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Pre-Implantation Genetic Screening (PGS)

What is PGS?

PGS stands for Preimplantation Genetic Screening. It’s a technique used during in vitro fertilization (IVF) to screen embryos for genetic abnormalities before they are transferred to the uterus. In a normal pregnancy, the fetus receives 23 chromosomes from each parent, making it 46. However, due to the defect in eggs or sperm, the count can sometimes be lesser or higher than the standard chromosome count. The condition is called Aneuploidy.

If a couple chooses IVF (in-vitro fertilization) for pregnancy, they might get PGS—Preimplantation Genetic Screening treatment to rule out the possibility of chromosomal abnormality in their child. The test identifies chromosomal defects, like Down and Edwards Syndrome, and abnormalities related to sex chromosomes, like multiple X or Y chromosomes or missing chromosomes.

PGS process | Australian Concept

PGS Process

PGS is part of the IVF treatment. Here’s what the PGS procedure involves:

pre implementation screening

1. Retrieving Eggs:

Since it’s performed in patients who choose IVF, you must undergo the IVF cycle that starts with ovarian stimulation and egg retrieval. Your healthcare provider will prescribe hormonal shots to mature and release multiple eggs from your ovaries at once. These eggs are retrieved through a minimally invasive procedure and are fertilized in a lab.

2. Embryo Culture:

These fertilized eggs turn into embryos in 3-5 days. A professional embryologist closely monitors this process.

3. Biopsy & Screening:

A biopsy could be performed on the third or fifth day of embryo culture. The more developed the embryo is, the higher the number of cells that can be extracted for testing. On the 5th day of embryo formation, the cells are divided into two types—one that forms the placenta and one that forms the fetus. These removed cells are sent to the laboratory for PGS testing.

4. Embryo Implantation:

A biopsy could be performed on the third or fifth day of embryo culture. The more developed the embryo is, the higher the number of cells that can be extracted for testing. On the 5th day of embryo formation, the cells are divided into two types—one that forms the placenta and one that forms the fetus. These removed cells are sent to the laboratory for PGS testing.

Difference between PGS & PGD

PGS and PGD are two common screening tests used in an IVF cycle. While both terms might sound the same, they are different screening tests. Let’s compare PGS vs PGD. PGD (Preimplantation Genetic Diagnosis) is recommended for patients with certain gene mutations or a family history of genetic disorders that can be passed on to the child.

PGS is for patients who have experienced multiple pregnancy losses or are unable to conceive through IVF. Any chromosomal abnormality in the fetus (presence of fewer or higher number of chromosomes than usual) will either terminate the pregnancy automatically or increase the risk of Down Syndrome in the baby. To rule out such chromosomal defects in the baby, you can undergo PGS.

Another difference is that PGS tests the embryo for a specific disorder, while PGS is a broader concept that checks the entire chromosomal structure. The most suitable test for you depends on your reason for considering pre-implantation screening.

Which Couples Should Consider for PGS?

A couple that has experienced recurrent miscarriages or is facing difficulty conceiving should undergo PGS treatment. Here’s what makes you an ideal candidate for preimplantation genetic screening.

Maternal Age: Mothers above 35 have considerably lower chances of conceiving naturally than a woman in her 20s. As age increases, so does the risk of complications in pregnancy. PGS reduces the chances of pregnancy loss or your child being born with commonly known chromosomal abnormalities, such as Down Syndrome, Edwards Syndrome, and Turner Syndrome.

Failed IVF: There can be many reasons why IVF doesn’t work for some couples, one of which is chromosomal abnormalities in the fetus. If you have had more than one failed IVF, it’s advisable to choose PGS for the next IVF cycle.

Male Factor Infertility: Poor or low sperm count in men can result in male infertility and might require surgical retrieval of the sperm. These parents might also need to undergo Intracytoplasmic Sperm Injection (ICSI) for a successful pregnancy. Simply put, couples struggling with male infertility problems should get PGS for a viable pregnancy.

A Family History of Chromosomal Abnormalities: If chromosomal abnormalities run in your family, you might want to get PGS to ensure your child won’t have a chromosomal abnormality.

PGS Success Factors

Preimplantation genetic screening is widely used in conjunction with IVF to increase your chances of achieving a healthy pregnancy. Here are some PGS success factors that can affect your chances of conception and a viable pregnancy after screening:
  • Maternal age
  • Lack of sufficient sperm or eggs
  • Damage to the embryo when extracting the cells for screening
  • Chromosomal defects in all embryos

Success Rate of PGS Treatment

Data shows that the success rate of pregnancy through IVF was 46% in patients who considered PGS as part of the process, and it resulted in 42% of live births. PGS’s success rate depends on the expertise and qualification of the embryologist conducting the test.

It’s performed by a highly experienced professional who can carefully extract the cells from the blastocyst without damaging the embryo. As mentioned before, damage to the cells that will later form into the placenta and the fetus will make the embryo unsuitable for implantation. So, it’s important that PGS is carefully executed.

Benefits & Risks Associated With PGS

PGS is a test for patients who are at increased risk of pregnancy loss because of chromosomal defects in the child. Before considering the procedure, weighing the pros and cons is important. Let’s examine the benefits of PGS treatment.


  • Reduced risk of miscarriage due to chromosomal abnormalities in the child
  • Helps women with less than normal egg count to achieve a healthy pregnancy
  • Mitigate the risk of pregnancy loss in couples with high maternal age and male-factor infertility.
  • Help with family balancing.
PGS Risks
PGS ensures a safe pregnancy for couples trying to get pregnant through IVF, but it comes with certain risks. You must discuss PGS risks with your healthcare provider.
  • You might lose embryos because of cell damage during extraction
  • Results might not be accurate because of technical errors

The Best PGS Clinics in Pakistan

If you are looking for the best PGS clinics in Pakistan, the Australian Concept Infertility Medical Center is your best option. With over 26+ years of experience, we are a highly reputable fertility clinic. We provide you with an environment where IVF can be performed safely, the embryos can grow normally, and they can be tested for chromosomal abnormalities. Call us to learn about IVF genetic testing, its benefits and risks, and cost.

Cost of PGD Treatment

PGS treatment cost in Pakistan can vary depending on the fertility clinic and embryologist’s experience.

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