If you've read this blog you know that I had the chance to freeze some of my own eggs. The egg retrieval procedure happened two weeks before my 46th birthday.
At the time - and most likely still - there was no clinic in the United States that I could find who would do the procedure for a woman my age, except one. And when I had my initial phone consultation with the doctor he wanted me to understand clearly that I would be spending around $10,000 and, because of my age, I would be lucky of getting maybe one, or possibly two, viable eggs at the most. I told him I still wanted to have him do the egg retrieval.
But the result, to his amazement, was that I ended up producing six mature eggs, two immature ones, and the germinal vesicle cell. The last, the germinal vesicle cell, was something I had insisted, before going under anesthesia, that he retrieve as well.
All of this had taken place in September of 2009, so now nearly five years ago. I never asked my doctor about the freezing process that would be used. I didn't know then that there was any more than one kind of freezing process being done.
It has only been in the last year or two where I found out the process that is the newest, and best, for a more successful outcome in having the egg be viable when "thawed" is called vitrification.
Prior to this "new" method of vitrification the freezing process for eggs was done under a controlled-rate, slow-cooling method. The method involved slowly cooling down the oocyte until it finally freezes. A major disadvantage of that approach was that it caused ice crystals to form inside the embryo’s cells (blastomeres), damaging them and thus reducing viability because they couldn't survive the freeze-thaw.
Vitrification, on the other hand, is associated with higher survival rates and better development compared to slow-cooling. Vitrification involves freezing the egg about 600 times faster than the slow cooling method. The ultra-rapid process is so fast that it literally allows no time for intracellular ice to form. As a result, vitrification allows for less trauma to the egg, and thus, a higher statical rate that the egg would survive the cryopreservation when being thawed.
So, the bottom line is that the method now used to freeze oocytes - vitrification - is associated with higher survival rates and better development compared to the older method of slow-cooling.
But, like I said, back in 2009, with no clinic in the U.S. willing to take someone as old as me I had to just go with the only one that would. And whatever method of freezing eggs that clinic used in 2009 was what it was... and I didn't even know to ask what that might be.
In the intervening years, especially now, since I know more about how much better a freezing method vitrification is than what had been used before - slow-cooling, I wondered what method my eggs were frozen under. Five years ago is like 50 years in terms of how fast science changes and improves its methods.
Anyway, because my eggs were frozen five years ago I thought that the cryopreservation method used was most likely the slow-cooling one because that's what seemed to be used back then. Lately, I would have thoughts like, I don't even know how viable those eggs were going into the freezing process, much less if the slow-cooling method was used, how would they fair coming out of the freezing process intact.. viable.
Finally, a month or so ago, I came across some form from the clinic and I thought, I'm pretty sure back in 2009 my eggs would have been cryopreserve by the old method, but I should call them and find out for sure. I just felt like if there were any chance that doctor was more on the cutting edge of cryopreserving eggs back then maybe the possibility existed that vitrification was the process he used.
So, a month ago I called the clinic where I had the procedure done. A woman who answered said someone would look into my question regarding what method was used to freeze my eggs, and would call me back, but they never did. I decided to call again and this time I got the doctor's administrator and she took down my number said she would look into it herself and call me back. And a day later, just a few days ago, she did. The process she said, of how my eggs were cryopreserved, was vitrification.
*Deep sigh*
I have no idea how things will turn out with my almost 46 year old eggs, but that the newest method, the method used across the board now - as opposed to then - the method that has a really high success rate of thawing out without damage, is the method that my eggs were frozen under. One more dragon slayed.
Now, my thoughts can be relieved of that question and go on to the next: how long can my eggs actually last as viable being frozen for so many years. As one report notes: there isn't enough data yet to know how long eggs can be cryopreserved - but clinicians haven't noticed any problems with oocytes stored for as long as 48 months. As long as 48 months... what about five years?!!!
I guess that dragon will have to be slayed whenever the time comes...
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