1 day after In Vitro Fertilization
What is observed the day after fertilisation?
17-20 hours after insemination, the oocytes are observed under an inverted microscope at 400x magnification to detect whether or not fertilisation has occurred. A fertilised oocyte is one that has two pronuclei, corresponding to the male and female genetic codes.
We can find correctly fertilised oocytes, unfertilised oocytes and abnormally fertilised oocytes.
Can fertilisation abnormalities be detected?
Abnormal fertilisation can be detected at this time, for example, if two sperm have entered and there is a triple genetic code.
It is important to detect abnormal fertilisations as these oocytes could divide correctly and give rise to morphologically normal but genetically abnormal embryos that should not be transferred under any circumstances.
Are all the oocytes inseminated in vitro fertilised?
No. Under normal conditions, with sperm from the ejaculate, the fertilisation rate in IVF and IVF-ICSI is around 70%.
The first IVF cycle of a couple is diagnostic, and allows us to observe the fertility of each couple. We may encounter low fertilisation rates (5-20%) or even total fertilisation failure.
Are chromosomal abnormalities in the embryo more frequent in IVF than in natural reproduction?
No. Although the average age of patients who undergo IVF to have their first child is higher than the general population, and therefore the risk of embryo abnormalities is higher, in practice no higher rates of genetic abnormalities are observed in children born after IVF.
Neither does the IVF-ICSI process itself carry a higher risk of genetic abnormalities, except for those that would be attributable to the sperm provided by the male partner.
2 days after In Vitro Fertilization
What is observed two days after IVF?
48 hours after IVF, the first embryos are observed. Just like people, no two embryos are the same: each embryo has its own characteristics and at this time it may already be divided into 2, 3, 4 or 5 cells. Nor are all embryos of the same quality within the same cycle.
We can consider that a good embryo is the one that presents, on the second day, 4 cells of equal size, with fragmentation percentages of no more than 10-15%.
However, there are embryos that, suddenly, on the second or third day, have one of their cells disappear, going, for example, from having four to three and then continue dividing, as if nothing had happened. Until now, this fact was considered anomalous, but a study by Institut Marquès has shown that embryos that have reabsorbed cells and then continue dividing until blastocyst (the early stage of embryonic development, which appears between the 5th and 6th day after fertilisation) have the same rate of implantation, evolutionary pregnancy and healthy child born.
3 days after In Vitro Fertilization
What are the embryos like three days after fertilisation?
The embryos must have doubled the number of cells they had on the second day.
A good embryo on the third day is one that has between 7-9 cells, with variable fragmentation percentages of no more than 5-15%.
Blastocyst
What does long culture consist of?
It consists of culturing the embryos until the fifth day after the puncture.
A blastocyst is a mass of cells with a central cavity filled with fluid called a blastocele and surrounded by two different cell layers. The outer one (trophoectoderm) is the one that will give rise to the placenta and the inner one is the one that will give rise to the embryo.
What are the advantages of long culture?
Transferring embryos at the blastocyst stage allows better embryo selection, increasing the implantation rate.
In many cases it allows the transfer of a single embryo, avoiding the risk of multiple pregnancies and it is the ideal technique for patients who have undergone several treatments and have not achieved pregnancy.
Can all embryos reach blastocyst stage?
No. Not all embryos have the capacity to reach this stage, but if the laboratory conditions are optimal and the appropriate culture media are used, 60% of the embryos will reach blastocyst stage.
Blastocyst culture is indicated as long as the embryos at day+2 and day+3 show good morphology.
Can blastocysts be frozen?
Yes. For the process to be successful it is important to vitrify good quality blastocysts, as not all blastocysts have the capacity to implant.
Our laboratory has extensive experience in vitrification and devitrification of blastocysts, with a recorded survival rate of 99%.
Our laboratory is structured to obtain the highest rates of blastocyst stage embryos. For this purpose we have:
- State-of-the-art incubators that allow embryo culture with partial pressure of oxygen.
- Time-lapse technology (Embryoscope) that avoids having to remove the embryos from the incubator to evaluate their embryonic development and therefore avoids the oxidative stress that this produces.
- Special culture media.
- Strict quality controls.
Thanks to these media, 60% of the embryos in culture in our laboratory reach the blastocyst stage.
