Embryos: The Creation, The Wait, and the Next Big Step by Laura Sirkovsky-Kauffman
The next step in your IVF journey or process after an egg retrieval is the formation of embryos. This is also the next step for those who are using egg donation. The hope is that the sperm and egg (when they meet), will come together and begin to form the cells that will become an embryo! Let’s look at how we can make this happen.
IVF has two different processes for an embryo being created. The original way of embryo creation for IVF was that an egg would be placed into a petri dish and it would then have sperm surrounding it. These are sperm that have been “washed”. This means that the sperm you are using (via your partner or a donor) has gone through a process where they have cleared out the sperm that look strange, don’t swim in the right direction, etc. The hope is that one sperm in the dish will swim its way to the egg, make its way inside, and fertilize. If it does, it will then hopefully begin to form the cells that are required of a healthy embryo. We will come back to this in a moment.
ICSI (intracytoplasmic sperm injection) is the process of taking a tiny needle (called a micropipette) and directly injecting a singular sperm into an egg. This bypasses the stage where the sperm has to naturally penetrate the egg. ICSI is often a recommendation made for couples that are dealing with male factor infertility as it leaves less to chance. Similar to conventional IVF, the hope is that when sperm and egg meet, they will fertilize and begin to form the cells that are required to become an embryo.
The 5 Day Wait
The day after your egg retrieval and or the day after egg and sperm have had a chance to meet, you should get a call from your clinic. This call will inform you how many mature eggs you had (for those who had an egg retrieval and this means they were a good size to try to fertilize). They should then give you the big news of how many embryos are starting to form. Now, to give you perspective, the number you start with, is most often not the number you will end up with.
A usable embryo is an embryo that makes it to what is called the blastocyst stage. An embryo can reach the blastocyst stage on days 5, 6, or 7 following being fertilized. Some clinics will give you a call every day to tell you how many of your embryos are continuing to grow. Some may stall and or just stop, and some will (hopefully) make it to the blastocyst stage. Most clinics will not call you until day 5 to tell you how many have made it. Some clinics will allow embryos to continue to grow until day 7, but not all do. I suggest looking for a clinic that will give you an extra buffer.
For reference, when I received my initial call from my clinic, I was told of the 29 eggs that were collected, 24 were mature, and that 21 were starting to become embryos. On day 5, 4 embryos had made it to the blastocyst stage, and then on day 6, 9 more had officially made it to the blastocyst stage.
Testing the Embryos
Depending on what country you live in, what clinic you go to / your personal feelings on the matter, you now have to decide if you want to pursue genetic testing of the embryos. This is known as PGS or PGTA testing (Preimplantation Genetic Screening and Preimplantation Genetic Testing for Aneuploidies- they are the same thing). From this testing, you can find out if the embryo has any chromosomal abnormalities (such as Down Syndrome) and you can find out the gender of the embryo.
When you look at an embryo under a microscope, you will see that an embryo tends to be circular in its shape. On the outer layer of the embryo is a layer of cells that will eventually become the placenta. They will remove a couple of cells from this layer and that is what will be tested. While you are waiting for the results of your genetic testing, your embryos will be frozen in time until they are ready to be transferred into a uterus.
Test results time wise vary from clinic to clinic however they will tell you as to whether or not your embryo is euploid, aneuploid, mosaic, or chaotic.
A euploid embryo is an embryo that has a normal number of chromosomes and will be selected to transfer back into the uterus. Aneuploid embryos are embryos that have been deemed to have an abnormal number of chromosomes. Mosaic embryos are when the genetic testing is not conclusive and they are uncertain as to the health of the embryo. Lastly, chaotic embryos are when genetic material is missing and therefore the testing can not properly be conducted.
Following my genetic testing of 13 embryos, it was determined that 6 were euploid and therefore healthy for transfer. Some clinics will consider transferring mosaic embryos if that is all a couple has at the end of their journey. This is something to discuss with your doctor.
Getting to this step is a major milestone and preparing for transfer is the next big part of the IVF journey. You and your partner should celebrate as this alone is a huge accomplishment.
Laura Sirkovsky-Kauffman is currently pregnant from a frozen embryo transfer after undergoing IVF. She loves to talk to others about their experiences with getting pregnant and pregnancy. You can find her at @siftrva on Instagram or at www.siftrva.com.