Pre-implantation genetic screening (PGS)

Chromosomes are genetic structures found in nearly every cell of our bodies.   

The first cell of an embryo is made up of a set of chromosomes from the sperm and another set from the egg. But if the cell doesn’t have the right number of chromosomes, known as aneuploidy, this can lead to implantation failure or miscarriage.  

Could pre-implantation genetic screening be right for me?

Pre-implantation genetic screening (PGS) is an additional test available to anyone looking to boost their chances of success – you can even ask to have PGS as part of your very first IVF treatment cycle.

That said, if you’ve had treatment before that hasn’t worked, you’ve suffered miscarriages, or if you’re a woman in your mid–30s or older, we might recommend giving PGS a try; it could be that a chromosomal problem is the reason behind your failed treatments. Research suggests that more than 50% of human eggs have chromosomal problems and that this increases with age, so it’s thought to be the main reason older women can struggle to start or grow their families.

During your next cycle, we can use PGS to help us choose embryos with the right chromosomes for transfer, which could give you a better chance of success.

PGS lets us go deeper, allowing us to analyse the genetic makeup of embryos and check that they have the right amount of chromosomes before they’re transferred to the womb.

What does PGS involve?

Usually our embryologists choose the best embryos based on the way they look. This does work, but PGS lets us go deeper, allowing us to analyse the genetic makeup of embryos and check that they have the right amount of chromosomes before they’re transferred to the womb.

By using PGS our embryologists have up to an 85% chance of singling out embryos with abnormalities before transfer. This can improve IVF success rates and reduce both the chance of multiple pregnancies and the likelihood of miscarriage.

In PGS testing, each embryo will have one of four results.

Euploid

This means the embryo is genetically balanced with 46 chromosomes. These embryos can be transferred.

Aneuploid

Aneuploid embryos aren’t genetically balanced and have too few, or too many, chromosomes. We won’t transfer these embryos, as they’re more likely to result in failed treatment or miscarriage.

Mosaic

Mosaic embryos have some cells that are euploid and some that are aneuploid. Depending on the chromosomes affected, we might still be able to transfer these embryos. If you have mosaic embryos we’ll offer you an appointment with a genetics counselor to discuss your options further.

No result

In less than 5% of cases, we simply won’t be able to tell whether the embryo is euploid or aneuploid. These can still be transferred or, in special circumstances, they might be rebiopsied.

If you’d like to know more about pre-implantation genetic screening and IVF, talk to your local clinic or contact us