Genetic diagnosis/screening such as PGT-A can be performed improve chances of success by ensuring only the best embryos are used. The doctor will assess on every individual case. However, the last decision will be yours.
PGT-A (previously known as preimplantation genetic screening or PGS) involves checking embryos for abnormalities in assessing the chromosomes.
Embryos with missing or extra chromosomes (known as aneuploid embryos) have less chance of developing into a baby or, less commonly, may result in a baby being born with a genetic condition.
Embryos with the correct chromosome number are known as euploid. PGT-A is therefore offered to some patients as a treatment to help identify euploid embryos and avoid transferring aneuploid embryos.
To perform PGT-A, embryologists remove a cell from the embryo, which are then tested to assess the number of chromosomes they contain. The biopsy result is used to reflect the embryo. The embryo can still develop with fewer cells if the removal of cells is done carefully.
Sometimes, the result of genetic diagnosis/screening is reported as mosaic, which means the embryo contains both euploids and aneuploid cells. The proportion of euploid and aneuploid cells can impact the chance of successful outcome if the embryo is transferred.
Mosaic embryos may have a lower chance of pregnancy but there are reports of healthy live births after a transfer of a mosaic embryo.
There are concerns that mosaic embryos may be discarded if PGT-A analysis looks at only the portion of cells from the embryo that all happen to be aneuploid, when they also contain normal cells and may be able to result in a live birth. The doctor can discuss the best options for you after the results.
