One in 5 Monash IVF patients choose genetic testing of embryos during IVF to select the best embryo and increase their chance of a successful pregnancy. We call our embryo testing program EmbryoScreen.
What is genetic testing in IVF?
Genetic screening of embryos in IVF is known as pre-implantation genetic testing (PGT). Embryos are tested before being implanted to detect issues with chromosomes or genes.
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Normal human cells (embryonic cells) contain 46 chromosomes in 23 pairs – 23 chromosomes from each parent. If the egg or sperm has an extra or missing chromosome, the embryo created will have the same error. This can lead to genetic issues including Down syndrome.
Why do we test embryos?
Embryos may look ‘normal’ under the lab microscope, but even those that grow to blastocyst stage (day 5-6) might not have the right number of chromosomes. Genetic testing of embryos during IVF can help:
- couples suffering recurrent miscarriage
- women over 35
- couples with a family history of chromosomal disorders
- if you’ve had unsuccessful IVF cycles.
Aneuploidy testing lets us handpick embryos with the correct number of chromosomes. Only embryos with the potential to result in a healthy baby are transferred, so the number of treatment cycles needed for a successful ongoing pregnancy can be significantly reduced.
Types of testing
Embryo or blastomere biopsy
This is the most common embryo testing method. We carefully remove some blastomeres (embryonic cells) on day 5 of embryo development to test.
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While we do the genetic testing, the embryos are frozen and kept in storage. When the best embryos are identified, they’re used in a frozen IVF cycle. The remaining viable embryos stay frozen for future use.
How are the cells analysed?
EmbryoScreen is based on cutting-edge Next Generation Sequencing (NGS) technology. It’s one of the fastest and most accurate technologies available.
After the biopsy where the embryonic cells are removed, the sample is transferred to a small test tube. We use a technique called Whole Genome Amplification to make millions of copies of the embryonic DNA.
This DNA is then fragmented (broken up) and hundreds of thousands of these small embryonic DNA fragments are sequenced (analysed) at the same time. We use specialised software to compare each fragment against the human genome (the standard map of human genes).
We can identify extra chromosomes (trisomy) or a missing chromosome (monosomy).