Preimplantation Genetic Testing

for Aneuploidy (PGT-A)

Preimplantation genetic testing for aneuploidy (PGT-A), formerly PGS, is a reproductive technology used to determine if an embryo has the correct number of chromosomes prior to transfer to the uterus.

Fairfax Diagnostics PGT Lab

PGT-A Frequently Asked Questions (FAQs)

Looking for more information on PGT-A at Fairfax Diagnostics? Here are some frequently asked questions.

Embryos commonly experience natural gains and losses of chromosomes during the first few days of development. This causes the embryo to become abnormal (aneuploid) in chromosome number, a natural phenomenon that can result in IVF failure and other poor reproductive outcomes. Couples undergoing IVF can use PGT-A to significantly increase the chance of a pregnancy and birth of a healthy child by choosing and transferring only chromosomally normal (euploid) embryos.

The use of PGT-A can accurately identify the occurrence of aneuploidy, allowing selection of only normal (euploid) embryos and may be considered in all IVF cycles. Those who may especially benefit from PGT-A include: couples who have experienced repeated pregnancy loss, partners of advanced maternal age, and couples who have experienced multiple IVF failures despite producing morphologically (structurally) good embryos.

PGT-A: Guide to Preimplantation Genetic Testing of Embryos in IVF

This informative and clear introduction by Claire O’Neill to PGT-A is of value to the general public exploring key aspects of the PGT-A technique.

Clinical Indications

Indications for the use of PGT cover a wide range of reproductive issues falling into three general categories: (1) to determine that an embryo has the correct chromosomal content prior to transfer, avoiding embryos with chromosomal gains, or losses called aneuploidy, (2) to detect inherited single-gene disorders, or (3) to identify structural chromosome rearrangements and/or unbalanced translocations. PGT-A is ideal for cases of repeated pregnancy loss, advanced maternal age, and multiple in vitro fertilization (IVF) failures despite morphologically good embryos.


Women of advanced reproductive age (over 38 years of age).


Couples with a history of recurrent unexplained miscarriages.

Failed IVF

Couples who have experienced several failed IVF cycles.

Sperm Abnormalities

Partners with certain types of sperm abnormalities such as low motility, low sperm count, and/or severe male factor infertility.

Family Balancing

Couples who have children and desire family balancing.

Why is embryo selection important for IVF success?

By using PGT-A with your IVF cycle, only embryos with the correct chromosomal content are transferred increasing the chances of a healthy pregnancy and reducing the risks for miscarriage.


PGT at Fairfax Diagnostics is powered by Next Generation Sequencing technology using Illumina’s MiSeq platform.


After receipt of the embryo biopsy samples, DNA is isolated from cells and amplified using polymerase chain reaction or PCR. Sequencing libraries are then prepared from amplified DNA, pooled (combined), and normalized to equal amounts. The pooled DNA libraries are sequenced on Illumina’s MiSeq platform and data is exported for analysis.

Genome Coverage

Using Next Generation Sequencing, PGT-A at Fairfax Diagnostics is designed for full and balanced coverage of all chromosomal regions with high resolution for determining chromosomal defects. The library prep protocol generates over 1 million individual genomic reads per embryo, spanning all 24 chromosomes with an average resolution of 1 Mb.


Next Generation Sequencing using VeriSeq for DNA library preparation is designed to identify whole chromosome aneuploidy in samples obtained from embryo biopsy. Results are interpreted using BlueFuse Multi data analysis software which empirically determines chromosomal copy number values and is optimized for preimplantation genetic testing.