Preimplantation Genetic Screening

Preimplantation Genetic Screening (PGS) is a state of the art laboratory technique in which the embryo is tested for certain chromosome abnormalities prior to being transferred into the uterus.

The aim is to increase the likelihood that a healthy embryo will implant to reduce the possibility of an early miscarriage. PGS would also be expected to reduce the incidence of fetal abnormality and birth defects related to chromosomal disorders.

What is preimplantation genetic screening?

Preimplantation genetic screening – also known as preimplantation genetic diagnosis when used to detect a known genetic abnormality, such as when one parent is at risk of passing on a serious genetic condition – is a technique used in IVF treatment.

Five or six days after fertilisation, a trophectoderm biopsy is carried out on lab-grown embryos. This procedure takes a small number of cells from the embryo. At this stage, the embryo is made up of 100 to 150 cells, and the biopsy will not harm it. These cells are then tested to ensure the embryo from which they came is genetically healthy, and that all chromosomes are present.

Only genetically healthy embryos will then be transferred to the woman’s uterus, dramatically increasing the chance that the pregnancy will not result in a child with a serious genetic condition being born. Screening is normally 98-99 per cent accurate.

Advantages of preimplantation genetic screening

As preimplantation genetic screening checks embryos for known genetic defects prior to implantation, it has a significant advantage over testing which takes place post-conception (such as amniocentesis, or chorionic villus sampling).

Preimplantation genetic screening removes the need to make difficult decisions regarding whether or not a pregnancy should be terminated, as no pregnancy can occur until the embryo has been tested for genetic abnormalities and transferred to the uterus.

Preimplantation genetic screening does not harm the embryo, and can reduce the risk of miscarriages or unsuccessful pregnancies, especially for older mothers. If one partner is at risk of passing on a serious genetic condition, preimplantation genetic screening is a swift, accurate way to minimise that risk.

Is preimplantation genetic screening for me?

Preimplantation genetic screening is helpful in the following cases:

• If you are an older mother – women aged 35 years old and above have a higher risk of producing embryos with genetic abnormalities, which can lead to unsuccessful pregnancies, or children with a serious genetic condition.

• If you have had repeat miscarriages – two or more miscarriages in a row can indicate genetic problems.

• If your partner has low-quality sperm – genetic abnormalities can come from the father, especially if they are of advanced age or suffer from a medical condition.

• If you have had IVF failures in the past.

Success rates of preimplantation genetic screening

Preimplantation genetic screening does not guarantee a successful pregnancy – it checks for known genetic abnormalities rather than all possible defects, and there may be no healthy embryos in the batch, or the pregnancy may not be successful for other reasons. However, it does help. Testing is 98 to 99 per cent accurate, meaning that at-risk embryos have a higher chance of success when preimplantation genetic screening is carried out.

For more information on preimplantation genetic screening, contact us at FertilityOne2One today.