Pre-implantation Genetic Screening (PGS) - is it for me?
What is Pre-implantation Genetic Screening (PGS)?
PGS is a technique used during in vitro fertilisation (IVF) treatment to check the chromosomes (genetic material) of the embryos for abnormalities. This procedure is recommended in some cases to prevent embryos which have an abnormal set of chromosomes and unlikely to form a pregnancy (or may form an abnormal pregnancy) being transferred back into the womb following IVF.
Who will benefit from PGS?
PGS is potentially suitable for everyone, however it is commonly advised if:
-You are over 35
-You have had several failed IVF attempts (recurrent implantation failure)
-You have suffered recurrent miscarriages (≥ 2 miscarriages)
-There is a family history of chromosome problems or if you have had a previous abnormal pregnancy.
-Your partner is known to have sperm with a high rate of chromosomal abnormalities.
Ultimately as everyone's circumstances are different your fertility doctor will discuss with you whether PGS is appropriate to your own situation.
What does PGS involve?
The PGS procedure requires the embryologists to remove (biopsy) cell(s) from an embryo when they are either 3 or 5 days old. The cell(s) which are removed from the embryo are stored in a uniquely labelled container and sent to our genetics lab to have their chromosomes screened (checked) to ensure they have the correct number. We perform this procedure for all the embryos which are of a suitable quality to be screened in an IVF cycle.
Genetic screening - Array Comparative Genomic Hybridisation (arrayCGH)
The genetics lab use a procedure known as array comparative genomic hybridisation (arrayCGH) to identify the abnormalities in any of the 23 chromosomes in the cell(s) of the embryos. This procedure takes between 24-30 hours to complete, meaning we usually receive the results by the following afternoon.
The genetics lab will report back to us with the results of the screening, providing a detailed summary for each embryo. It is quite likely that the majority of the embryos will be screened as having an abnormal set of chromosomes - this is fairly common and explains why not every embryo is capable of forming a pregnancy or why a significant proportion of pregnancies end in miscarriage. However, in some cases it may that none of the embryos have normal genetic result, in this case we will have to cancel the embryo transfer.
Risks with PGS
IVF treatments carry their own risks. however there are some risks which are specific to the PGS treatment:
-Embryos are very fragile and may therefore be damaged during the process of cell removal
-There is also the possibility that the genetics results may indicate that all the embryos are abnormal and therefore none can be transferred back into the womb.
-Screening of the embryos has an accuracy of 95% and therefore even through PGS has been performed there is still a risk of miscarriage occurring.
If there are any questions you have from reading this blog please contact CARE Fertility.