IVF and Frozen Embryo Transfer (FET)

The process of building a family while generally desired is one that is not as straightforward as many think. In this article, the topic of discussion is frozen embryo transfer. Frozen embryo transfer preparation for couples may be filled with uncertainties and fear, especially for couples who have previously experienced IVF failures. However, IVF frozen embryo transfer has been proven to give a higher chance of live birth than a fresh IVF process, making the frozen transfer a very popular option for fertility specialists and couples who have experienced failures in their previous attempts at conception.

Frozen embryo transfer also requires the preparation of the uterus. This correct preparation is essential in increasing the chances of a successful live birth post-frozen embryo transfer.

What is frozen embryo transfer in IVF?

Frozen embryo transfer (FET) is made possible because previous IVF procedures produce additional embryos that couples choose to preserve by freezing. They do this for future attempts especially if the initial IVF cycle is unsuccessful or when they want more children. Simply put, a frozen embryo transfer is a type of IVF treatment where a cryopreserved embryo formed in a previous egg retrieval process is thawed and transferred into the uterus. 

On the day scheduled for the embryo transfer procedure, the embryos will be thawed and transferred to the uterus of the woman using a catheter. The process is less stressful and shorter because the embryo is from a previous cycle. Hence, all the steps that would have been necessary if the IVF process was started afresh are truncated. The uterus is specially prepared following menstruation by fertility specialists. They administer medications to the woman every three days for about two to three weeks which acts to thicken the lining of the woman’s uterus in preparation for the embryo transfer.

Types of frozen embryo transfer IVF cycles

There are two ways of preparing for frozen embryo transfer IVF cycles, they are:

• Hormonal support cycles – This is the more popular type with couples. In this type, estrogen and progesterone are administered to mimic the body’s cycle and thicken the lining of the uterus. This type is also preferred by clinics and fertility specialists because it helps in making the process more predictable. This is because the day of the embryo transfer will be correctly fixed and any problems can be corrected with the appropriate hormonal support.
• Natural support cycle – In this type, the timing of the frozen embryo transfer is estimated using the natural ovulation of the woman as a marker. However, an hCG shot will be administered to ensure that ovulation occurs, and progesterone will be administered for luteal phase support after the ovulation and transfer have occurred.

What are the reasons for choosing frozen embryo transfer?

Frozen embryo transfer may be suggested by a fertility specialist or doctor in any of the following circumstances:

There are extra embryos

Even though a typical IVF procedure results in more than one embryo, it is only safe to transfer one or two at a time. The transfer of multiple embryos may lead to an increase in the chances of triplets or quadruplets. This risk is reduced by selecting the best embryo for an elective single embryo transfer. This results in many embryos remaining after the cycle which will lead to them being cryopreserved. If the transferred embryo doesn’t result in a successful pregnancy, the couple will now have a way to save costs instead of restarting the entire IVF cycle afresh.

The couple wants another child

When the couple, after a successful pregnancy, decides that they would like another child, the cryopreserved embryos can be used to make the process shorter and more cost-effective as they can be preserved indefinitely.

When the couple wants to screen their embryo

Screening of an embryo before the transfer is an important aspect of the process. This can be done either by preimplantation genetic diagnosis or preimplantation genetic screening. They are used to detect any abnormality or disease that may be present in the embryo before the transfer happens. It usually results in the cryopreservation of the embryos, as the process takes a few days. Once the results come back, the doctor then decides which embryos can be transferred through a frozen embryo transfer IVF cycle.

When an elective procedure is chosen

Some researchers have theorized that the fertility medication used in the stimulation of the ovaries does not usually create the best environment in the uterus for implantation. This means that an immediate transfer with a fresh embryo may be less likely to result in a healthy viable pregnancy than using a frozen embryo at a later time. In this procedure, all the embryos are cryopreserved after fertilization. The month after, when the uterus has formed without the influence of the ovary-stimulating medication, a frozen embryo transfer can then take place.

There may be hormonal medication administered in order to enhance endometrial receptivity. This is usually for people who do not ovulate on their own. Alternatively, the doctor may do the frozen embryo transfer as a natural cycle.

An embryo donor is used

Some couples choose to donate their unused embryos to another infertile couple. This makes the process easier for that couple as they do not have to go through the entire process from the beginning.

What are the risks?

There are fewer risks with a frozen embryo transfer than with a full IVF cycle. OHSS which is a risk from the use of ovarian stimulating medication is not a concern in frozen embryo transfer as the ovaries are not stimulated. There is a risk that any time the embryos are frozen then thawed, biopsied, and re-biopsied, they may be lost, or the success rate of the embryo will be lowered when the time for its use comes. This still doesn’t make a fresh transfer the best answer in all cases.

What are the costs of frozen embryo transfer?

It is important to get a clear cost of the procedure from the doctor, as there may be a variety of fees associated with the treatment. This information will help in planning the budget for it accordingly. The average cost for a frozen embryo transfer is between 3k-7k dollars. This includes monitoring, medication, and the transfer proper. The expenses of the initial IVF treatment, as well as the initial cryopreservation of the embryo and storage fees are not included in the price.