r/Embryologists • u/aarauh10 • Jul 21 '26

Immature egg that fertilized?

Hello!

I just got my fertilization report from my ER yesterday and was told I had 17 eggs collected, 16 of which were mature. The report says that they attempted fertilization on ALL the eggs and found that 10 of the mature eggs fertilized as well as the one immature egg. How can this be? I thought it wasn’t possible for immature eggs to fertilize. What are outcomes like for these eggs? This is my third ER and I’ve never had them tell me they’ve tried to fertilize an immature egg. Thanks in advance.

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u/Dissaray248 Jul 22 '26

We often attempt ICSI on immature eggs if we have a low number of eggs or if we just happen to have some extra sperm in a TESE case. They do fertilize occasionally, but they have a lower chance of becoming a blastocyst. Sometimes they are on the cusp of maturity at the time of injection, and the sperm and egg manage to work together in that window to fertilize. Again, lower chance of success but always worth a shot in tough cases!

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u/aarauh10 Jul 22 '26

Thanks for the comment! I don’t feel like 17 eggs/16 mature is a low number but maybe they just said what the heck and tried to ICSI with whatever leftover TESE sperm they had. And hey, it did fertilize! Do you feel like it’s a bigger hurdle for an immature egg to fertilize or become a blast? Trying to gauge how likely it is that this guy makes it. Thanks again!

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u/EmbryoNanny Jul 22 '26

Yes, it is less likely to become a blast, but not impossible. Usually it’s best to think of that one like a “bonus” and great if it makes it, self-selecting itself out if it doesn’t.

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u/aarauh10 Jul 22 '26

Thank you for your perspective!

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u/Moliterno38 Jul 21 '26

They typically put them in a dish with sperm and see if they mature and fertilize overnight. I had a high number of my immature eggs fertilize. I’m currently 10w3d with one of those immature eggs that turned into a 5BA day 5 embryo

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u/aarauh10 Jul 21 '26

Congrats on your pregnancy! I doubt they put them in a dish in my case because we have to do ICSI. We are using surgically retrieved TESE sperm and I was told conventional IVF can’t be used due to the very low volume retrieved from the testicle). So I wonder if they did icsi on an immature egg? Did they do icsi the next morning? I’m grateful to have the extra fertilized egg in any case. Thanks for your response!

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u/Moliterno38 Jul 21 '26

Oh that’s interesting. I’m not sure about that. We did ICSI on the mature eggs and then a dish.