In an IVF cycle patients often anxiously await news first of how many eggs were retrieved, and then the results after fertilization. In our IVF cycle 16 eggs were retrieved, but only 11 were fertilized. Although that is a great number, I say “only” because that is how I felt at the time. I think everyone wants as many opportunities for healthy, well-growing embryos as possible since so much can happen between day 1 and the day of transfer. What exactly happens is quite confusing!
Clinics use a number of different grading systems and when you get the report from one clinic a 1 can be an almost perfect embryo whereas 1 is an arrested embryo at other clinics. Some people talk of having X number of blastocysts and others will talk about the number of cells and the amount of fragmentation. Some use a letter system, some don’t. There is no doubt about it that when you get your picture of your embryos that will be transferred they are beautiful no matter what, but if you are anything like me you can’t really tell much about the quality of what you are looking at. It is advisable to talk to your doctor, nurse, or embryologist about their particular grading system and what they are looking for in terms of viable embryos for transfer.
My clinic did not really discuss specifics of the embryos, but rather said they would examine them along the way and let us know whether we would be doing a three-day or five-day transfer. When we got the call that they planned to do a five-day transfer because we had “several” good looking embryos we didn’t get many more specifics and no grading report. We were happy, though, with the announcement that we would do a five day transfer because our clinic was clear that a five day was the goal if the embryos were doing what they should.
Always having been an over-achieving student, I was a little disappointed when on transfer day they did tell us the grades of the two blastocysts that they planned to transfer – one A, one B. Throughout the IVF process I joined a message board group of others going through IVF at the same time and at transfer time the talk revolved around those little embryos and how they were doing. I was clueless when it came to discussions of the number of cells and amount of fragmentation because all the information I got was that my clinic was pleased with the two embryos we had to transfer and they thought both A and B embryos had an excellent chance of implantation. Turns out, they were right and both took and there really was no need for me to know (and subsequently worry) about how “perfect” they were.
Many clinics, however, do give specific information and so I thought I would share a simplistic breakdown of the timeline of embryos in IVF to hopefully help those of you who get this kind of information interpret what is going on. Like I said, the number and alphabet system is different everywhere but there are some specific things that all clinics look for. On Day 1 after retrieval the eggs are checked for fertilization. By Day 2 the embryos must have two cells or they are considered to be non-viable. It is preferable that some of them are at the 3 or 4 cell stage of development. On Day 3 clinics like to see at least 6 cells, with some at 8. Babies have developed from Day 3 four cell embryos, but chances are significantly increased when more cells are present. Embryos with higher cell numbers and little fragmentation have a better chance of implanting and if the embryos are not developing as quickly as the clinic would like or are showing increased fragmentation they will often opt to do a three day transfer in hopes that they will do better inside the mother rather than in the lab.
On day four (and often before this) embryos can be seen with 16-32 cells and they are called morulas. Embryos at the morula stage are transferred on Day 3 or Day 5. On Day 5 embryos can be at the blastocyst stage – presenting with 70-100 cells. Embryos that have developed along the ideal progression and exhibit little fragmentation often develop to blastocysts. So, when people refer to the transfer of a morula, a blastocyst or an 8-cell embryo, etc. they are talking about the stage of development that the embryo was in before being transferred. The grading means very little in the grand scheme of things – I just wanted to know that they felt confident that we had a chance at conceiving with the embryos they were transferring and ultimately that is all that matters whether it is 3 transferred on Day 3 or 1 on Day 5 – all we really want is a baby, not just cells of any kind.
Related posts:
