Pre-implantation Genetic Screening (PGS) introduced at Waterstone Clinic

Waterstone Clinic is continuing to lead the way in bringing ground-breaking technologies and fertility treatments to Irish families, with the announcement of the birth of the first baby after pre-implantation genetic screening (PGS) in Ireland.

PGS is a complex form of IVF treatment which is recommended for couples who have experienced recurrent miscarriages or repeated unsuccessful IVF cycles. Screening embryos for genetic defects before transferring them significantly increases the chance of a successful pregnancy and decreases the chance of miscarriage. It also considerably reduces the chance of having a baby with genetic problems.

A significant proportion of human embryos which develop normally in the IVF lab have genetic defects and are unable to produce a normal successful pregnancy. The most common abnormality is aneuploidy where one too many chromosomes or one too few are present in all of the embryo’s cells.

Most embryos with chromosome abnormalities will not implant or will result in miscarriage during the first trimester of pregnancy. PGS can improve the potential for a successful pregnancy by ensuring that chromosomally normal embryos are transferred.

With PGS, embryos are generated using a form of IVF treatment known as intracytoplasmic sperm injection (ICSI). They are then screened to find out if they have the correct number of chromosomes. Embryos with a normal number of chromosomes are then transferred into the woman’s uterus.

PGS can be recommended in the following situations:

• Recurrent miscarriages in the past
• Repeated unsuccessful cycles of IVF where embryos have been transferred
• Advanced female age (it is well-recognised that the risk of aneuploidy increases with increasing maternal age)
• Family history of chromosome problems

What is involved for the couple?

If a couple embark on PGS treatment the following is the usual sequence of events in their care:

Step 1. The couple undergo IVF treatment with ICSI employed to fertilise each of the oocytes collected

Step 2. The embryos are kept in culture until Day 5/6 (Blastocyst stage)

Step 3. The embryologist biopsies the embryo (in the process removing a number of cells from the embryo) and these cells are sent to the genetics laboratory for testing

Step 4. The biopsied embryos are cryopreserved until the results of the chromosomal analysis is available

Step 5. One or two of the embryos that appear chromosomally normal are transferred to the uterus

A successful PGS programme is only possible if the laboratory team involved can carry out all of the component processes flawlessly, i.e. blastocyst culture, embryo biopsy and embryo vitrification.

What are the risks with PGS?

• The embryos may not develop appropriately to the stage where they are suitable for biopsy
• There is a risk that all biopsied embryos will be aneuploid and result in no suitable embryos for transfer
• There is a risk that some embryos may not survive the biopsy process
• There are risks associated with IVF treatment itself such as ovarian hyperstimulation syndrome or pelvic infection