Pre-Implantation Genetic Screening (aCGH)

What is Pre-Implantation Genetic Screening (PGS)?

PGS allows the screening of all of the chromosomes and an enables broad screening as opposed to just one single abnormality in the case of PGD. Newer techniques allow us to examine all of the chromosomes and to see if an embryo lacks, or has additional chromosomes, a condition called aneuploidy.

Genetically normal embryos have a higher chance of implantation and the resulting pregnancies have a lower chance of miscarriage. Testing embryos by aCGH may increase the likelihood of pregnancy and reduce the chances of a pregnancy loss.


Who is it for?

This technique may be helpful specifically for those who:


How does PGS Work?

Initially an IVF cycle using PGS begins in the same way as any other, with the stimulation of the ovaries to produce eggs, followed by their collection and fertilization

When the developing embryos are five days old a few cells are microsurgically removed and taken for testing (alternatively a single cell is sometimes taken when the embryos are just three days old). The embryos under analysis do not leave the IVF clinic. They are either returned to the incubator or cryopreserved (frozen) until the test results are available.

The cells are analysed independently by aCGH and the test results indicate how many copies there are of each chromosome, revealing any abnormal embryos. Results are available within 24-36 hours although this may reduce to within 4 hours in the near future with the introduction of the ultra-rapid PGS protocol. We can then choose appropriate embryos for transfer based on these genetic results and the standard embryological assessment

One, two or three of the embryos without abnormal numbers of chromosomes are transferred to the uterus so that they can develop. Any remaining unaffected embryos can be frozen for later use.

Those embryos that had abnormal chromosomes are allowed to perish or may be used for research (with your consent).


What are the risks of PGS?

No test is 100% accurate, so following any genetic screening we recommend that patients who become pregnant undergo prenatal testing.