If you have been researching IVF treatment online, there is a good chance that you may have already come across PGT-A.
Previously known as preimplantation genetic screening or PGS, PGT-A is an IVF treatment add-on that involves taking a cell or a small number of cells from an embryo and checking for abnormalities in the number of chromosomes. By doing this, the doctor can determine which embryos have less chance of developing into a baby or may result in a baby being born with a genetic condition.
Once the cell sample has been removed, the embryos will be frozen and, if suitable, they can be used for a frozen embryo transfer (FET) at a later date. Only embryos without chromosomal abnormalities will be used in treatment. PGT-A is a particularly useful treatment when there has been a failed round of IVF with no clear explanation as to why.
A cycle with PGT-A included will be more expensive than your average IVF treatment package as this may also involve embryo freezing and a FET to pay on top of PGT-A costs. In the UK, PGT-A is not funded under the NHS. At a private fertility clinic, you can expect to pay anywhere between £1,600 and £3,000-plus for PGT-A on a set of four embryos.
PGT-A is traditionally offered to women over the age of 37, as older women are statistically more likely to have eggs with the wrong number of chromosomes. According to the Human Fertilisation and Embryology Authority (HFEA), abnormal chromosomes are thought to be the main reason why older women have difficulties conceiving and are more likely to have a miscarriage or a baby with Down’s Syndrome.
Your doctor may also recommend PGT-A if you have a family history of chromosome problems, if your sperm is at risk of carrying abnormal chromosomes, or if you’ve had several miscarriages or failed IVF attempts without explanation. Although PGT-A is a great way to detect chromosomal abnormalities, it cannot check for specific diagnosis. There is also no guarantee that testing will prevent miscarriage or result in a live birth, as there are many other factors that can impact the final result.
However there are many couples and single women who have benefitted from PGT-A and after years of trying to conceive, the treatment was able to help them finally achieve their dreams of having a baby.
Here we will look at three different case studies who underwent PGT-A and went on to have a successful outcome. This data was provided by embryologists at the EmBIO IVF Center in Greece.
IVF and PGT-A success story – a 38-year-old woman – recurrent miscarriage
- Female patient: Aged 38, BMI 22.
- Male patient: Aged 42.
- Diagnosis: Unexplained infertility/recurrent miscarriage
- Number of previous failed IVF cycles: Two
- Years trying to conceive: Four
This couple had been trying for a baby for four years and two rounds of IVF sadly ended in miscarriage. The female patient had a normal BMI and there was no medical history of any major abnormality.
A number of tests were carried out in an attempt to discover what was causing the recurrent miscarriages. These included a thrombophilia blood test, to check whether the woman’s blood was clotting too easily and karyotyping, a test to examine chromosomes in a sample of cells. Both came back clear. A hysterosalpingogram – an X-ray procedure used to view the inside of the uterus and fallopian tubes and check for any blockages – came back normal. Semen analysis, testing sperm quality and quantity, found no issues and the woman’s ovarian reserve was optimal. As the tests and scans failed to find what was causing the miscarriages and failure to conceive, the couple fell into the unexplained infertility category.
It was decided that the couple should undergo IVF with ICSI, which involves one single sperm being injected directly into the centre of the egg. It was agreed that PGT-A testing should be carried out before the transfer to check whether the embryos were chromosomally normal.
The clinic decided on what is known as an ‘antagonist protocol’, which means it involves the fewest number of injections, and 300 units of follicle-stimulating hormone (FSH) were used.
17 eggs were retrieved from the patient. 14 were mature, 12 were successfully fertilised with ICSI. However only four out of the 12 made it to day six blastocyst stage, when they were biopsied and frozen for a future transfer. Only one out of the four biopsied embryos was found not to have chromosomal abnormalities.
The blastocyst was graded 5AA – meaning it was of optimum quality – and a frozen embryo transfer (FET) took place. This was successful.
The pregnancy progressed and a healthy baby was delivered at 39 weeks, via caesarean section.
Conclusion
In this case, PGT-A genetic screening proved valuable in detecting the only normal, chromosomal abnormality-free, embryo, resulting in a successful transfer.
IVF and PGT-A success story – a 33-year-old woman – shifted implantation window and ERA test
- Female patient: Aged 34, BMI 24.
- Male patient: Aged 35
- Diagnosis: Shifted window of implantation/unexplained
- Number of previous failed IVF cycles: Two
- Years trying to conceive: Four
This couple had been trying for a baby for four years and had two failed rounds of IVF.
The female patient had a normal BMI and there was no medical history of any major abnormality. Just like the couple in our first case study, ovarian reserve was optimal, semen analysis showed no issues and all the tests came back normal. This means the couple were also in the ‘unexplained’ category.
The female patient had already undergone PGT-A testing during her second attempt at IVF. This resulted in three PGT-A normal embryos. She underwent a frozen embryo transfer with a 5AA-graded blastocyst, but the treatment failed.
This time around, the doctor recommended a relatively new procedure called endometrial receptivity analysis (ERA). This involves taking a small sample of a woman’s endometrial lining to determine the best day to transfer an embryo during an IVF cycle, thus tailoring it to the individual patient. The results came back as ‘pre-receptive’, showing that the patient’s window of implantation had shifted.
As a result of this shift, when the patient was preparing for her second FET she was given an extra day of progesterone to ensure that her uterus would be ready to receive the embryo.
A 5AA-quality, PGT-A tested frozen blastocyst was transferred and the treatment was successful. The patient gave birth naturally, to a healthy baby, at 38.5 weeks.
Conclusion
In this case, the ERA test helped the embryologist determine the appropriate window for implantation. Without this test, the embryo would have been transferred 24 hours too early and would have failed to implant.
IVF and PGT-A success story – a 40-year-old woman
- Female patient: Aged 40, BMI 25.
- Male patient: Aged 40
- Diagnosis: Advanced maternal age/slightly low ovarian reserve/thrombophilia
- Number of previous failed IVF cycles: One
- Years trying to conceive: Two
In this case, the female patient had a slightly low ovarian reserve, borderline BMI, but no significant medical history. The couple had been trying to conceive for two years, which included one round of mini IVF. Five eggs were retrieved, four fertilised and two made it to day three blastocyst when they were transferred. The treatment sadly failed.
The couple went through the usual tests and the thrombophilia blood test revealed that the woman had antiphospholipid syndrome, a disorder of the immune system that causes an increased risk of blood clots. She was giving anticoagulant (blood thinning) injections and a low dose of aspirin to help with implantation and the formation of the placenta.
Rather than mini IVF, this time the patient went through more conventional IVF, using an antagonist protocol and 300 units of follicle-stimulating hormone (FSH).
On retrieval day, 11 eggs were taken from the patient, 10 matured, nine fertilised with ICSI and five embryos made it to day five blastocyst. Genetic testing was carried out and two of these embryos were PGT-A normal. One embryo was graded 4AA and the other 4BB.
The higher quality of the two was used in a frozen embryo transfer. The treatment was a success.
However a few weeks into the pregnancy, she started to bleed. The patient was diagnosed with a subchorionic hematoma – bleeding under one of the membranes that surrounds the embryo inside the uterus. She was monitored for a few weeks before the hematoma dissolved.
The patient went on to have a healthy baby at 39 weeks, delivered by caesarean section.
Conclusion
In this case, by upping the dose of FSH, the patient was able to produce more follicles, leading to a much higher number of embryos. PGT-A was then used to identify the embryos without abnormal chromosomes to be used in treatment. The patient’s newly-discovered blood clotting issue was treated with blood thinners and aspirin, which made implantation, placenta development and a normal pregnancy possible.
