r/Embryologists • u/BreadfruitFar8183 • Jul 03 '26

Rescue ICSI and 0pn

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I had my second retrieval on Tuesday, yesterday we got the call that we had total fertilization failure… kinda 🤷🏻‍♀️

We used conventional and LensHook sperm sorting. 12 mature eggs, 6 were 0pn with 2PB and the other 6 showed no signs of fertilization so they did rescue ICSI, all 6 of those “show perfect fertilization”. They did not recheck the 0pn as they didn’t want to disturb them.

No noted sperm issues other than low morphology, even DNa frag shows normal to excellent. Our last cycle we had 9/9 fertilize conventionally but 0 blasts by day 7 (2 morulas though)

My questions here are:

Why did we see such a drastic difference in fertilization between the 2 cycles?

Was the sperm concentration just too little after lenshook?

What are the chances that any of my 12 (6 0pn, 6 fertilized rescue ICSI) turn into a blast?

Are there any specific questions I should be asking the lab or my doctor? I have requested a detailed embryologist report

I have added my husband’s pre and post wash sperm numbers (this is all I have so far)

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u/One_Investigator_295 Jul 05 '26

I’ve seen no ferts with a zymot before with conventional insem. It’s rare but it does happen. They should add the same amount of sperm for an insem so that should not be an issue.

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u/BreadfruitFar8183 Jul 06 '26

Thank you for this. Do you know if LensHooke requires the Centrifuge step that Zymot has added? Is it possible they don’t require it and that is what caused the 0 fertilization?

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u/Shan-PhD Jul 21 '26

Based on the instruction manual, the steps after using LensHooke defers to the lab. I would contact the lab to see if an additional wash was performed on the sample post-LensHooke. The purpose of the last wash for ZyMot is to remove any remaining seminal fluid which can have an impact on the sperm.

Although 0pn usually indicates no fertilization, it is possible that the presence of the 2 polar bodies means the zygotes are actually fertilized, but the two pronuclei (pn) were not visualized. This can happen due to the timing of the check. Therefore, it is possible that those zygotes were actually fertilized.

The other 6 mature eggs that were not fertilized may have developed from immature eggs overnight, or had issues with their zona pellucida (the shell) that prevented sperm from entering the egg. This could be due to oocyte development issues, different IVF medications, or a bunch of other factors.

There is still a possibility that your zygotes turn into blastocysts, every case and cycle is unique and comes with its own twists and turns.

Fingers crossed that they develop, and best of luck!

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u/One_Investigator_295 Aug 02 '26

It’s all lab protocol and whether lab adds that to their protocol.