Chromosomal diseases are divided into two groups:
- pathologies, the reason of which are structural chromosomes anomalies;
- anomalies of the number of chromosomes (aneuploidies). Process of embryo examination on the fact of common anomalies in the number of chromosomes is called preimplantation genetic screening (PGS).
Preimplantation Genetic Screening (PGS) is a genetic test performed on embryos received as a result of IVF treatment in order to avoid miscarriages and birth defects.
PGS is recommended for couples who:
- Had recurrent pregnancy losses
- Experienced unsuccessful IVF programs
- Are over 35
In some cases, the pregnancy is hard to reach because of the wrong number of chromosomes (aneuploidy) of the embryo – it may lack them or have additional ones (monosomy and trisomy). There are small chances that an aneuploid embryo will implant. Moreover, the higher is woman’s age, the higher chances to transfer the aneuploid embryo if the choice is made based exclusively on embryo’s morphology. PGS genetic test helps to detect such embryos and in such way select healthy embryo for the transfer.
Once embryos reach the appropriate stage of development (blastocyst stage) the biopsy is performed – embryologists extract a few cells from embryos obtained as a result of IVF procedure. These cells are taken from extra-embryonic cells that will form the placenta. Afterward, the material taken is being screened for chromosomal abnormalities by using special technique. All biopsied embryos are vitrified and you can start planning Frozen Embryo Transfer as soon as the result arrives. As a rule, it takes up to 4 weeks to get the result.