Advanced embryo selection: Preimplantation Genetic Screening (PGS)
Preimplantation Genetic Screening (PGS) is a specialised method of embryo selection we can use for your IVF/ICSI treatment cycle.
Through PGS, we can check that your embryos have the correct number of chromosomes to help increase your chances of a successful pregnancy.
All 46 chromosomes in each of your embryos are examined, ensuring only those embryos with a normal chromosome numbers are selected for transfer.
When PGS is recommended and why?
Preimplantation Genetic Screening would be recommended by your fertility consultant in specific circumstances, such as:
- You have a history of recurrent miscarriage – chromosome abnormalities are a common cause of miscarriage
- You’ve had repeated failed IVF cycles
- You’re an older woman – advanced maternal age increases the risk of a pregnancy affected by chromosome abnormalities
What does Preimplantation Genetic Screening involve?
Only embryos which develop to Blastocyst stage in our laboratory (day five or day six of development) are suitable for Pre-implantation Genetic Screening. A small number of cells are removed from each of your embryos by our skilled embryologists who are highly-trained in embryo biopsy.
These cells are then sent from our clinic via courier to a specialist genetics laboratory for genetic testing.
Your biopsied embryos are frozen in our laboratory using the very latest freezing techniques, whilst we wait for the test results to come through.
Survival rates for frozen embryos is over 95% at KNH Fertility Centre thanks to the vitrification ‘fast-freezing’ technique we use, giving you a very high chance of viable embryos for your treatment cycle.
What are the advantages of PGS?
As an advanced form of embryo selection, PGS not only reduces the risk of miscarriage and abnormal pregnancy but also reduces the risk of IVF failure and the need for multiple cycles.
By identifying only those embryos with the correct number of chromosomes, there is also a higher chance of pregnancy from elective Single Embryo Transfer, where only one embryo is transferred to reduce the risk of twins or triplets.
Are there any disadvantages to PGS?
The main thing to consider is that not all your embryos may develop to Blastocyst stage, so you may have no embryos suitable for PGS.Your PGS results may also show that none of your embryos have the correct chromosome numbers, resulting in no embryos to transfer.Only PGS embryos can be transferred in the same cycle – non-selected embryos will not be used at the same time.
What happens to my embryos after PGS?
If chromosomally correct embryos are identified through PGS, you’ll undergo a Frozen Embryo Transfer (FET) cycle using your frozen embryos.
Fresh embryo transfer is not possible due to the time it takes for test results to come through – approximately two weeks – which is why PGS embryos are frozen.
Only one or two PGS embryos will be transferred in the same cycle to reduce the risk of multiple birth. The rest will remain frozen and preserved by us for you to use in future treatment cycles.