What is Frozen Embryo Transfer (FET)?

This is probably the most important thing for you to read.

Freezing the Embryos are “Cryopreservation” is doing using a technique called “Vitrification” to ensure the Embryos get frozen and recover back to life without incurring any injury. Too much to grasp? Ok, in simple terms now.

Every human Embryo is a collection of living cells. These cells have a lot of water, which is a good thing. But this can be a bad thing if while undergoing freezing it turns into ice. Icy crystals can be like swords that can stab other structures inside the cell. Not so good right? So now, to ensure that the water does not convert into ice, we have a technique called Vitrification. This basically means putting the Embryos in a solutions which has ‘Cryo-protectants’ that will dehydrate the cells so that they will essentially be in a gel-like state. Ok, it’s a little bit more complex in actual life, but the fundament is the same. Vitrification solutions were made earlier by the Embryologists, now they are commercially available. After properly exposing the Embryos in the vitrification medium and ‘loading’ them onto a freezing device, they are then plunged into liquid nitrogen (medical grade) where they will be suspended at -196 degree Celsius temperature safely for as long as we like. Previously it used to be a big deal when people got pregnancies with Embryos frozen for many years, now it's a common occurrence. At Janini IVF, providing the best egg donation Treatment in Delhi NCR, we have Dr. Akanksha Mishra, an infertility specialist doctor in Delhi, who is a post-graduate from Oxford University, UK who personally oversees and performs the Vitrification procedure. Dr Akanksha has more than 15 years of experience freezing Embryos, and trust me, in her hands the freezing - thawing results exceed 98-99% survival. She is one of the most renowned and coveted experts in not just Embryo vitrification but also oocyte or egg vitrification which is a much more complicated procedure. In her hands, your Embryos are safe.

Ok, but why Freeze the Embryos in the first place?

Good question. There are many good reasons for doing this. But let’s start with the simple ones first.

• In a ‘conventional’ IVF cycle, there is an attempt to generate 12-16 mature follicles so that we can have as many good eggs from one cycle. This would then generate more than enough Embryos to be transferred in a single transfer attempt (we do not and we should not transfer more than 3 to 4 Embryos in one go). Quite obviously, if we have, let’s say, an arbitrary number of 10 Embryos, and we are only transferring 3 of them in a fresh cycle, we don’t want to simply throw the remaining extra Embryos down the basket. No way. No how. They’re just too precious.
• The extra Embryos then frozen could be brought back to life whenever we want. After a few weeks. After a few months, or after many years as well. Supposing God forbid the first transfer attempt failed. In spite of putting 3 good Embryos. Does this mean the entire money is down the drain? Does this mean you’d have to go through the agonising process of daily injections, alternate day scans and the anesthesia for egg retrieval? No, no and no. You won’t need to. Because we have the surplus Embryos frozen from the first egg retrieval itself, when we fertilised all those eggs and generated all those Embryos. So now, with a much reduced cost and virtually no effort, you have a complete new transfer attempt(s). Look at it this way - you get to pay only once, but get three or four transfer attempts, depending on the number and quality of Embryos formed. Trust me, with that many transfers, we haven’t seen patients not carrying a baby home.
• There could be things that can go wrong during the process of ovarian stimulation and Embryo culture. For example, you can develop OHSS (Ovarian hyper stimulated syndrome). This is a rare condition in which your ovaries bloat up and you have unpleasant symptoms of pain, constipation, etc because the ovaries are enlarged much more than normal. We cannot transfer Embryos in this situation because if we do, this will worsen the OHSS because of certain hormone interactions (yes, your baby releases hormones in your blood). Again, there are several other conditions that preclude doing Embryo transfer. We cannot transfer, for example, if we find a polyp in your endometrium (inner lining of womb). Fluid in endometrium - nope, can’t transfer. - go for freezing. Opting for PGS? - Go for freezing. So you see, Freezing actually save your precious Embryos so that we can transfer them when things are right.
• We had mentioned the frozen Embryos do not incur any damage and are as good as fresh Embryos for as long as required. This is becoming apparent now. Frequently we are getting requests from couples who had mishaps in life making them lose their grown-up son or daughter. Many times we get couples who conceive with IVF once and after 4-5 years start thinking of having another child. Guess what, the Embryos that you made in 2018 will be still good to go in 2015 when you decide to have another child. So in 2025, you would not need to spend money again on a repeated IVF cycle. No need of injections. No need of egg retrieval operation. The Embryos will be as good as they were and you can conceive using them!
• Beliver it or not, the results of frozen Embryo transfer are better than fresh Embryo transfer. Now here things will get a little interesting. How can anything frozen be better than fresh? Let me explain.

At the best IVF Center in Delhi, when we do IVF or ICSI, remember what was the first step? It was to start giving you injections of ‘Gonadotropins’ that will stimulate your ovaries to grow follicles. These are basically hormonal injections and we cannot do without them if we want to make Embryos. Unfortunately, these very hormones, although being safe, have some side-effects on the uterine lining whom we doctors called “endometrial advancement” or “displacement of implantation window”. Try this analogy - suppose if someone asks you to bake a cake in the oven. Instead of 200 degree for 30 minutes one thinks of using 500 degree for 10 minutes. What will happen? Yes, the cake will burn. Something similar (although not as dramatic) happens with the endometrial lining because of the gonadotropin injections. This may reduce chances of conception and that means wasting the precious Embryos because the uterus was not prepared to accept them. So what to do? - freezing is the answer! We freeze the Embryos, give a period of rest to the endometrium, and transfer the Embryos only when things are right.

Corroboration of this theory is found in modern scientific evidence - a lot of published papers suggest that frozen cycle results are better than fresh cycle results. And this is what we do.

Is there any concern about Embryo Freezing?

As mentioned, Embryo freezing is a safe and effective means of enhancing the success rates. Freezing the Embryos do not make them inferior in any way and in our lab we have more than 99% recovery of frozen Embryos. Our lab also, apart from having the best Embryologists, have stringent measures of quality control and quality assessment to have a perpetual level of excellence maintained during all times. We have the highest International levels of safety, hygiene and scientific measures to ensure there is no human or procedural error at any point of time.

How is the FET (frozen Embryo transfer) done? What are the steps?

FET can be in a:

1. Natural cycle - no hormones are given to you and the Embryo transfer is done after thawing when the uterus is ready for accepting the Embryos or 2. Medicated cycle - in which we give oestrogen hormone to prepare your endometrial lining and when it is mature we give progesterone so that the endometrium becomes receptive.

• Preparing the endometrial lining takes about a couple weeks or so to develop to satisfactory levels.
• Once the endometrium is deemed to be good after checking ultrasound, the Embryos are then ‘thawed’ - brought back to life a few hours prior to the actual transfer procedure
• The transfer dish is prepared and finally a decided number of Embryos are then transferred inside the uterus using a small catheter. This procedure is simple, quick and does not require anesthesia.
• Blood test to check for pregnancy is done after 2 weeks of transfer.
• Medicines - including oestrogen and progesterone are continued so that the Embryo keeps getting nourishment inside the uterus.

What is the success rate of FET?

Success of a frozen cycle depends on many parameters like the age of the partners whose Embryos are made, quality of gametes, person doing the Vitrification procedure and Embryo thawing, endometrial lining and medicines given. In experienced and skilful hands like ours at Janini IVF, the success rates of an FET program would be no way inferior than International standards. Assuming the Embryos are endometrium are optimal, we have consistently seen over 70-80% results in frozen Embryo transfer cycles over the period of many years now. Frozen Embryo transfer also works wonderfully well in those patients who’ve had failed attempts of fresh IVF cycles elsewhere.

For how long can our Embryos be kept in your laboratory?

Right now the Indian Government allows for 10 years. After 10 years we would notify you of further plan of action. The health of the Embryos would not be affected in any way.