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PGT-A (Aneuploidy)

Preimplantation genetic testing (PGT)

Next generation sequencing (NGS) is the most well-established of the available methods for pre-implantation genetic testing (PGT) It allows us to comprehensively screen embryos for abnormalities in all 24 chromosomes before transfer. Genetically normal embryos have a higher chance of implantation and the resulting pregnancies have a lower chance of miscarriage. Testing embryos by NGS may therefore increase the likelihood of pregnancy, reduce the chances of a pregnancy loss, and improve the odds of a live birth outcome. Standard PGT is termed preimplantation genetic testing for aneuploidies (PGT-A). This covers the majority of requirements for patients looking to reduce the chance of miscarriage or infertility often associated with advanced maternal age.

We have chosen to work with Igenomix for the genetic screening of embryos as they have been established by pioneers in the field of genetics and have proven themselves to be extremely efficient and thorough when delivering results to us. They offer a comprehensible genetic counselling service when needed also. Particularly for patients where a hereditary condition has been identified (Please see PGT-M single gene disorder).

The Igenomix team has over 15 years of experience in embryo testing and has published a wide range of scientific papers in this area. As well as being on the cutting edge of technology, Igenomix also has a vast range of practical experience, and work with a number of large UK based clinics. They also have testing laboratories in Spain and Dubai. The Igenomix laboratory in the UK is fully accredited (UKAS) and provides access to the very latest methods for the genetic evaluation of sperm, eggs and embryos.

Step 1: Assisted Reproduction

Initially an IVF cycle using PGT-A begins in the same way as any other, with the stimulation of the ovaries to produce eggs, followed by their collection and fertilisation. The embryos will then remain in culture in the laboratory for 5-6 days. On day 3 of embryo development the embryos will be assisted hatched in preparation for biopsy at the blastocyst stage.

Step 2: Embryo Biopsy

When the developing embryos are five or six days old and have reached the blastocyst stage a few cells are micro-surgically removed from each embryo by our highly trained biopsy practitioners and taken for testing

The cells are placed in special test-tubes and sent by courier to the surrey based Igenomix laboratory. The tested embryos are then immediately cryopreserved (frozen) at the Lister fertility clinic until the test results are available.

Step 3: Genetic testing

The cells are each analysed independently by NGS and the test results indicate how many copies there are of each chromosome, revealing any abnormal embryos. Results are available to us within 2 weeks. Once we have the results they will be shared with the patient and if any of them embryos are suitable they can be returned to the patient during a frozen embryo replacement cycle (FET).

No test is 100% accurate, so following any genetic screening we recommend that patients who become pregnant undergo prenatal screening if deemed appropriate by the obstetric team.

If you have a specific chromosome rearrangement that needs testing (translocation or inversion) please see the PGT-SR information

If you have a specific single gene mutation that needs testing for please see the PGT-M information.

The HFEA "traffic light rating" for PGT-A on Day 5 is "amber", suggesting that there is a growing body of evidence which is showing promising results but where further research is still required.

Read more about the HFEA traffic light system on fertility "add ons". 

A fertility "add-on" is an "optional extras that you may be offered on top of your normal fertility treatment, often at an additional cost. They’re typically emerging techniques that may have shown some promising results in initial studies but haven’t necessarily been proven to improve pregnancy or birth rates."

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The Lister Fertility Clinic
The Lister Hospital
Chelsea Bridge Road
London SW1W 8RH

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