Pre-implantation genetic testing for aneuploidy (PGT-A), previously known as PGS testing, is a genetic screening test performed on embryos produced during an IVF treatment cycle. PGT-A gives information about your embryo's genetic health to help us select the best embryo for transfer and improve your chance of achieving a successful pregnancy.
This includes CAREmaps, biopsy and set up fee - £1,185
Additional fee per embryo tested - £305
Usually our embryologists choose the best embryos based on the way they look and develop. This certainly does work, but PGT-A lets us go deeper, allowing us to analyse the genetic makeup of embryos and check that they have the right number of chromosomes before they’re transferred to the womb.
By using PGT-A our embryologists can single out embryos with abnormalities before transfer. This improves IVF success rates for some patients and reduces both the chance of multiple pregnancies and the likelihood of miscarriage.
This means the embryo is genetically balanced with 46 chromosomes. These embryos can be transferred.
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 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 counsellor to discuss your options further.
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 re-biopsied.
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 PGT-A; 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 PGT-A to help us choose embryos with the right number of chromosomes for transfer, which could give you a better chance of success.
Patients in their first cycle who have suffered miscarriage previously or who are older than 35 may also wish to consider PGT-A.
Are there any risks associated with PGT-A?
There is a possible but unquantified risk that removing cells from an embryo may damage it and prevent it from developing. However, the first births following embryo biopsy for genetic screening were reported in 1990 and since then, thousands of children have been born, and health risks following embryo biopsy have not been identified as different from IVF/ICSI pregnancies in general.
The necessary freezing and thawing of embryos is highly successful with over 95% survival rate after thawing. There is however, a small risk that the embryo will not survive the process.
What is the evidence for PGT-A?
The independent regulator of fertility treatment, the Human Fertilisation and Embryology Authority (HFEA), has developed a ‘red-amber-green’ rating system and provides information on their website about treatments that are offered on top of your routine fertility treatment – known as treatment add-ons. They consider that the only way to be confident that a treatment is effective enough to be used routinely is to carry out a randomised controlled trial (RCT). In an RCT, patients are assigned randomly to two groups: a treatment group, given the new treatment and a control group, given a well-tried treatment or a placebo.
The HFEA has given PGT-A a red rating because it considers that there is no evidence from such trials that PGT-A increases the overall chances of having a baby. There is information on the HFEA website about PGT-A that you may find useful to consider.
CARE did participate in a large scale RCT called the STAR trial, which was published in December 2019. This trial concluded that there was a significant increase in pregnancy rate in a subset of women aged 35–40 where they had more than two embryos available for testing, although overall in all age groups there was no increase in ongoing pregnancy. However, we recognise that that more robust clinical and laboratory trials are needed to prove whether or not PGT-A significantly increases live birth rates.
It is important to understand that PGT-A will not increase your overall chances of having a baby, although it may shorten your time to pregnancy by helping us select the best embryo sooner. For more information, please speak to your clinic team who will give you detailed patient information documents which outline all the relevant points about PGT-A, or you can visit the HFEA website. We also have some FAQs which you might find helpful read our FAQs.