FET: Everything You Didn't Know You Wanted To Know

What is FET?

When a couple is ready to use their embryo(s), they are thawed and transferred to the female's uterus at the appropriate point in her menstrual cycle. This process is called a frozen embryo transfer (FET). A patient preparing for an FET has blood testing and ultrasound scans that enable the physician to identify the appropriate point in her cycle to transfer the embryo(s).

We are going to be doing a medicated Frozen embryo transfer (FET), otherwise known as a programed FET. This means I will take a course of hormone medication that ensures the lining of my uterus is prepared to receive the thawed embryos.

While an FET is cheaper than IVF, and it is not IVF proper, it is the final puzzle in many IVF cycles. The embryos used in the FET process were harvested from a previous fresh IVF cycle. (Our April cycle)

Healthy embryos from a fresh IVF cycle that are not transferred (in our case, it was a 'freeze all' cycle) can be cryopreserved (frozen) and then stored until they are ready to be used. The process is really amazing, and I am trying my best to also write about it, even though I do not actually understand it all.

In the past, as recently as about 10 years ago is what I understand, the standard practice was to 'slow' freeze the embryos. This process worked, but the success rates weren't that great because there was often ice crystal formation inside the embryo. The newer process of vitrification (Stay tuned, I am going to write about that later) has improved the success rates, as it is more of a 'flash' freezing process. This process has improved the outcomes for frozen embryos. Couples using their snowflake babies can usually expect success rates equal to or better than fresh IVF cycles.  I'm not 100% certain of this theory, but the thought is that an embryo that makes it through the freezing and thawing process is a strong embryo, and a lot of REs automatically do assisted hatching on FETs, which also increases the chances of a positive pregnancy.

What is the Process?

Preservation of Embryos

Before you can have an FET, you have to go through a fresh IVF cycle. In this cycle, the eggs are grown and then harvested. These eggs are then fertilized by one of several techniques. In our case, it was ICSI. Any eggs successfully fertilized become embryos and those are grown for five to six days before the cryopreservation process is performed. These frozen (snowflake) embryos can be stored (at a rate of $50/ month) for at least 10 years or until a couple is ready to use their embryo(s).

Medicated FET

In a medicated (also commonly referred to as a "programmed" FET), the patient takes a course of hormone medication that ensures that the patient's endometrium (lining of the uterus) is prepared to receive the thawed embryo(s).  

Natural FET

"Natural" FETs use blood testing and ultrasound to plan the embryo transfer. Natural FETs require minimal or no medication. 

Transfer and Post-Transfer

When the physician judges that the FET patient's endometrium is ready, the embryo transfer is scheduled. On the day of the transfer, the patient's embryo(s) is thawed and transferred by the physician into the uterus. Embryo transfer is an outpatient procedure that does not require sedation and typically has no side effects. A blood test is done about 10 days later to check for pregnancy. If positive, another test it done one week later to confirm pregnancy. 

At our last appointment I asked my Dr. about the general timeline of an FET cycle. Once we do the baseline ultrasound, (which was originally scheduled for July 14th) he said it is anywhere from 6 to 10 days until the transfer is done. Most of the time though, if during that ultrasound, everything looks good, the transfer is scheduled for one week later. 

Because of the polyps that were found last week, we are having to delay this entire process to allow my endometrium to heal before attempting a pregnancy. LUCKILY, it should only bump our baseline back by about a week as long as everything looks good. 

How Successful is an FET?

Studies from around the world have shown that IVF pregnancies following a frozen embryo transfer are more similar to natural pregnancies than fresh embryo transfer cycles resulting in:

• Increased implantation rates
• Increased ongoing pregnancy rates
• Increased live birth rates
• Decreased miscarriage rates
• Lowered risk of pre-term labor
• Healthier babies

“Since frozen embryo transfers occur a significant amount of time after a woman’s ovaries were stimulated with medications, the hormone levels in the body have had time to return to normal, which mimics a more natural conception process,” says William Schoolcraft, M.D., medical director of CCRM. “This process appears to have a positive impact on the health of the baby.”

It seems that lengthening the time between administering the drugs and achieving a pregnancy lowers the risk of ovarian hyperstimulation syndrome (OHSS), a potentially fatal complication that can be triggered by taking certain fertility medications that stimulate egg production. 

In situations where a Dr. sees warning signs that a woman is at risk for OHSS (high estrogen levels and follicle numbers, rapid weight gain, fluid in the pelvis, etc.), he may recommend freezing all available embryos rather than proceeding with a fresh transfer, as pregnancy. This is exactly why we were not able to do a fresh transfer with our April cycle. Mine was not a severe case, but had I continued with my treatment and put more hormones in my system, or become pregnant, it could have gotten worse. 

What About Future Cycles?

Following a fresh IVF treatment cycle, subsequent FET cycles are less costly for patients. Expenses of both medication and treatment are less than in a fresh cycle. Costs of treatment are reduced since there are fewer monitoring visits, and there is no need for egg retrieval, insemination, or embryo culture.

FET cycles are easier because you do not need surgery (the egg retrieval) or anesthesia. At the start of your FET cycle, estrogen and some other drugs are used to prepare the uterine lining. Daily intramuscular progesterone is added later in the cycle, closer to the transfer.

This means that when we get ready to transfer more babies, we will still have to have blood work done, ultrasounds to check the health of my uterus, etc. which will cost about $6k, and take about two months or so. This seems like a lot of time and money, but compared to doing a fresh IVF cycle, it is a bargain. 

So, What's Our Plan?

As with all plans, they are subject to change and are dependent upon God's plan for our lives. We are approaching our future, especially when it comes to our family, prayerfully and carefully. We are not dead set on any one idea, but are leaning towards the following. 

We do not want to continue this FET cycle process for years and years. We do not desire to have children after I am 40. Considering this, and the fact that we have five embryos, which we do plan to attempt to use, we have considered the following schedule: 

Transfer two embryos in July 2017 (March-April 2018 Due Date)

Transfer two embryos the Fall of 2019 (May-June 2020 Due Date)

Transfer one embryo around December 2021 (September 2022 Due Date) 

This seems like a super crazy baby schedule, but I have peace about it. While, the thought of that many children overwhelms me at the moment, I know I will have the strength and energy to do what I have to do when the time comes. With this schedule, we will not do any transfers until the previous child(ren) are at least 18 months old, and they will be well over two before giving them any younger siblings. 

We have considered transferring one embryo in the middle, instead of two, but we decided against that. We figured while we are in the throws of having twins, have two of everything, etc. we would just keep up the momentum (assuming all the embryos live and result in a live birth.) When we have that last single baby, it will be easy to have only one little one, with lots of help from older siblings. 

We may decide to add some more time in between the transfers if we think we need to, but we will prayerfully make that decision when we get there.