If you have not previously organised payment, you will need to speak with the Patient Liaison Administrators first in order to do so.
The nurses will ask you for your cycle lengths (the time from the commencement of a normal period until the first day of the next period). This is so they can calculate when you are likely to ovulate.
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| Day 10-12: |
Attend the clinic for an ultrasound scan around day 10 to 12 which should be just prior to ovulation, to look at follicle development. If a dominant follicle is not located during this scan, another scan appointment is made for several days time. If a dominant follicle is present, hormonal testing using urine testing (Seratec) or blood tests are used to detect the presence of Luteinizing Hormone (LH). |
| Day 10 to 16: |
Usually once blood tests begin they are performed every second day with urine testing performed daily in the morning. You will continue monitoring until a change in the LH level is detected. The LH surge signals the commencement of the ovulation process, and usually ovulation occurs the next day. |
| Day 18 (approx): |
Following ovulation, an Embryo Transfer procedure is organised for 2 days later. |
| Day 32 (approx) |
A pregnancy blood test is organised about 14 days after the transfer. |
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Artificial Thaw Cycle – Frozen Embryo Transfer
When an artificial cycle is used for a thaw cycle, the woman’s cycle is controlled by medications that contain the hormones produced during the normal menstrual cycle.
| Approx one week before period due |
Once you have made the decision to start treatment, the first step is to call the Patient Liaison Administration team prior to the first day of your period, to organise payment and collection of your medication, so you are ready to begin treatment without delay. |
| Day 1:
Call the nurses
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On the first day of your period (full flow of bleed), telephone the nurses who will review the doctor’s treatment recommendations and plan your cycle with you – this is called Day 1. If you have not previously organised payment, you will need to speak with the Patient Liaison Administrators first in order to do so.
The nurse will arrange for you to collect your prescription before you are required to start, if you already haven’t done so.
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| Day 5: |
On day 5 of your period, the nurses will instruct you to begin oestrogen tablets in the morning and night, or as directed by your fertility specialist, to allow the lining of the uterus to develop.
You will continue with this medication for approximately 7 days. An appointment for an ultrasound scan with your doctor will be required for day 12 of your cycle.
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| Day 12: |
On day 12 of your cycle attend an ultrasound scan appointment with your fertility specialist. The ultrasound will measure the lining of the uterus. Once it is determined that the lining of the uterus is thick enough (it should be at least 7mms in thickness), you are ready to start progesterone pessaries and the nurse will advise you on this. |
| Day 13 to 15: |
The progesterone is a hormone released after ovulation, which prepares the uterine lining for implantation. The progesterone pessaries are taken twice a day (morning and night) and are taken for two days prior to embryo transfer. Both the oestrogen tablets and the progesterone pessaries are continued up until the pregnancy test and should also be taken on the morning of the embryo transfer. It is important to note that we would not expect a period prior to the pregnancy test due to the medication you are taking. |
| Day 15: |
After two days of taking progesterone pessaries you will have attend the clinic for the embryo transfer. Thawing the embryos takes approximately 40 minutes and is done the day they are to be transferred or the day before planned transfer and cultured overnight. The embryo transfer is a procedure similar to a pap smear. |
| Day 29: |
The pessaries and the oestrogen are continued until pregnancy test, which is about 14 days after transfer. If you are pregnant the medication are continued for a further 4 to 6 weeks until the 8th or 10th week of pregnancy when the placenta takes over hormonal control of the pregnancy.
Should the pregnancy test be negative, both the tablets and the pessaries should be stoped as a period will not occur until you stop taking them (as the artificial hormones control the cycle).
It is important to call the nurses or your doctor should bleeding occur before your pregnancy test, or after a positive test, as this may indicate that hormone levels are insufficient or that the pregnancy needs further monitoring.
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