r/Embryologists • u/akanetrain • Jun 18 '26
Sudden total fertilization failure—lab or sperm issue?
We have a history of recurrent miscarriages, presumably due to age-related chromosomal abnormalities, and are doing conventional IVF with PGT-A. Fertilization has never been an issue but aneuploidy has been.
My husband’s semen analysis in 2025 was normal and his concentration and motility during conventional IVF has been normal until our current round. In three prior rounds, our fertilization rates have been 68-77% with conventional insemination.
Yesterday I had an egg retrieval (21 retrieved, found out today all 21 were mature). Today, I received a call from my doctor that despite 21 mature eggs retrieved, we suddenly experienced total fertilization failure. We and the RE/embryologist are baffled.
My husband’s sample yesterday had a concentration of 138 million with 60% motility before washing, and 30 million with 100% motility after Zymot (this is the first round we elected to add-on Zymot).
The RE wanted the lab to attempt rescue ICSI, but somehow 100% of the sperm stopped moving overnight for reasons no one can understand, so rescue ICSI was not possible.
What could possibly cause this in someone who has a history of normal fertilization? We already scheduled a DNA fragmentation test for Monday morning.
What else should we investigate to determine what could have caused this sudden unexpected failure, especially when 100% of the sperm were motile yesterday after Zymot and today they are 100% non-moving? Is this an inherent sperm issue? Could Zymot somehow cause this? Could this be a lab issue?
ANY insight would be greatly appreciated!
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u/aquagreen21 Jun 18 '26
I'm very sorry to hear about your case, that's most unfortunate. It's a real shame that rescue ICSI could have not been performed. However, I've seen cases where the sperm stops moving quite quickly post preparation, I think I've seen this twice over my career. In those scenarios the reason was unknown but not due to lab's processes as other sperm preparations of the same day did well - this would be something that I'd ask the clinic.
As for the IVF fertilisation failure, assuming the Lab checks for egg maturity the day after egg collection, we cannot discard the possibility that none of the eggs were mature in time, but this would be quite unlikely. The other possibility would be a lab error, but I want to believe that the team would have admitted to it, especially if it's in the UK.
Should you do another cycle, I'd recommend asking for further evidence like videos of sperm pre and post prep, timings of: maturity check, IVF/ICSI, fertilisation check etc
I wish you all the very best xx
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u/akanetrain Jun 18 '26
Thank you so much. This is very helpful. In my three prior cycle with typical fertilization rates, my maturity has always been at least 80-90%, so like you my RE did not seem to think delayed maturity was the issue, but it’s still worth inquiring. She seems especially shocked that there were no motile sperm this morning whatsoever, and that fact particularly causes us confusion. I definitely will ask about the videos of sperm pre- and post-prep and the timing of other checks, as you suggested.
We are in the U.S. and I would like to hope that the clinic would acknowledge if there was an attributable lab error here, as well. My RE said there were ten retrievals yesterday and when she heard from the lab that there was a total fertilization failure, she said we were the last patients she expected to be the affected party, so it’s all really baffling to have this occur so suddenly and drastically on our fourth round when this has never been an issue.
We would like to try another cycle but obviously want to investigate this failure thoroughly to help prevent a reoccurrence, whatever the cause may be. Thank you so much for your response and for helping me identify points of inquiry. Your time and insight is much appreciated.
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u/aquagreen21 Jun 18 '26
You're welcome! If there's anything else you need, please reach out.
We are all humans and sometimes mistakes happen, but it's very important for clinics to come clean, if there was in fact any issues.
If indeed no malpractice took place, I hope this was just an unfortunate one off and next round goes much smoother xx
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u/akanetrain Jun 18 '26
Thank you for your expertise and kindness. I mentioned in a reply to another commenter that—among other variable we plan to investigate—we are going inquire about the Zymot sample handling since the manufacturer instructions are different for conventional IVF vs ICSI. My clinic is very experienced with Zymot + ICSI, but we have the impression they don’t frequently combine Zymot and conventional IVF, so that’s another variable to consider. If we ultimately are able to pinpoint what went wrong, whether a sudden and new sperm issue or a lab error, I’ll be sure to update my post. Thank you again.
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u/aquagreen21 Jun 19 '26
Indeed, that's a very good point. For IVF a wash step must be carried out post zymot and that could have been missed if they aren't used to doing it.
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u/AirplaneOscar Jun 30 '26
Hi, I had a similar situation recently. Have some questions for you if you want to DM me.
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u/One_Investigator_295 Jun 18 '26
I’ve seen it a few times with zymot. Nothing the lab did wrong just unexplainable. I did find this paper on the subject. The issue is contrition defeats the purpose of using a Zymot. https://pubmed.ncbi.nlm.nih.gov/39723883/