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The evening after your egg retrieval, things feel different from how they felt previously. Imagine this. For the past few weeks, you have been giving yourself injections, going in for ultrasounds and getting poked for blood tests every few days. Early this morning, it all culminated in you going under anesthesia and having a minor surgical procedure to harvest the eggs. Now the waiting begins. The toughest part physically is now over.
Cora was fortunate to get a great yield of 19 eggs. Not all IVF cycles are as good. As planned, we did ICSI on all the mature ones.
The typical progression for an IVF cycle is that we begin with a number of potential follicles seen on ultrasound. Some are "blanks" or "duds" and don’t have eggs, so the actual number retrieved might be less than that number. After retrieval, some eggs will be immature or abnormal, so only the good ones will undergo ICSI. Then, out of those, only some of them will have fertilized normally.
For example, Cora had about 25 follicles seen on ultrasound. She got 19 eggs. Of those, 17 were mature, and underwent ICSI. Of those that underwent ICSI, 14 became normal embryos. Of the 14 normally-fertilized embryos, 9 looked great on day 3. Up to this point, we were passively watching and waiting for information. Now, it was time to make some decisions.
Our first decision was whether to transfer the embryos today, on day 3, or to wait until day 5 to transfer them when they are at the blastocyst stage. What are the advantages and disadvantages of each option? Although this is controversial among RE’s, I agree with those who believe that a day 3 transfer is better in terms of survivability and a day 5 transfer is better in terms of information to aid selection. In the past, this used to be more agreed upon, but nowadays, with improved culture methods, there might not be all that much a drop in survivability when waiting to day 5.
Look at it this way. On day 3 (3 days after retrieval), Cora has 14 embryos. Nine of these are excellent looking. You might recall, that we judge the appearance of embryos based on cell number and degree of fragmentation. We presume that of these nine, some are genetically perfect and will become babies when implanted. Some won’t. I might make a guess that 30% of them will become babies. If I’m correct, the next problem becomes guessing which of these 9 are the good ones and which are the bad ones. They all look about the same. What can we do?
One option is to wait two more days. In two days, it’s likely that these nine won’t look so similar any more. Some will become great looking blastocysts and some will be so-so blastocysts and others won’t even make it to the blast stage at all. Information from those additional two days now makes it easier to choose which to transfer.
Because of the abundance of great-looking embryos, I suggested waiting the two days. After discussing all the pros and cons, they reluctantly agreed. (I’ll go over the cons shortly and you’ll understand their reluctance).
After another 2 days of waiting, we opened the incubator on day #5 and saw 6 blastocysts. The other three had stopped developing. Now, instead of choosing from all nine, we got the chance to choose from just the six best. This time, I estimated that they had a 45% chance per embryo. Our first decision had been a good ones. Had we come back today only to discover that all 9 embryos failed to develop, then we could have potentially regretted our choice to wait until day 5. Even that is controversial, because there are some who argue that if the embryos don’t make it to day 5, then even had you put them into the uterus on day 3, they wouldn’t have resulted in a baby nor even survived it to day 5 inside the uterus. There are others who argue that the uterus is a better environment than the laboratory and that there is a small chance that some embryos that don’t grow to blast in the lab environment, could have become a baby had they been transferred on day 3. The great fear of this was what really tempted Anthony and Cora to go for a D3 transfer. As it was, they trusted my judgment and now it paid off (this time, at least). 
Our next decision was on how many to transfer. I first made it clear that my estimate of 45% chance pregnancy per embryo was just that an educated guess. So any interpretation of calculations must take that into account. i then told them that their choice now was to transfer 1, 2 or 3 with the following estimated outcomes.
TRANSFER ONE: Fail = 55%. Single baby = 45%.
TRANSFER TWO: Fail = 30%. Single baby = 50%. Twins = 20%
TRANSFER THREE: Fail = 17%. Single baby = 41%. Twins = 33%. Triplets = 9%
Just for comparison, I gave them my calculated estimates for transferring four, even though we wouldn’t remotely consider it.
TRANSFER FOUR: Fail = 9%. Single baby = 30%. Twins = 37%. Triplets = 20%. Quads = 4%
In a future post, I’ll discuss these types of calculations and the limitations in using them. But for the most part, having these numbers in ones head when making decisions is better than total wild guessing, as long as we take them with a grain of salt as not being absolutely guaranteed to be accurate.
I was pleased, when they decided to have me just transfer two.
I did a very smooth transvaginal-ultrasound-guided transfer and we waited for the pregnancy results, remembering that with blasts, the wait is only 10 days instead of 12.
