Fertilisation of the eggs via ICSI
For the fertilisation we use ICSI: the injection of one sperm cell into each egg. This is because this fertilisation technique provides the most embryos and avoids problems in the execution of the genetic test on the embryonic cells: of all eggs collected and fertilised ninety percent develop into an embryo.
The embryo biopsy
A biopsy consists of the removal of small amounts of material from the embryos that have developed in vitro. This provides us with two options
On day three after fertilisation we remove one (or two) cell(s) for genetic analysis. While the diagnosis is being made on the removed cell(s) the development of the embryos from which the biopsy was taken continues in the incubator, until day five.
The introduction of new techniques has recently made it possible to perform the genetic diagnosis only on day five after fertilisation. With this method we remove a small piece of trophectoderm from the developing embryos, which gives us more cells hence more DNA material.
Because it takes more than twelve hours for us to analyse that material (and it is better not to return embryos later than day 5 or 6), we freeze the biopsied embryos.
Post-retrieval analysis: possible status of each embryo
healthy’ for the genetic defect tested for and of good morphological quality;
- ‘healthy’ for the genetic defect tested for and of poor morphological quality;
- embryo displays the tested defect and is morphologically of good or poor quality;
- In the case of HLA typing: HLA-compatible embryos versus ‘healthy’ but not HLA-compatible;
- no diagnosis reached.