Q from U: Is thawing and refreezing embryos harmful to the embryo?

October 27, 2013Carole 50 Comments »

This question came from a reader the other day:

Hi!  I think this would make a great discussion topic. It certainly interests me. My husband and I have 7 frozen early blasts (3 @ 2AA, 1 @ 2AB, 3 @ 2BB). In a perfect world we’d like to do a complete chromosomal screening on them to find which ones are euploid. My RE says this is possible and the embryologist would thaw, biopsy and re-vitrify them. She states the lab has had a lot if success doing this.My concern is for the damage to the embryos. How good are labs at doing this?  What is the general rate of failure?

The short answer is yes, particularly with the newer method of vitrification is used (as opposed to older slow freezing methods), embryo quality seems to be preserved after at least one round of refreezing. In my own lab in Indy, we found ourselves  in the position of having to refreeze when we thawed more than we needed because we assumed fewer embryos would survive.  This happened quite a bit as we transitioned from using slow freeze to vitrification because slow freeze had taught us to have very low expectations regarding embryo quality after thaw. A good thaw in the old days of slow freeze was if more than half the cells in the embryo were intact. That was pretty sad. With vitrificatiom, we saw embryos that looked the same post-thaw as they did when they were fresh. This was very exciting but we had to adjust the numbers of embryos we thawed to get just enough for transfer. We found that we also had pregnancies from twice frozen-twice thawed embryos at any stage, when we used vitrification.

Anecdotal reports such as this one can also be found in the literature:

Live birth of a normal healthy baby after a frozen embryo transfer with blastocysts that were frozen and thawed twice.Fertil Steril. 2005 Jan;83(1):198-200.

This is a report on the birth of a normal, healthy baby after embryo transfer using blastocysts that have been twice frozen and twice thawed. Eight frozen blastocysts were thawed for a frozen embryo transfer. One blastocyst was transferred to the uterus and four of the thawed blastocysts were refrozen. The patient became pregnant but suffered a miscarriage at 7 weeks. The four remaining blastocysts were re-thawed and all four transferred. The second transfer resulted in a healthy singleton birth at 38 weeks.

Here’s a much larger study that looked at the same question in 49 IVF cases.

The efficacy of the transfer of twice frozen-thawed embryos with the vitrification method. Fertil Steril. 2009 Feb;91(2):383-6. doi: 10.1016/j.fertnstert.2007.11.079. Epub 2008 Mar 4. 

This retrospective study in a private fertility clinic  looked at outcomes from 49 women who had excess embryos refrozen. These women had embryos thawed for a frozen embryo transfer cycle, some of which remained as excess embryos. The embryos remaining after the transfer were refrozen and re-thawed in a future frozen embryo transfer cycle. The pregnancy rates and implantation rates between those embryo that had undergone one freeze-thaw versus two freeze-thaw cycles were compared. Implantation rates and pregnancy rates were similar (no statistical difference) in the two groups. Vitrification was the freezing method used.

These studies only involve refreezing and re-thawing so you might well ask–Does biopsying the embryos before refreezing make the embryos less able to survive -quality intact- through a second round of refreezing?

Here’s a mouse study that looks at that question:

Refreezing of murine intact and biopsied embryos by rapid-freezing procedure. Hum Reprod. 2000 Dec;15(12):2577-81.  

The advantage of mouse studies is that you can collect a lot of data in a short period of time, This study looked at how 860 mouse embryos fared after freezing , thawing with or without biopsy, then refreezing and re-thawing. They looked at the implantation and pregnancy rates of mice who had a transfer with these embryos. The bottom line is that the implantation, pregnancy and live birth rates were not statistically different between those embryos with the fewest interventions and those with the most.

With the advent of genetic screening of biopsied embryos, which based on the last ASRM meeting, is becoming more and more widespread in US clinics, the freezing of blastocysts is becoming routine after biopsy and results are good with thawing of these once-frozen blastocysts. Because other patients who have untested frozen blastocysts in storage will likewise wonder if they might benefit from genetic testing which – in their case–would require  thawing for biopsy, then refreezing to save embryos pending genetic test results. So having twice-frozen twice-thawed embryos for embryo transfer will likely become more common.  I haven’t been able to find any studies with large numbers because we just haven’t collected (or reported) the data yet beyond anecdotal reports of a small number of patients in clinics. And of course, it will take even longer to have any long-term outcome data on the health of these kids born from twice-frozen, twice-thawed, biopsied embryos.

Bottom-line. I have every reason to think that this can work and result in good outcomes in terms of pregnancy and live birth rates– longer term outcomes are unknown based on no long-term data. However, as with every intervention in the IVF lab, it can be done poorly or well. Keep in mind, for this to work, freezing, thawing and biopsy must be done with a high level of skill multiple times on the embryo. Highly skilled ART techs can do this. Poorly trained techs in labs that rush to meet consumer demand for either vitrification or biopsy or genetic testing without adequate training won’t be able to pull this off. So as usual, the questions to ask your program are:

How many times have you performed this intervention (biospy and refreezing followed by an FET)?

What data do you have on outcomes from this approach? Implantation rate, pregnancy rate and live birth rate.

The reader who asked this question shared that her RE told them they have a lot of success with this. Great! Then they shouldn’t mind sharing numbers. What’s does a “lot of success” look like in actual data?

If you are the first patient for any new intervention, you have no information to go on and your risk of a poor outcome is not calculable. If there is data, you’ll have a better idea of whether the risk of exposing your embryos to repeated interventions is worth it in terms of possible benefit (information about the genetic status of your embryo). The key is getting enough information as possible about risks, benefits and alternatives before you agree to any medical intervention.



© 2013, Carole. All rights reserved.

50 Responses to this entry

  • Susan Says:

    Thank you! This is some great information. I have 2 follow up questions, if you don’t mind.
    1) Does it matter if they’re day 6 blasts?
    2) Almost all technology gets better with time and I would imagine that there are a lot of couple in this type of position. I know some labs an get PGD results in 24 hours. Do you see the technology progressing enough that the results of the PGD could be done in few enough hours to make a fresh transfer possible?

    Thank you for everything you do!

  • Carole Says:

    Hi Susan,
    In answer to your questions,
    1) Day 6 blasts are in a sense living on borrowed time. The pregnancy rate from day 6 blasts is lower than day 5 blasts. If I had a choice, I would prefer to do the biopsy on day 5 blasts, either fresh or thawed.
    2) Same day results are just starting to become available for some kinds of testing. In the future, it may be widespread. In the meantime, we have 24 hour turn-around which works sometimes and fails dismally other times. We had cases in which flight delays meant samples didn’t get to the testing lab on time which made results were delayed by 24 hours which meant we had to freeze all the embryos late on day 6 (there were biopsied day 5 and we planned to transfer day 6)- when the testing lab finally told us that we couldn’t get results that day. But since there are dismal results from transferring day 7 blasts, we had to freeze all the embryos on day 6 without result and schedule an FET a month later. This was not ideal. So I am skeptical of the fast turnaround results. If it sounds too good to be true, it may well be. Good Luck!

  • Biliana Says:

    Dear Karen,

    I find your blog posts educational and really insightful. Thank you – insight from such an experienced and knowledgeable “fertility lab insider” is invaluable for IVF patients. In IVF, patient has no (or very little) control, and, as we know, knowledge is power, and therefore, I like to arm myself with information, as much as possible (“by failing to prepare, we’re preparing to fail”…).

    I have a question regarding the “fast-turnover” of PGS results. Let;s imagine that, In a perfect world, embryologist can biopsy all blastocysts early on day 5, aCGH identifies a normal one(s) AND the results are back in time for day 6 fresh transfer. Even if possible; is it actually advisable to do a fresh day 6 transfer (as compared to freezing the blasts immediately after biopsy)? What I mean is – if a blastocyst is “ready” to be transferred on day 5, would an additional day in the culture compromise it/its ability to implant? Is there any data/experience with this? From the “cell metabolism” point of view – is it perhaps better to biopsy and freeze the blastocysts, and then transfer the normal ones in a subsequent FET? I know that there’s no uniform answer, and there can be many scenarios, but just for general orientation, what would be the preferred option (if we assume that the results can be delivered in less or close to 24 hours post day-5 biopsy)?

    By the way, what are the typical survival rates for (normal) blastocysts frozen on day 5 and 6, respectively?

    Many thanks in advance,

  • Carole Says:

    Hi Biliana,
    It’s Carole. In answer to yoru questions:Even if possible; is it actually advisable to do a fresh day 6 transfer (as compared to freezing the blasts immediately after biopsy)? What I mean is – if a blastocyst is “ready” to be transferred on day 5, would an additional day in the culture compromise it/its ability to implant? Is there any data/experience with this? From the “cell metabolism” point of view – is it perhaps better to biopsy and freeze the blastocysts, and then transfer the normal ones in a subsequent FET? I just came back from the annual ASRM meeting where embryologists get together and argue about which approach is best. I am not aware of any cell metabolism basis for better results with transfer on day 5 vs day 6. I don’t think that research is out there.

    What we do know is that some labs have reported sightly higher preg rates when they routinely transfer day 5 blasts compared to day 6 blasts. Other labs argue that they get statistically similar results on both days so obviously it can work well under some conditions. Since there is no standardized methods for IVF (we use different media, different incubators, different stim protocols etc etc etc.). You name it, there’s at lease two, if not twenty ways of doing it- most of which work reasonably well.

    What I will say is that from an operational point of view, I like to biopsy all (or almost all) on day 5, freeze all on day 5 (perhaps a few stragglers on day 6) and then get the results from all so that a follow-up FET can be performed. Why do I like this? Because I have all the pertinent genetic data on all my embryos, I am not dependent on airlines running on time to get samples to the genetic testing lab on time. I don’t have to sweat bullets hoping I will get results for my patients before it becomes very late on day 6 to do a transfer. I have been burned by not getting the next day PGS/PGD results on time.

    If you have a good lab that can vitrify the embryos successfully, in my experience, it’s better to call a time-out while you get all the genetic results on all the embryos. Yes, it is emotionally ore difficult to do a freeze all and have to wait a month for transfer, but I believe that the risks overall are less to patients–assuming the lab can vitrify well. Embryos frozen on either day 5 or 6 using vitrification!- should have equivalent survival rates. Hope this answers your question. Good Luck!!

  • Biliana Says:

    Hi Carole,

    First of all, APOLOGIES for the name mistake I made – no excuse for such a mistake!

    Thank You SO much for the prompt response! Yes, this clarifies a lot.

    After 9 IVF cycles (and two recent, consecutive mid-trimester pregnancy losses), I am carefully assessing each and every step for the next cycle. So far, we have always tested (aCGH) day 3 embryos, but now considering to test the blastocysts (aCGH results probably more reliable with higher amount of DNA…also, there’s that fear of potential harm from the day 3 biopsy…then the issues of mosaicism and “chaotic” cleavage stage embryos – though I believe, perhaps incorrectly, that the majority of mosaic embryos would be diagnosed as abnormal on day 3 and on day 5). In any case, because we’d like to try a day 5 biopsy, I am trying to understand the potential “risks” and scenarios…

    Your views and explanations are very helpful. I completely understand your point about the logistics. It is really important to take these risks into consideration when making a decision – by not doing so the overall risk can be much higher (and it’s the final outcome that matters the most…). After everything I’ve been through, I’d be completely devastated if my cycle failed due to “trivial” reasons, such as volcanic ash-like situations…while knowing that it could have been avoided in the first place.

    As for the lab – we don’t live in the US (and US embryology labs are known to be the best), but we are happy with our current lab. However, the freezing/thawing survival rates may not equal that from the US labs. For example, 80-90% and 60% for blastocysts vitrified on day 5 and 6, respectively. Of course, I need to double-check this with the lab, but if the rates are low, then that’s not insignificant…That said, if a normal blastocyst exists, it probably has good chances to survive the thaw…

    Again, thank you most sincerely for sharing your opinion and thoughts – it helps me a lot.

    Best regards,

  • Carole Says:

    No apologies needed about the mistaken name. Good Luck!! Carole

  • Madelyn Ly Says:

    Thank you all for sharing your thoughts and insights. I found this post to be quite detailed and very informative, very much appreciated. Thank you

  • Rachel Says:

    I have similar question regarding thawing and re-freezing of embryos. I have a “day 2” embryo frozen 2 years ago, and would like to thaw it and allow it to culture it to blastcyst stage, then re-freeze. Does this seem possible?

  • Carole Says:

    HI Rachel,
    If the embryos were cryopreserved using vitrification, many labs report that embryos can tolerate at least a couple of freeze/thaw cycles. IF slow freeze (older methods) were used, then some embryonic cell damage is typical with each freeze/thaw so the embryos can’t tolerate multiple freeze/thaw cycles. Good Luck!! Carole

  • Carole Says:

    HI Rachel,
    Yes, if the embryo was vitrified and not slow frozen, it should work very well- assuming the freezing and thawing are done competently and that the embryo is genetically normal and can go on in culture. Lots of labs routinely biopsy and freeze, then thaw, or thaw, culture, then biopsy at blast and even refreeze. Vitrification is well tolerated by embryos. Good Luck! Carole

  • Laura Says:

    Hi Carole,

    Wanted to know your opinion on my situation if it’s not too much trouble. I had 9 5 day blasts frozen in 2010. I had them thawed for pgs screening in August 2016. All survived the thaw. Two of them were discarded due to complex abnormality in one (trisomy 1 & monosomy 18), and partial abnormality (monosomy 18) in the other. I transferred a normal blast that had expanded to a day 6AA (the highest rating my clinic gives) the day after the testing was preformed. Unfortunately it resluted in a miscarriage around 6w. The remaining embryos were re-frozen.This past week I thawed and transferred a 5AB blast that did not implant. The next two that I have that are of the best quality are another 5AB and a 5BB.

    My questions for you are these… Do you think that the 5AB that I had transferred should have started expanding when it was thawed? In other words, do you think that it was a bad sign that it was frozen at a 5AB and put back in with the same rating? The lab thaws about an hour before transfer.

    Next, going forward, do you recommend I transfer the twice frozen 5AB and 5BB, or do you think I should start over with a fresh transfer to improve my odds?

  • Carole Says:

    Hi Laura,
    I would not be too concerned if one hour is not enough for expansion. It can take several hours- so no, it was not necessarily a bad sign. I think that a transfer is less expensive than a fresh cycle so I would transfer any of your existing embryos first. If you do have to do another cycle- hopefully not!- perhaps you can see if they would biopsy the fresh embryos, freeze, send off for results and then only thaw once before transfer. Freeze and refreeze is not ideal, if it can avoided. Having said that, I think I would still give your existing frozen embryos a shot. Good Luck!! Carole

  • Should I defrost my freezer boys? | Combineplaza Says:

    […] a few weeks ago, I came across an article about a relatively new series of procedures. The embryos could be thawed, tested and then refrozen. The tests would show us whether they were […]

  • Maria Says:

    Hello RMA
    Thanks or this interesting article.
    My husband and I have 6 blastocysts (4 day 5 and 2 day 6).(IVF_ICSI). They are frozen since I had OHSS. We transfer the best-ranked embryo, I got pregnant and ended in miscarriage at 6.5 weeks. Since this situation was devastating for us and time is important for us (my husband is 55 and would be his first kid)
    We are considering undergo PGS on the remained embryos but we are not sure about the risk that implies. Our clinic is not straightforward with this information. So, our questions are:
    1.- Is this doable?
    2.- What is the survival rate of an embryo that has been frozen-thawed-biopsied-frozen and thawed again.? Is there any recent literature/research about it?
    3.- Does the PGS alone imply any damage to the embryo? If so, of what kind or to what extent?
    4.- Is there any other relevant information we should consider when deciding go fo PGS?
    Thanks in advance,

  • Carole Says:

    Hi Maria,
    So it is possible to thaw and biopsy embryos and then refreeze but it is not ideal for several reasons: the embryo is in extended culture past day 5, maybe past d6, when you add on a the better part of a day for thaw, biopsy and refreeze; not all labs have done this. If the lab doesn’t have experience with this, it may not go well. Your clinic owes you answers to questions you have– particularly regarding their experience and success rate with thawing, biopsy and refreeze if this is something you might want them to do for you. If they have never done it before or rarely, you need to know that. It is possible to transfer your embryos to another lab with more experience. The repeated freeze thaw is probably more difficult for the embryo than the biopsy procedure, assuming the staff is well-trained and experienced. Trophectoderm biopsy is probably least damaging because these cells are destined to be placental cells, not baby cells.

    It is quite possible that one embryo causing a miscarriage is bad luck and you will have a better experience next time. If you are older – over 35, then the possibility of miscarriage-inducing genetic abnormailites is more likely. I would discuss this with your doctor. Unless they have reason to suspect many of these other embryos are also affected, you might just be better off transferring the ones you have left one at a time, rather than risking their integrity with additional procedures. I think a deeper discussion with your clinic would be helpful. Good luck with whatever you decide. Carole

  • anita Says:

    Hi Carole,

    I am 42 and just underwent IVF cycle #1 with 3 embryo fertilized with grading AA, AB, BB at Day 5 blastocysts. I said YES to PGS testing prior to freezing. Embryologist made an error and forgot to do PGS testing and froze all the embryo. Clinic called me today and admitted to the mistake. They asked if they could re-thaw and do biopsy and freeze them again. I am not sure what i should do now and if re-thawing/biopsy/freezing is good idea. It is unfortunate they made this mistake. What are the chances of losing embryo with thawing and re-freezing technique. Is implantation success rate change with 2 times freezing and 2 times biopsy.

    Please advice.

    Thanks so much for your help in forum.

  • Carole Says:

    HI Anita,
    It is less than ideal to put the embryos through extra freezing and thawing. IF the embryos were vitrified and if the clinic is experienced with doing this, it might be okay. I would ask them to discount some part of the procedure since they created a less than ideal condition for success. The alternative is that you transfer without testing, and do prenatal testing if you do become pregnant. Of course, there is a risk that you will find out you have an abnormal fetus and have to consider termination, exactly what you sought to avoid with PGS testing. I hope they will offer to discount the procedure in this situation. I wish you all the best with whatever you decide. Carole

  • Emily Says:

    Hi Carole-

    Thank you for all of your helpful insight and advice! My question is similar to Anita’s. My husband and I share a common gene related to deafness and decided to do IVF with PGD and all blastocysts were tested before thawing. Two of the blastocysts came back inconclusive, three had the gene and one was perfect (which we already implanted and which resulted in a healthy baby!) The ones which were inconclusive were thawed (once) and biopsied again, and came back normal without the gene and both have a 4BB rating. I feel a little better about them being re-thawed based on what you’ve said above, but I’m concerned about them having been biopsied twice. Is it advisable to move forward with one of those blastocysts or is it a better idea to start over? My doctor thinks we should try those first but even if we get lucky and one of them does result in a pregnancy, I’m worried that the combination of being frozen and thawed twice, and also biopsied twice could affect the baby’s development or cause birth defects or something. Is there a higher possibility of that in this situation in your opinion? Thank you in advance for your help!

  • Carole Says:

    HI Emily,
    I agree with your doctor’s suggestion to transfer the ones you already have. With the newer freeze method (vtrificiation) warming and refreezing is not a big problem for the embryos. In your shoes, I would use what I had already. I expect it will be fine. Good Luck!! Carole

  • Dharshi Says:

    Hi Carole

    I have 9 frozen embryos which were retrieved when I was 36 years old. Just wondering if there are any more studies that have been done on thawing, pgd and refreezing? I am just nervous that this is a relatively new procedure and haven’t been able to find any long term follow up papers. Only considering pgd to avoid disappointment in future transfers but not sure if I should just avoid pgd so I don’t worry about thawing and refreezing.

    Any input would be greatly appreciated!
    Thank you

  • Carole Says:

    Hi Dharshi,
    If your embryos were frozen using vitrification–and the lab was competent- you can expect very good results with thaw- biopsy and refreeze. Embryos tolerate these techniques pretty well if the lab is well trained and experienced. I would ask the lab questions regarding their experience. Would thawing biopsy and refreezing be a very rare technique or is this something they have plentiful experience with? Do they vitrify and warm routinely in the lab with high pregnancy rates for their patients? If you can feel confident that your special needs will be fairly routine and they have good results with previous patients, there is little downside to pgd- if you need it! PGD is not necessarily routine on 36 year old eggs. Over 35 is considered advanced maternal age and your eggs barely qualify so maybe aneuploidy/PGD testing is not so critical–unless there are specific genetic concerns you have because of family history, recurrent pregnancy loss or another reason. I would also discuss this with your doctor. Good Luck!! Carole

  • Nikki Says:

    Hello Carole. Thank you for the informative website! I am 40 yrs old and had embryo cry when I was 37. We have 12 day 5 embryos. Unfortunately PGS testing was not available at the clinic at that time. We have since had one beautiful son when I was 38, and have tried for a second child, with two miscarriages, most recently at 13 weeks form a trisomy. We are now considering transferring one of our frozen embryos, but want to have PGS testing given the two miscarriages and known trisomy. Our initial clinic/lab was less than enthusiastic about the likelihood of damage to the embryos, so we are quite nervous. We did confirm they were frozen by vitrification. What is the likelihood of survival with today’s techniques? There is a center nearby that has performed this procedure around 15-20 times — is that a reasonable number? What questions should we ask the labs?

    Thank you so much!

  • Carole Says:

    Hi Nikki,
    If I understand you, you have a lab that has performed a “warming” followed by biopsy of a previously vitrified embryo- followed by warming and transfer? So they should be able to tell you how many of these cases led to pregnancy/live birth.

    So a couple of things, if it is a blastocyst stage embryo, it will have to be re-vitrified after the biopsy, because there is not enough time usually to get the PGD/PGS results before the embryo is too old in culture. By day 7 in culture, the blastocyst pregnancy rate is very low compared to day 5 and 6 of culture. So that’s one consideration but perhaps not a major one since —-if an embryo is good quality to begin with, and the lab is skilled at vit/warming, then an embryo tends to tolerate repeated vit-warming cycles pretty well. The other question to ask the lab is the percent of the 15-20 cycles of warming-biopsy- vit and then rewarming for transfer that resulted in pregnancy. Did half of the cycles with normal transferred embryos result in pregnancy? That would be really good.

    Unfortunately, even if I could tell you the precise percentage risks for each option, it still wouldn’t be helpful because you might be able to tolerate one bad outcome more than another. At what point, are you better off taking a chance with a transfer (no PGD testing and not further embryo handling) , and running the risk of a bad genetic test- after pregnancy? What is the thing you most want to avoid. Not becoming pregnant again? Becoming pregnant and finding a genetic issue after pregnancy and suffering a miscarriage or having to consider discontinuing a pregnancy. I can’t advise you about which path is the one that you can stomach best. Would you feel better knowing all are tested –even if the additional handling for retesting could cause you to lose some of them? The good news is that you have 12 which is a lot !!- so testing is probably a better option for you than for someone who has 2 embryos in hand. I am sorry that I can’t be much help. I wish you the very best for whatever you decide! Carole

  • Tan Says:

    Hi Carole,

    Just wondering what your thoughts are on my embryo/s please..
    In 2014 I had embryos frozen on day 2. A month later, thawed, grown a day, biopsied with fresh day 3 embryos. I had results on day 5 ready for transfer. 1 fresh and 1 thawed passed testing.
    One fresh boy was transferred (just turned 2 years old). He was a plumped up blastocyst. Chosen to transfer first as he was higher quality. The thawed embryo was successfully refrozen.
    Fast forward to 2017, I have been donating eggs to friends and they’ve been advised to do day 5 testing instead of day 3 (I have a Robertsonian translocation). They were also advised to do PGD test as they collect, not to freeze and test everything later as it’s worse for the embryos. Now I’m worried what this means in retrospect for my frozen embryo from 2014. It should be day 5 blastocyst. Friends previous embryo transfer from my eggs had 95% cells intact but didn’t give them a pregnancy (I know there’s so many different variables with different sperm/uterus now too)..
    Is there anything specifically I should ask about my embryo before thawing it for transfer next year (hopefully once friends are finally pregnant)? In 2014 I thought it would be transferred instead of being refrozen for the sole reason that it had been frozen once already. I was told it had the same chance to freeze/thaw each time. Is this not really true?

  • Carole Says:

    Hi Tan, embryos do tolerate vitrification and warming very well, so that might well be fine. If you want to have the embryo thawed, biopsied and refrozen, on day 5, in order to allow time for PGD results, there is not a lot of time to do this before the embryo has been in culture too long because we haven’t perfected culture past day 6. So you might ask about that– the timing of the extra testing and your transfer. Good Luck!! Carole

  • Holly Says:

    Hi Carole,

    Wondering if you have any insights into my situation. I completed an IVF retrieval in 2014. At the time, I was 33 years old. We transferred 1 day 5 blast that resulted in my now 2 year old son. We had 6 additional day 6 blasts that were biopsied for PGS and frozen. Unfortunately, something went wrong and results for all 6 of my blasts came back as “non conclusive.” The lab cannot figure out what went wrong, but refunded my money since they assumed it must have been a lab error (they say this has never happened to them before). Now, we are trying for our second child and just completed a FET with a 5AA day 6 blast, which resulted in a chemical pregnancy. I am wondering about thawing, rebiopsying and refreezing our remaining embryos, in order to avoid future losses. My clinic says that they have thawed, rebiopsied and refroze embryos several times with good success, but that they have not transferred any of those blasts back so they cannot speak to the effect on pregnancy rates (apparently no one has been in my situation – retesting has usually been done in cases where one embryo out a larger batch came back non conclusive. So, even if that embryo came back with euploid results, the family chose to transfer back embryos that were only frozen/biopsied once so far and are still saving their twice biopsied/frozen embryos). My clinic is known to be very good, with great thawing/pregnancy rates. However, it makes me nervous that they have not done transfers of twice frozen/biopsied embryos. What would your advice to me be? Should I just continue to transfer my blasts without rebiopsying them? Or is it reasonable to rebiopsy them? I am just so worried that there is something wrong with all of them, and that I am going to continue to have chemical pregnancies …

  • Holly Says:

    Also, I forgot to mention that my lab definitely uses vitrification!

  • Helen Says:

    Hi Carole,

    I have a day 5 4BB once frozen embryo vs a day 6 4BB twice frozen embryo. Both were frozen by vitrification and not PGS tested. I did IVF when I was 31 years old. From what I’ve read, day 6 embryos are not as good as day 5s but refrozen embryos are also not as good… Which one of those embryos do you think would give a better chance of pregnancy?

  • Carole Says:

    I would probably go with the day 5 embryo first. Good Luck!! Carole

  • Carole Says:

    Hi Holly,
    Re-biopsying and retesting will not increase the risk that the embryos will be abnormal so that risk remains the same. There is some risk that added technical interventions can reduce the overall robustness of the embryos and their ability to implant. You need to weigh your need to avoid another miscarriage with a possibly increased risk of reducing the viability of the embryos a little bit. I think either strategy could work; you just need to decide which risk you can better tolerate. Good Luck!! Carole

  • Carole Says:

    Hi Tan,
    You don’t mention how old you are. Three years time is a big deal between 30 and 35 or 35 and 40, but if you are in your twenties, three years time probably hasn’t changed your fertility much. I probably would transfer your frozen embryo from before first in any case. And also, if your friends are good friends, they won’t mind if you complete your family first before donating more of your eggs. You might consider being a little selfish here to be sure you have use of all your good eggs to complete your family, before your fertility declines with advancing maternal age– as is the normal situation as women age.Good Luck!! Carole

  • Jennifer Says:

    HI, Carole,

    Thank you for your insight. We have a glitch in our plans with our embryos—our fertility clinic ‘forgot’ to test the embryos on Day 5 prior to freezing. The implantation is supposed to occur in a few days, and the error was just realized. We wish to select the sex of the implanted embryo. They are recommending that they thaw and refreeze 10 embryos to allow them to cherry pick a male. What do you think of this? We are worried about the increased risk to the potential child due to their mistake.

  • Carole Says:

    Hi Jennifer,
    The issue is that beyond day 5 in culture, embryos tend not to implant as well. Ideally, you would thaw and transfer them on day 5. If they can be thawed, immediately biopsied and refrozen in a few hours–making the time in culture as short as possible— and assuming the lab has excellent biopsy and vitrification warming and re-vitrfying skills, then it might be okay. It is not ideal. If you need to select a male because of a medical risk to the child ( genetic issue associated with gender), it make more sense to take the risk. But it is up to you – whether the best chance of becoming pregnant at all with any gender is of more value to you than reduced chance of pregnancy, but with the preferred gender. Good Luck with whatever you decide!! Carole

  • SarahK Says:

    Hi Carole, I did a donor egg FET and 8 embryos were frozen on day 3. They were all 8 cell and one was a 6 cell. My clinic had frozen them as in 3 slots so 3-3-2. We did our first slot of 3, all 8 cell no fragments embryos and it was a disheartening negative on beta hcg today. I have endometriosis but no pain and fibroids but my uterine cavity is smooth without any adhesions as confirmed after a hysteroscopy.
    Can you suggest what should be done to improve implantation..? We didn’t do any PGD as donor was 26 and had two healthy kids. I have two slots of 3 and 2 embryos left. Should they be checked for any abnormality despite the fact that they were unfragmented 8 cell on day 3?
    Please help with any suggestion. I’m very exhausted and desperate for help.
    Thank you.

  • SarahK Says:

    And do 3 days embryo transfer have a lower implantation rate then a 5 day blast? Can these be thawed and wait to turn into blasts before the next transfer. Or is that not an option anymore.

  • Carole Says:

    HI Sarah,
    Yes, thawing and culturing a couple more days before transfer is an option. This tests the embryos to see if they can get to day 5-6 and become blastocysts. It is possible to biopsy the embryos after thaw on day 3 and get results for aneuploidy before transfer. There are also various protocols to prime the uterus. All of this is possible. I would have a conversation with your doctor about what the options are for what might be done differently next time in their clinic, based on their experience. I would not push the lab to try something new that they haven’t done before. That is likely to go badly if you are a test case for a new technique. I would ask questions about what they might do differently. The lack of fragmentation is not correlated to anything. Perfectly pristine 8 cells can have an abnormal number of chromosomes.And a heavily fragmented embryo can be genetically normal. I also would check their pregnancy rates using donor embryos relative to other clinics in your area and against the national average. As a general rule of thumb, don’t use below average clinics. Hopefully your next attempt will be successful! Good Luck!! Carole

  • Anonymous Says:

    Hi Carole. The protocol they gave me was from day 2 of my period they started me with cetrotide injections for 4 days and I was taking estrofem 1+2+1 in a day. And closer to the transfer I was on cyclones pessaries three times a day. My lining was 0.84 when they transferred. It was a FET. Unfortunately I chose the donor myself, was a friend so can’t blame the clinic for it. I’ve paid so much everywhere and now waiting for the second try with the embryos. I’m now finishing my first period after the transfer. Can you pls suggest some protocols for a better uterine lining? Could there be any immunological issues with me that’s why I don’t have implantation.
    Thank you Carole for taking time out to do this for people like myself. god bless you !!!

  • Sarah Says:

    Dear Carole, thank you for the reply.
    I was from day 2 of my period given one cetrotide injections for 4 days.and estrofem tablets 1+2+1 .along with this cyclogest pessaries were given two days before transfer Twice a day and my lining was 0.84. However a day before the FET I had a bit of a brownish spot and the doctor checked and since the lining was still the same and was no time of my period she carried on with the transfer.
    I chose the donor myself and paid a lot to get her on board. Clinic didn’t give me the donor.
    Can you please suggest any tests if needed for me to see if something’s wrong and why won’t the embryos implant like any immunological issues? I’m finishing my first period after the transfer last month. When should I have the next transfer. Please suggest some protocol to prime the uterus. I would be so greatful to you for your help.
    Happy Holidays and God bless you Carole Xx

  • Carole Says:

    Hi Sarah,
    I am so sorry you are having such a difficult time. I wish I could be more help but I am not a medical doctor- I am a lab person so I don’t feel qualified to answer questions about the best endocrine priming for the uterine lining. I know that different doctors have different opinions. Please ask your physician these questions. Your doctor owes you an explanation of why they are proposing certain treatments and what you can expect. Wishing you MUCH GOOD LUCK and a fast path to parenthood!! Carole

  • NG Says:

    Hi Carole,
    I am 36, retrieved 11 eggs in my first IVF cycle of which 9 embryos were frozen today – grade 2, 8 cell embryos. Doc has said PGS is not necessary ( I have had one Miscarriage 2 years ago from a naturally conceived pregnancy).
    I am bit confused as to why did the clinic not let them develop to 5 day blastocysts and what happens next month when they thaw, culture to 5 day stage and then refreeze the (extra) blastocysts again.
    Is this advisable to thaw all or only some of them?
    What are the chances that grade 2 embryos develop into healthy 5 day blastocysts vs grade 1. And also how different are pregnancy rates for grade 2 and grade 1 embryos.
    Is there any statistic for this? What are the questions I should ask them. Thank you so much, your Q&A is so insightful!

  • Carole Says:

    Hi NG,
    It is fine to freeze (vitrify) the embryos at 8 Cell stage and then thaw and let them grow to blastocyst stage. The additional culture confirms that they survived thaw and are proceeding normally. There are a lot of different ways to do this. Some labs prefer to grow them out to blastocyst stage and thaw (warm) them right before transfer- just long enough to observe that they look intact in culture. Refreezing them again at blastocyst stage is also tolerated well- assuming vitrification is used. Vitrification is the modern freezing method that is very well tolerated by embryos with minimal or no loss of cells. I would ask them what their success rates are for transfer of grade 1 vs grade 2 blastocysts. After all, their success rates are of most interest to you since they are handling your embryos. Good Luck!!! Carole

  • Hope Says:

    Hi Carole,

    I am 34 and my husband is 51. I had my egg retrieval last week and we were able to freeze 8, day 5 blasts. Unfortunately, we didn’t do PGS testing before freezing them and are strongly considering it now. I spoke with my lab today and they said it wasn’t ideal but still possible. I’m very worried about losing my viable blasts in the thaw refreeze thaw refreeze process. The lab uses the vitrification method which gives me a little hope. Any insight of yours would be so very appreciated.

    With gratitude and warmth,

  • Carole Says:

    Hi Hope,
    The lab is correct, it is not ideal to manipulate embryos after day 5, but assuming that the techs can perform the biopsy quickly, refreezing can be done the same day with vitrification and generally, embryos tolerate this fairly well. Since you are under 35, you should be in a lower risk group for chromosomal abnormalities so it is not obvious why you want to do PGS now. If your doctor isn’t recommending it, you might be better off trying a transfer with one of your embryos “as is”. The only reason to do PGS is to eliminate the risk of transferring an embryo with a abnormal chromosomal condition, like downs syndrome, or other problems that are not compatible with life. Obviously, there are other options to consider if you didn’t want to continue an abnormal pregnancy. Do you need to be 100% certain the embryo is normal? and possibly slightly reduce your chance of pregnancy? Can you tolerate the uncertainty of whether the embryo was normal until later in the pregnancy when other diagnostic tests would tell you? Anyway, there are no right or wrong answers for these questions, just what is comfortable, feels right, for you and your partner. Good Luck!! Carole

  • NG Says:

    Hi Carole, thanks for your inputs. They will thaw all of them since they expect only 1-2 good quality blasts from the grade 2 embies. They did say it’s not unusual for these to be top quality blasts. They do use vitrification. And probability of success of grade 2 Vs grade 1 is 40 percent to 50 percent.. so I am not complaining. Considering my Age and amh they prefer a FET at blasts stage rather than 3 day stage.
    Just wanted to let you know. Also wanted to let you know that your posts are really helpful. So thanks again!

  • Carole Says:

    Hi Anonymous,
    This previous blog post might be some help.http://fertilitylabinsider.com/2013/10/q-from-u-causes-of-thin-uterine-lining-and-treatments-to-improve-receptivity/
    Good Luck!!

  • Carole Says:

    Hi Anonymous,
    An older post may have some useful information. This is really a question for your reproductive endocrinologist, not a lab person like me. http://fertilitylabinsider.com/2013/10/q-from-u-causes-of-thin-uterine-lining-and-treatments-to-improve-receptivity/
    Wishing you MUCH GOOD LUCK! Carole

  • Jurga Says:

    Hi Carole,
    I wonder if you could advise in my situation. I have 10 day 1 (n/a stage) embryos frozen using slow freezing technique. The embryos will be 1 year old in April 2019. I am 36 years old. There is a possibility to transfer my embryos to another clinic that uses vitrification. I am planning to implant the embryos in 2 years time. My question is if it is worth transferring the embryos to another clinic now to thaw them and refreeze using vitrification? I’d like to know which option would cause less damage to the embryos – leaving as it is or refreezing using vitrification? Also, if I left my embryos with the ‘slow freezing clinic’ would they thaw all 10 embryos or 2 on a day of implantation? My concern is if they thawed all 10 that means unused ones would be frozen using slow freezing again.
    Thank you very much in advance,

  • Shannon Says:

    In the process of Ivf. Pgd testing done immediately following blastocyst stage. Frozen then thawed for fet, however fet could not be done due to high cervix, and the doctor had problems getting a catheter into the uterus. It will be rescheduled hopefully for next month. They now have to re freeze and thaw, again. Will this pose a possible a risk to the embryo, that otherwise wouldn’t have happened had the procedure gone as it should? I am concerned, as this shouldn’t have happened ideally, and this was our million dollar embryo. Thank you.

  • Laila Says:

    Hi everyone,

    I posted here about five months ago, but cant remember if it was this exact thread. was asking about refreezing and PGD. I wanted to post again to give some hope for anyone who might be asking.

    I am 15 weeks pregnant with an embryo that survived international transfer between clinics, thawing, PGD testing and then refreezing and thawing. It can happen so stay positive!

  • Carole Says:

    That’s great news Laila!! Thanks for looping back. Wishing you and your family all the best!! Carole

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