PGT-A, PGT-M, and PGT-SR: Three Different Tests With Different Purposes

Key Takeaways

• PGT-A checks chromosome numbers; it does not screen for every genetic condition.
• PGT-M looks for a specific inherited condition identified in a family.
• PGT-SR checks for chromosome imbalances linked to a parental structural rearrangement.
• No PGT result guarantees pregnancy or a healthy baby. Testing needs individual counselling.

PGT-A, PGT-M, and PGT-SR: Three Different Tests With Different Purposes

The types of PGT testing can sound confusing when you are already discussing injections, egg collection and embryo transfer. You may hear that embryos can be “genetically tested” and assume one test checks everything. It does not.

At a fertility consultation, the useful question is: What specific concern are we trying to check? Your age, pregnancy history and family genetic reports may lead to different answers. Sometimes, testing may not be advised.

What Are the Three Types of PGT Testing?

PGT means preimplantation genetic testing. It involves testing a small sample of cells from an embryo created through IVF, before deciding which embryo to transfer.

The letters after PGT tell you its purpose. These tests are not interchangeable, although more than one may sometimes be discussed for the same embryo.

PGT-A: Checking Chromosome Numbers

Most human cells contain 46 chromosomes, arranged in 23 pairs. An embryo with an extra or missing chromosome is called aneuploid. These changes can affect implantation, cause miscarriage or lead to certain chromosome conditions.

PGT-A screens the sampled cells for chromosome-number abnormalities. A doctor may discuss it with increasing maternal age or in selected cases involving previous pregnancy losses or unsuccessful treatment.

But those situations do not automatically mean you need PGT-A. Repeated miscarriage, for example, can have several causes. Testing embryos does not replace a proper assessment.

• PGT-A does not check every gene or every cause of miscarriage.
• It does not improve an embryo’s quality or repair its chromosomes.
• Routine use has not been shown to improve cumulative live birth outcomes for everyone undergoing IVF.
• Its possible value depends partly on how many embryos are available.

If you have only one embryo, ask how the result would change your treatment. There may be no embryo recommended for transfer after testing, and the benefits need to be weighed against cost, delay and limitations.

PGT-M: Looking for a Specific Inherited Condition

PGT-M is designed for a particular single-gene condition, usually after a disease-causing genetic variant has been identified. Examples include beta-thalassaemia, sickle cell disease and certain other inherited disorders.

For example, if both partners carry beta-thalassaemia variants, they may have a risk of having an affected child. A genetic counsellor can explain that risk and whether PGT-M is technically possible for their family.

This is not a ready-made panel that checks everything. The laboratory may need to develop and validate a family-specific test before treatment begins.

• Bring the original genetic reports, not only a written diagnosis.
• Reports or samples from an affected relative may be needed.
• Ask whether the test can distinguish affected, unaffected and carrier embryos.
• Check the preparation timeline before scheduling IVF medicines.

An unaffected carrier embryo is not necessarily affected by the condition. Its meaning depends on the inheritance pattern, so ask for a clear explanation rather than reading the label alone.

PGT-SR: Checking Chromosome Structure-Related Imbalances

Sometimes a person has all the necessary chromosome material, but parts are rearranged. A balanced translocation is one example. That person may be healthy yet produce eggs or sperm with an unbalanced amount of chromosome material.

PGT-SR looks for these imbalances in embryos. It may be discussed when a parental chromosome test, called a karyotype, identifies a relevant structural rearrangement.

A history of miscarriage alone does not confirm such a rearrangement. Your doctor will decide whether parental chromosome testing is appropriate.

Some PGT-SR methods cannot distinguish a chromosomally normal embryo from an embryo carrying the same balanced rearrangement as the parent. Ask the laboratory what its method can actually report.

How Does Embryo Testing Happen?

All three types of PGT testing require embryos created through IVF. They cannot be performed on eggs still inside the body or as part of an IUI cycle.

Testing usually involves a biopsy at the blastocyst stage, often around day five to seven of embryo development. A trained embryologist removes a few outer cells, which mainly contribute to the placenta.

• Eggs are collected and fertilised in the laboratory.
• Suitable embryos develop to the stage needed for biopsy.
• The sampled cells go for genetic analysis; embryos are usually frozen.
• The team reviews the results before planning a possible frozen embryo transfer.

Biopsy and freezing carry small risks, and not every embryo reaches the biopsy stage. Your doctor can explain how testing fits into IVF treatment in Lajpat Nagar.

Some laboratories recommend ICSI for particular PGT workflows to reduce contamination risk. Ask why ICSI treatment is being suggested in your case; it is not itself a genetic test.

What Can a Result Leave Uncertain?

A biopsy samples only a small part of the embryo. A result may be inconclusive, and PGT-A may report mosaicism, suggesting a mixture of cells with different chromosome findings in the sample.

A mosaic result does not describe every cell in the embryo with certainty. Decisions about such embryos need specialist genetic counselling, laboratory details and an individual review of possible outcomes.

False-positive and false-negative results are possible. PGT also cannot rule out every birth defect or condition that develops later. Prenatal screening and diagnostic testing options should still be discussed during pregnancy.

Planning Your Consultation in Delhi NCR

Before choosing between the types of PGT testing, bring previous IVF summaries, miscarriage records and any genetic reports. Ask for a written explanation of what the proposed test covers and what it cannot detect.

Pravi Global IVF is at E-3, 3rd Floor, Lajpat Nagar 2, New Delhi. Lajpat Nagar metro is on the Violet and Pink lines, making it a practical option for many couples travelling within Delhi.

People coming from Noida, Ghaziabad, Gurugram or Faridabad may use connecting metro services or drive, depending on their starting point. Allow flexibility depending on traffic, and confirm whether both partners need to attend.

Frequently Asked Questions

Does every IVF patient need PGT?

No. Your doctor will decide whether to recommend it after reviewing your history, genetic risk and available embryos. You should understand the possible benefit before consenting.

Can PGT-A replace PGT-M?

No. A normal chromosome-number result does not exclude a specific inherited single-gene condition. PGT-M needs a targeted test for that condition.

Can two PGT tests be done together?

Sometimes. The laboratory may offer combined testing when there is a clinical reason. Ask about technical feasibility, additional costs and the limitations of each component.

Does a suitable result guarantee pregnancy?

No. Implantation and pregnancy depend on several factors beyond the tested genetic finding. An embryo recommended for transfer may still not result in a live birth.

Will testing during pregnancy still be needed?

Prenatal testing options should still be discussed. Depending on the PGT indication, diagnostic confirmation through chorionic villus sampling or amniocentesis may be offered after counselling.

For a discussion about your reports at Pravi Global IVF, call +91 80091 50040 or book an appointment.