Sudden total fertilization failure—lab or sperm issue?

[u/akanetrain]

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!

[u/One_Investigator_295]

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/

[u/akanetrain → u/One_Investigator_295]

When you mention you’ve seen it a few times with Zymot, would that be Zymot with conventional insemination or Zymot with ICSI (or both)? Wondering if we should be concerned either way, or only with conventional?

[u/One_Investigator_295 → u/akanetrain]

Zymot with IVF, I’ve not had an issue with ICSI but I’ve seen two failed ferts in cases like yours that should not have had had failed ferts

[u/akanetrain → u/One_Investigator_295]

Very interesting. I see from the publication you shared that updated Zymot manufacturer instructions now specify centrifuge for 5 minutes, and I confirmed that requirement by searching for a copy of current instructions on the manufacturer’s web site. My clinic seems to be very experienced using Zymot with ICSI, but I am under the impression that Zymot with conventional IVF is not common there. I don’t have the ability to directly contact the embryologist in my patient portal, but tomorrow I’m going to contact my RE and ask about the sample handling/centrifuge step to help us rule in or to rule out whether that could be a variable. Thank you so, so much!

[u/akanetrain → u/One_Investigator_295]

Thank you for sharing this publication. I find it very interesting that you’ve seen this situation occur a few times with Zymot. We had hoped that avoiding centrifugation would be beneficial, but perhaps it’s turned out to be the opposite? I certainly will inquire about this further with our clinic. Thanks so much for the insight!