Welcome back to the 5th and final part of my “Behind the Laboratory Door” series, where I have discussed what goes on in an embryology lab during a typical IVF cycle. If you want to catch up you can take a look at part 1, part 2, part 3, or part 4. In today’s post I will discuss what happens on embryo transfer day.
What do your embryos look like by the time we get to the day 3 stage of development? Well, in an ideal world they would have between 6-8 cells and they would have divided nice and evenly without too many fragments. The fragments are small parts of the cytoplasm (cellular material) that can break off each time the cell divides – it is a little like breaking a bread roll and getting crumbs.
There will very probably be a differing spread of qualities, but we will assign a cell number and a grade to each one of them. As mentioned before we are culturing them in individual drops, so we know what each one of them looked like at each of the occasions we took a look at them. What that allows us to do is not only see which ones look best today, but also which ones have been moving along the best from the start.
Two beautiful day 5 embryos in the blastocyst stage of development.
So, do you transfer today or should you wait for day 5 when the embryos should be at the blastocyst stage? As I said, that decision isn’t made until day 3, but if you match the criteria then you will be advised to wait. Those criteria can change a little as well depending on the couple, so that will be gone into in more detail with you at the time of the discussion.
If you have opted for your transfer to be on day 3, we will then have to get the embryos ready for the transfer, so you will either be asked to wait for a short time or even come back later the same day. We need to know how many that you would like to put back and then we will need to carry out the assisted hatching if that is indicated.
The hatching is carried out using a laser, which allows us to apply a very precisely target heat source to make a breach in the zona, which is the outer level of the embryo. The reasoning behind this is that it may potentially help when the embryo gets to the stage of being ready to emerge from the zona.
The yellow arrow shows the hole created in the zona during an assisted hatching procedure.
Once the embryos have been prepared they are then placed in a drop of media in a labeled (and RFID tagged) dish ready for the transfer itself. At this point we will take of photo of the selected embryos and print it out for you – first in what is hopefully going to be your new family album. When you go into the procedure room for the transfer you will have to check that your name is on the IVF Witness screen, and we will verify all that information with you again when we bring round the embryos.
The doctor doing to procedure will have to find out the best way to get through into your uterus, with the help of an abdominal ultrasound and a trial transfer catheter. While that is happening the embryos will be waiting in the incubator and we will be sitting in the laboratory – a good time for us to catch up on the news headlines on the internet, as sometimes this part can take a while as we need to make sure we know exactly where they are going.
Once the doctor is ready there is a tap on the hatch and we bring the embryos through into the procedure room. Once there we will load them up into another catheter, that is passed through into your uterus and the embryos are expelled in a very small amount of media. We also check to make sure that once we have done, that the catheter is totally empty and that the embryos have really gone home to momma!
The procedure is exactly the same on Day 5, apart from the fact that the embryos are not hatched prior to transfer.
Once we have done the transfer any remaining embryos are frozen for future use if the quality is appropriate, and we will continue the culturing until day 6 of development to allow for any stragglers to catch up! After that the laboratory child care services are over and it is up to you!
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