If a 1PN egg still results in a good embryo, it can be considered as fertilised and the embryo can be transferred if no other embryos are available.
Eggs can also present themselves as 3PN. In the case of IVF, this may indicate entry of more than one sperm. In the case of ICSI, the explanation lies elsewhere.
However embryos coming from 3PN eggs are never transferred under any circumstances.
In the case of ICSI, it may happen that an egg does not survive the microinjection. The egg may be broken or degenerative and can no longer result in an embryo. This happens to about ten percent of injected eggs.
Only if all available egg cells are 3PN or if none of the eggs have survived the ICSI procedure, do we completely cancel the embryo transfer on day 1. We will inform you of this by phone.
In cases where we have only observed 1PN or 0PN, we wait until day 2 to make a decision, as the eggs may still start to divide, as they should. If this is not the case and the embryo transfer still needs to be cancelled on day 2, we will inform you by phone.
Why do I have a small proportion of fertilised eggs?
The average proportion of eggs that is fertilised after IVF is about 60% of the inseminated cumulus oocyte complexes (COCs). After ICSI, this proportion is about 75% of the injected mature eggs.
During IVF treatment, all COCs are inseminated, but we can only see the maturity of the eggs on day 1. It is therefore possible that there are proportionally more immature eggs that cannot be fertilised. Sometimes there are more 3PN eggs (where more than one sperm entered the egg).
If none of the eggs are fertilised (failed fertilisation), we will use ICSI in the next treatment cycle.
In the case of ICSI, failed fertilisation is often linked to the lack of available mature eggs. Some eggs are also very sensitive to the ICSI procedure and fail to survive the injection. On average, this is the case for about ten percent of injected cells. We are certain that the ICSI fertilisation percentage is linked to the quality and source of the sperm sample (sperm from ejaculate or surgically obtained sperm).