Pre-implantation Genetic Testing (PGT-A)

Waterstone Clinic was the first Irish clinic to have a successful embryo biopsy service.

Pre-implantation Genetic Testing-A (PGT-A, formerly known as “pre-implantation genetic screening”) is a highly specialised technology that involves the biopsy of embryos to assess whether or not they carry the correct number of chromosomes. Only embryos with the correct number of chromosomes (euploid embryos) will be selected for transfer into the patient’s uterus.

PGT-A is a laboratory technique following IVF/ICSI treatment that significantly increases the chance of having a successful pregnancy after embryo transfer. PGT-A avoids the transfer of aneuploid embryos (embryos that have additional or are missing chromosomes) and decreases both the risk of miscarriage and the chance of having a baby with a chromosomal anomaly.

Who is PGT-A Testing for?

  • Individuals who have experienced recurrent and unexplained miscarriages
  • Individuals who have had repeated unsuccessful IVF cycles (recurrent implantation failure) – where good quality embryos have been transferred into the womb yet pregnancy has not resulted.
  • Female patients of advanced age (it is well-recognised that the risk of aneuploidy increases with increasing maternal age)

What does PGT-A involve?

The PGT-M process involves creating embryos through IVF/ICSI treatment. The embryos are then biopsied, and the genes of the embryos are tested for the named condition. In simple terms, it is IVF/ICSI treatment with an extra testing step: 

  • Following egg collection, the eggs are fertilized with prepared sperm to create embryos.
  • These embryos are cultured and monitored for development.
  • After five days, embryos which appear to be developing normally are prepared and biopsied for the genetic analysis.
  • The embryos are cryopreserved and stored at Waterstone Clinic.
  • The biopsied cells are sent to a specialised genetic testing centre in the UK for testing. 
  • The embryo(s) are diagnosed as euploid (having the normal complement of chromosomes) or aneuploid (having additional or missing chromosomes). 
  • Euploud embryo(s) can be prepared for transfer into the womb, or remain in Waterstone Clinic for future use in a frozen embryo transfer cycle.

Listen to One of Our Many PGT-A Success Stories:


Limitations of PGT-A

Theoretically, the transfer of a genetically normal embryo should increase the chance of a successful pregnancy and decrease the chance of miscarriage. However, PGT-A is not recommended for every patient undergoing IVF treatment: the addition of PGT-A has not been shown to improve overall livebirth rates in the general IVF population. There is a risk of a false negative result (an embryo is deemed normal and transferred but is in fact chromosomally abnormal) and similarly a risk of a false positive result (where an embryo is deemed abnormal and discarded but is in fact chromosomally normal). 


Our PGT team will be happy to discuss your situation with you.

Speak to our team