Pre-implantation Genetic Testing Pre-implantation Genetic Testing - Aneuploidy (PGT-A)
In addition to testing for genetic mutations (PGD), embryo freezing has allowed for preimplantation genetic testing for aneuploidy (PGT-A). This used to be called preimplantation genetic screening (PGS), but with the continued evolution of genetic testing recognition of the different subtypes was required. PGT-A looks for abnormalities in chromosome number, such as trisomy 21, which causes Down syndrome, and many others that are likely to result in implantation failure or miscarriage.
Our Pre-implantation Genetic Testing success rates
We are delighted in partnership with Genesis Genetics to be the first to offer this service to patients in Scotland. Patients are already seeing the benefit with a reduced time to pregnancy and a reduction in the risk of miscarriage.Get in touch
What is PGT-A?
In conjunction with our genetics partner, Genesis Genetics we have developed this video to explain what PGS is and can do for you.
The PGT-A Timeline
Preimplantation genetic testing for aneuploidy (PGT-A) is performed as part of your intracytoplasmic sperm injection (ICSI) procedure. This treatment has been revolutionary in preventing genetically abnormal embryos from being transferred. We use Next Generation Sequencing to detect chromosomal abnormalities. This testing method enables to test embryos quickly, and accurately and has now been shown in trials to reduce the time to pregnancy and reduce the risk of miscarriage to <5%.
Step one: Stimulation of the ovaries
In the stimulation phase of an IVF cycle, you will use injectable medications for approximately 8 to 14 days to stimulate the ovaries to produce eggs. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH), both produced naturally within the body, comprise the medications. During this phase, you will come into the clinic approximately 5 to 6 times for morning monitoring, which allows the team to track the progress of your cycle and adjust medication dosages as needed. The trigger injection is the final step in the stimulation phase of treatment. We will use a buserelin trigger, to avoid you developing ovarian hyperstimulation syndrome (OHSS). This injection helps the developing eggs complete the maturation process and sets ovulation in motion. Timing is very important here, as the doctor must perform the egg retrieval prior to the expected time of ovulation.
Step two: Egg retrieval
A doctor will perform your egg retrieval procedure at Glasgow Royal Fertility Clinic. On the morning of your egg retrieval, a doctor will meet with you before the procedure to review your protocol. You will also meet with an anaesthetist, who will review your medical history and will administer the intravenous fluid you will receive prior to the start of the procedure to sedate you.
Obtaining the sperm: If you are using a fresh sperm sample, a member of the embryology team will come to accept the sample. If you are using a frozen sperm sample or donor sperm collected previously, the embryologist will verify those details with you. Our andrology laboratory will wash and prepare the sperm, so that the healthiest sperm are brought together with the eggs for fertilization (after the doctor performs the egg retrieval).
Obtaining the eggs: The egg retrieval itself takes about 20 to 30 minutes. During the procedure, the doctor will guide a needle into each ovary to remove the egg-containing fluid in each follicle. The doctor utilises an ultrasound during the procedure to see where to guide the needle. Recovery will take about 30 minutes and you will be able to walk out on your own. It's important that a responsible adult drive you home after the procedure, as it is unsafe to drive after receiving anaesthesia. The person who is driving you will not need to stay at our clinic during your procedure—he or she should anticipate coming back to the clinic after approximately 3 hours.
Step three: Fertilisation
After the egg retrieval, the embryologist will sort and prepare the eggs and sperm. For ICSI the embryologist will inject one single sperm into each mature egg under a microscope. ICSI is therefore possible with very few sperm and has been revolutionary in how we treat male factor infertility cases or where we have concerns about egg quality.
Step four: Genetic Testing
Once fertilisation occurs and embryos develop over the next 5 to 6 days to the blastocyst stage, an embryologist will biopsy a group of cells from each embryo. The biopsied cells are analyzed in a genetic testing laboratory to determine if they are affected with the genetic disorder that you are known to carry. The blastocysts undergo cryopreservation until the results of the analysis are available.
Step five: Transfer of chromosomally normal embryos
Once we have the results and we know which embryos are affected, an embryologist can then thaw the embryos that are normal and not affected by a chromosomal abnormality. Your doctor will transfer one or more embryos to your uterus in a frozen embryo transfer (FET) cycle.
For some patients all embryos will be shown to be abnormal and no embryos will be transferred. This avoids you having to wait to find out whether the treatment would be succesful after a transfer and prevents you having a miscarriage due to an abnormal embryo.
The actual embryo transfer is a simple procedure that only takes about 5 minutes to complete. There is no anaesthesia or recovery time needed. When your nurse arranges your transfer, she will notify you and provide instructions on when to arrive and how to prepare. You need to have a full bladder for the procedure as a full bladder ensures good visualization of the lining of the uterus and proper placement of the embryos. It's important to drink the specific amount of liquid recommended 30 to 40 minutes ahead of time. You will review your cycle with the doctor and the number of embryos recommended for transfer. Upon entering your procedure room, the embryologist will again confirm your last name and the number of embryos for transfer. The embryologist will load the transfer catheter in the embryology lab with the embryo(s) and then the doctor will insert the catheter into the uterus and push the embryo through with a small amount of fluid. An external abdominal ultrasound provides visual guidance via a monitor to the doctor throughout the procedure. Once the doctor transfers the embryo, he or she will slowly remove the catheter. Since the embryo is invisible to the naked eye, the embryologist will then examine the catheter under a microscope in the lab to ensure that the catheter did indeed release the embryo. The nurse will give you instructions for the following 2 weeks until it's time for the pregnancy test.
Step six: The pregnancy test
Two weeks after the embryo transfer, you will perform a pregnancy test. This test is frequently called a "beta" because it measures the beta chain portion of the hCG hormone emitted by the developing embryo. We let you do this test in the privacy of your own home using a urinary pregnancy test and you then let us know the outcome so we can plan the next steps.
Who does the genetic testing?
We have partnered with Genesis Genetics the largest genetics laboratory in the world who specialises in preimplantation genetic diagnosis (PGD) and preimplantation genetic testing (PGT). Genesis Genetics offers the latest technology to ensure they can accurately identify which and to what extent your embryos chromosomes are affected.
In partnership with Genesis Genetics we are delighted to be able to offer the most accurate and cost-effective technique for PGS. Our full price list can be found here for download, but below is a summary of what the PGT-A package includes. At any time, if you have any questions about the fees, please contact us as soon as possible on 0141 956 0509 to speak to a member of staff.