Genetic Screening

Introduction

Genetic screening in fertility care covers several kinds of testing. Some tests look at the parents before pregnancy, while others examine embryos created through IVF before one is transferred. The aim is to give you information that supports careful, informed decisions.

This page focuses on embryo testing, known as preimplantation genetic testing (PGT), and explains the differences between PGT-A, PGT-M and PGT-SR. It is general information and does not replace specialist genetic counselling.

What Is Genetic Screening?

Embryo genetic testing is done during an IVF cycle. When embryos reach the blastocyst stage, usually on day five or six, an embryologist carefully removes a few cells from the outer layer that will later form the placenta. These cells are sent for analysis while the embryos are frozen. When the results are ready, your doctor discusses them with you, and a selected embryo may be transferred in a later cycle.

Because the embryos are created in the laboratory, PGT is only possible with IVF, and it is commonly combined with ICSI. Carrier screening, which tests the parents’ blood or saliva, is a separate option that can be done before pregnancy.

Types of Embryo Genetic Testing

PGT-A: screening for chromosome numbers

PGT-A (preimplantation genetic testing for aneuploidy) checks whether an embryo has the usual number of chromosomes. Embryos with extra or missing chromosomes are a common cause of failed implantation and miscarriage, and they are the cause of conditions such as Down syndrome. PGT-A may be discussed after repeated miscarriage, after repeated unsuccessful IVF cycles, or at older reproductive ages. Evidence about whether PGT-A improves the chance of a live birth is mixed and may differ between groups of patients, so it is not routine for everyone.

PGT-M: testing for a known single-gene condition

PGT-M (monogenic) is used when one or both parents carry a change in a single gene that is known to cause an inherited condition, such as thalassaemia, sickle cell disease or cystic fibrosis. It needs careful preparation, often including testing of family members, before the cycle begins. PGT-M looks only for the condition that has been identified.

PGT-SR: testing for structural chromosome changes

PGT-SR (structural rearrangements) is for parents who carry a balanced chromosome rearrangement, such as a translocation or inversion. These parents are usually healthy, but their embryos can receive too much or too little genetic material. PGT-SR checks for these unbalanced changes.

In India, using genetic tests to choose the sex of a baby for non-medical reasons is illegal, and we do not offer it.

Who May Consider Genetic Screening?

• Couples with a known inherited condition in the family
• Carriers of a single-gene condition, including couples who are both carriers of the same condition
• Parents who carry a balanced translocation or another chromosomal rearrangement
• People who have had repeated miscarriages or repeated unsuccessful IVF cycles
• People who have had a previous pregnancy or child affected by a genetic or chromosomal condition
• Those who want carrier screening before pregnancy because of family history or the patterns of certain inherited conditions in their community

Genetic testing is a choice, and many people do not need it. Your doctor and a genetic counsellor can help you decide whether it is likely to be useful in your situation.

When Is Genetic Screening Recommended?

It is usually discussed when there is a clear reason, such as a known genetic condition, a chromosomal rearrangement or a pattern of pregnancy loss. Genetic counselling comes first. A specialist reviews your family history and test results, explains which test, if any, is suitable, and describes what it can and cannot show. Testing without this step can lead to confusion about the results.

How Does Genetic Screening Work?

1. Genetic counselling. You discuss your history and decide with your specialist which testing, if any, is suitable.
2. Pre-testing preparation. Parents may need blood tests. For PGT-M, a test is usually set up using family samples, which can take several weeks.
3. IVF or ICSI cycle. Eggs are collected and fertilised as in standard treatment.
4. Embryo culture. Embryos are grown to the blastocyst stage.
5. Embryo biopsy. A few cells are carefully removed from each suitable embryo, and the embryos are frozen.
6. Laboratory analysis. The cells are analysed in a specialised genetics laboratory, which usually takes several days.
7. Results and counselling. Your doctor explains the findings, including any unclear or mosaic results, and what they mean for your choices.
8. Frozen embryo transfer. A suitable embryo is chosen and transferred in a later cycle. Prenatal diagnostic tests are still usually discussed during pregnancy to confirm the result.

Preparation and Consultation

Bring your family health history, any previous genetic test reports and details of earlier pregnancies. Questions worth asking include:

• Which test is appropriate for me, and why
• What can and cannot this test detect
• How accurate is it, and could it give a false or unclear result
• What happens if no embryo is suitable for transfer
• How are mosaic embryos handled
• What are the total costs and the likely timeline
• How will my results and data be kept private

Counselling can also help you prepare emotionally for results, whichever way they turn out. See Infertility Counselling for support.

Benefits and Limitations

Possible benefits

• May reduce the chance of passing on a specific inherited condition (PGT-M and PGT-SR)
• May help identify embryos with a typical number of chromosomes (PGT-A), which can support decisions for some patients
• Can give clearer information after repeated pregnancy loss
• Gives families with a known risk more choices

Limitations

• No test can promise a healthy baby, and most birth defects and many conditions are not tested for
• Results can occasionally be wrong or unclear, because a small sample may not represent the whole embryo
• Testing may show that no embryo is suitable for transfer
• Mosaic results are complex and need expert discussion
• It requires an IVF cycle and adds cost
• For people with a good chance of success without testing, the benefit may be limited, and PGT-A in particular does not suit every patient

Risks and Considerations

• The general risks of IVF, such as OHSS, egg retrieval risks and multiple pregnancy (see IVF)
• Embryo biopsy is a delicate procedure. When it is done by an experienced team the risk to the embryo is considered small, but it cannot be zero
• Unclear or mosaic results can be hard to interpret and may lead to difficult decisions
• Genetic information can raise emotional and ethical questions
• Waiting while embryos are frozen and results are analysed
• The continuing need for prenatal testing to confirm results during pregnancy

Factors That Affect Genetic Screening Outcomes

• The number of embryos that reach the blastocyst stage
• The age of the woman, which influences how many embryos are likely to have a typical number of chromosomes
• The type of test chosen and how well it suits your reason for testing
• The quality of the biopsy and of the genetics laboratory
• The nature of the inherited condition being tested for
• Embryo quality and the health of the uterus

Genetic screening can improve the information available to you, but it does not guarantee a pregnancy or a healthy baby.

Frequently Asked Questions About Genetic Screening

Is genetic screening compulsory?

No. It is offered when it may be helpful, and the decision is always yours after counselling.

What is the difference between PGT-A, PGT-M and PGT-SR?

PGT-A checks the number of chromosomes. PGT-M looks for a specific, known single-gene condition. PGT-SR checks for unbalanced results of a parent’s chromosome rearrangement. Your specialist will explain which one, if any, applies to you.

Can embryo testing guarantee a healthy baby?

No. It looks only for particular conditions, and no test can rule out every genetic or health problem. Prenatal care and testing still matter.

Does the biopsy harm the embryo?

Biopsy is performed by skilled embryologists and is considered to carry a small risk when done well. Your clinic can explain its own experience and procedures.

Can embryo testing be used to choose the sex of my baby?

No. Choosing a baby’s sex for non-medical reasons is illegal in India, and we do not offer it.

Do I still need prenatal testing after PGT?

Usually it is discussed. Embryo testing is not a perfect diagnostic test, so confirmatory prenatal tests such as chorionic villus sampling or amniocentesis may be offered.

How long do the results take?

This varies by test and laboratory, and PGT-M can need extra preparation beforehand. Your doctor will give you a timeline when the plan is made.

Why Choose Santana Fertility Centre?

Decisions about genetic testing should never be rushed. At Santana Fertility Centre in Sindhanur, Karnataka, we put counselling first, explain what each test can and cannot show, and help you decide whether testing is right for you. We are honest about uncertainty, and we never present screening as a guarantee.

• Careful review of your family and pregnancy history
• Plain-language explanation of PGT-A, PGT-M and PGT-SR
• Honest discussion of accuracy, limits and costs
• Support with the emotional side of results through counselling
• Care close to home in Sindhanur

You can also read about Egg Freezing, or contact us if you have questions.

This page offers general information and is not a substitute for medical advice. Please speak with a qualified fertility specialist about your own situation.