Frozen Embryo Transfer (FET) Procedure
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What is Frozen Embryo Transfer?
Frozen Embryo Transfer (also known as FET), is a procedure in which a cryopreserved embryo which has been created in an egg retrieval cycle is thawed and transferred to the woman’s uterus. The woman undergoes a standard IVF procedure, but instead of the embryos being transferred back into the uterus in the same cycle, they are frozen for use in a future cycle. A woman can use her own eggs or choose to use donor eggs, depending on her situation and medical conditions. This procedure is preferred as the woman can recover from her current IVF cycle and it also reduces the effect of desynchronisation.
Desynchronisation in IVF cycles
During a regular menstrual cycle, oestrogen levels naturally peak during ovulation and the ovaries start producing progesterone which triggers the development of endometrial lining of the uterus. For a pregnancy to take place, a fertilised egg needs to implant in this lining and grow. Since the body produces progesterone as a response to ovulation, in the right conditions, the lining develops at the right rate to nurture the fertilised egg. This synchronisation between the progesterone response and development of the lining is necessary for implantation.
However, during IVF treatment, as the ovaries are artificially stimulated, the peak in oestrogen ends up being more than natural and it leads to progesterone production which may be earlier than necessary. Thereby, the endometrial lining develops very quickly to support the embryo. If there is desynchronisation between the development of lining and implantation, the implantation may not happen successfully.
Frozen Embryo Transfer vs Fresh Embryo Transfer
While frozen embryo transfers are preferable, fresh embryo transfers also have their positive points. Your doctor will recommend what is best for you given your medical condition.
|Fresh Embryo Transfer||Frozen Embryo Transfer|
|Occurs in the same IVF cycle||Occurs in a different IVF cycle|
|Eggs are retrieved, fertilised in the lab, embryos are allowed to develop and are then transferred back into the woman’s uterus around 5 to 6 days after the retrieval||Here, on day 5 or 6, the embryos are frozen instead of being transferred back into her uterus|
|Preimplantation genetic testing may or may not be done||Preimplantation genetic testing can be performed on the embryos before they are frozen to screen for common chromosomal diseases|
|Recommended for younger patients when there is not a suspected chromosomal issue||Recommended for older patients|
|Success rate differs||Higher success rate|
What Are the Benefits Of Frozen Embryo Transfer?
Your doctor may recommend a frozen embryo transfer if you have medication conditions, lifestyle conditions or other concerns. Here are a few cases where one may need a frozen embryo transfer:
- Extra Embryos: An IVF may lead to more than one embryo, but it is safe to transfer only one or two at a time. If multiple embryos are transferred, it may lead to a high-risk pregnancy. To reduce this risk, a frozen embryo transfer is helpful, especially if you have a good prognosis. Even if the transfer isn’t successful, you will have embryos remaining after the cycle.
- Wanting more than one child: Cryopreserved embryos can remain on ice indefinitely. After a successful IVF induced pregnancy, if, in the future you decide to have one more child and give your baby a sibling, a frozen embryo transfer allows you to have that option as you have cryopreserved your embryos.
- Using genetic screening: Preimplantation Genetic Diagnosis (PGD) and Preimplantation Genetic Screening (PGS) are assisted reproductive technologies that screen embryos for specific genetic diseases or defects. This can be done via a biopsy, a few days after fertilisation or egg retrieval. If the genetic testing and biopsy takes more time the biopsied embryos can be cryopreserved. Once your doctor gets the test results, you can mutually decide which embryo can be transferred.
- Upon choosing an elective procedure: Research has shown that hormonal medication used for stimulating the ovaries during IVF treatment may not always create conducive environments for implantation in the uterus. A fresh transfer may therefore not lead to a viable and successful pregnancy. With a frozen embryo transfer, that isn’t the case and once the endometrial lining has been formed without the use of hormonal medication, the transfer can happen. However, if you do not ovulate naturally, the doctor may prescribe some hormonal medication to increase endometrial receptivity during the process of FET.
- High risk of Ovarian hyperstimulation syndrome (OHSS): This is a case where fertility medication may lead to loss of fertility or even death. If this appears to be high during a fresh embryo transfer, the procedure may be cancelled, and embryos will be cryopreserved. Once you have recovered from OHSS, a frozen embryo transfer cycle will be scheduled.
- Cancellation of fresh embryo transfer: A fresh embryo transfer can be cancelled due to other reasons such as having the flu, or some other illness that strikes you after the egg retrieval but before the transfer. Also, endometrial conditions may not look good during an ultrasound which may lead to the cancellation.
- Using a donor embryo: If you are using donor embryos, you will have to undergo frozen embryo transfer.
Steps In a Frozen Embryo Transfer
- Preliminary Consultation: A fertility expert will do a preliminary scan to evaluate your medical condition and then, based on the assessment, they will create a treatment plan to ensure a successful pregnancy
- Treatment Discussion: The doctor will then take you through the treatment plan and two weeks before the start of your menstrual cycle, you will be called to the fertility clinic to meet with the doctor and complete all formalities and go over the plan again
- Scans & Tests: This step requires you to take 2 or 3 monitoring scans that are usually placed days apart. During these appointments, the doctor may also suggest blood tests
- Embryo Transfer: The frozen embryo transfer procedure will take place and will usually be easy and quick
- Pregnancy Test: For the final step of the procedure, the doctor will call you in for a quick pregnancy test and share the results on the same day.
Cost Of Frozen Embryo Transfer
A frozen embryo transfer is much more beneficial than a fresh embryo transfer as desynchronisation can be avoided and lead to a successful pregnancy. The steps in a frozen embryo transfer are simple and it has multiple benefits too, especially for patients who have OHSS (Ovarian hyperstimulation syndrome) or other medical conditions.
This depends on the patient and their needs- you can do it after an unsuccessful IVF cycle, induce a second pregnancy or at a later stage if you don’t want a baby immediately.
While there is mild discomfort during a frozen embryo transfer, it won’t be very painful. Make sure you follow the doctor’s instructions and take your medication.
Yes, you can resume your regular activities after an FET. It is advisable to avoid strenuous activities like extreme exercises or lifting heavy objects.
First step towards infertility is correct diagnosis and NOT treatment.