Frozen (thawed) embryo transfer
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The embryo storage facility |
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After thawing, the embryo quality is checked. |
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If a previous IVF attempt was unsuccessful, but you still have a number of embryos available in storage, then consequent treatment will be simpler.
The same is true if
donor embryos are the only solution for your fertility problem. In both cases it is not necessary to undergo the hormone stimulation phase in order to produce follicles, or to have a pick-up.
Ever since the new legislation regarding medically assisted reproduction came into force in 2007, you are obliged to use stock of your frozen embryos first in every subsequent IV attempt before a new attempt with fresh material can be undertaken.
Although with thawed embryos the chance of a successful pregnancy is smaller than with fresh embryos, FRETs (frozen embryo transfers) are extra chances of fulfilling your wish to have a child. If you are a Belgian patient and a member of the national health service, only 6 attempts (with fresh material) will be reimbursed. Transfers of thawed embryos donÕt count: they are considered extra attempts.
Synchronised to the natural cycle
Reminder: day one of your menstrual cycle is the day upon which your menstrual bleeding begins. |
Whenever possible, the embryo transfer is planned to take place within the natural cycle of the woman. During the course of the treatment, the woman will be under the guidance of the Daily Monitoring Department.
- As of a few days before the natural ovulation, blood tests will be commenced.
- Sometimes the ovaries are lightly stimulated, to give extra support to the natural cycle:
- either you will take anti-oestrogen from day three up to and including day seven, in the form of capsules at a dosage of two capsules a day (see clomifeen citrate);
- or you will self administer injections of hMG or rec-FSH for a period of five days (or have your partner administer them).
possible side effects are restricted in the case of anti-oestrogen to a bloated feeling in the abdomen, hot flushes and occasionally, flashing lights before the eyes. the injections can be accompanied by mild abdominal pain.
- If the blood results indicate that the moment of ovulation is approaching, an ultrasound scan will be performed in order to determine the stage of development of the endometrium (the lining of the womb).
According to Belgian law, a maximum of two embryos may be replaced, depending on your age. See financial for further details. |
- As soon as this seems to be of an adequate thickness, either ovulation will be triggered with an injection of hCG, or the natural peaking of LH will be awaited in order to be able to plan the thawing and transfer of the embryos.
- The moment of the transfer will be planned according to ovulation and you will be informed by the DM.
- To influence the implantation of the embryo in the uterus, you will be required to insert vaginal progesterone pessaries three times a day for a few weeks as of the moment of ovulation.
Artificial cycleIt is sometimes necessary to completely replace the natural cycle with an artificial one:
- if there is no natural cycle, for example because the ovaries have been removed, your uterus will be prepared for pregnancy by the administration of oestrogen. This will be administered orally, starting at least two weeks before the transfer;
- if there is a natural cycle, but it is faulty, it will be synchronized via the administration of GnRH-analogs. After three weeks, the GnRH analogs will be combined with the administration of oestrogen. the transfer can take place two weeks later at the earliest.
- A few days beforehand you will be required to administer progesterone in the form of vaginal pessaries.
Because ovulation does not need to be taken into account, an artificial cycle is very effective and accurate. The transfer can be planned well in advance. It is also very suitable for couples using donor egg cells.
Blood tests after the transfer
If the transfer with frozen embryos is synchronized into your natural cycle, the same blood tests are performed as with fresh embryos:
- a blood sample for the evaluation of the progesterone and hCG levels is taken on the 15th day after embryo transfer;
- if the transfer does not result in pregnancy, an additional blood test will be performed on the third day of the menstruation. The exact time and date of the onset of menstruation must be given on the form requesting the blood test. Please take care not to let your natural disappointment at the onset of a period make you forget this final blood sample.