What Are PGT-A, PGT-M, and PGT-SR?

If you are considering IVF and have heard about PGT-A, PGT-M, and PGT-SR, you may be wondering which test you need or whether you need PGT at all. These tests examine embryos for different genetic or chromosomal concerns before embryo transfer. Understanding the differences can help you have a more informed discussion with your fertility specialist.

Preimplantation genetic testing (PGT) is performed as part of an IVF cycle and involves examining cells from an embryo before it is transferred to the uterus. The three main types of PGT- PGT-A, PGT-M, and PGT-SR look for different problems.

At Fertility & Wellbeing Center in Dubai, PGT is part of an integrated approach that combines reproductive medicine, embryology, genetic guidance, and psychological support. 

What Is PGT and Why Is It Used in IVF?

Preimplantation genetic testing (PGT) is a laboratory testing method used to examine embryos created through in vitro fertilization (IVF). IVF is a fertility treatment in which eggs and sperm are combined in a laboratory to create embryos.

When an embryo develops to the blastocyst stage, usually around day 5 or 6, a small sample of cells can be taken for genetic analysis. The embryo is generally frozen while testing is completed, and the results can then help your fertility team plan which embryo may be appropriate for transfer.

PGT is not one single test. The type of testing depends on what your doctor is trying to identify:

• PGT-A: looks for an abnormal number of chromosomes.
• PGT-M: looks for a specific inherited single-gene condition.
• PGT-SR: looks for certain structural chromosome rearrangements.

These tests are not interchangeable. Your medical history, family history, previous pregnancy outcomes, genetic testing, and IVF circumstances help determine whether a particular type of PGT may be appropriate.

Does everyone undergoing IVF need PGT?

No. PGT is not automatically required for every IVF patient.

PGT-A, in particular, is considered on an individual basis rather than being a universal part of IVF. PGT-M and PGT-SR are generally considered when there is a known genetic or chromosomal concern that could affect the embryos.

Your fertility specialist may recommend genetic counselling before deciding whether testing could be useful in your specific situation.

PGT-A, PGT-M, and PGT-SR: What Is the Difference?

The easiest way to understand the three tests is to think about what each one is looking for.

Test	What it checks	When it may be considered
PGT-A	Number of chromosomes	Certain IVF patients where chromosome-number abnormalities are a concern
PGT-M	A specific single-gene condition	Known inherited genetic condition in the family
PGT-SR	Chromosome structure	Known translocation, inversion, or other structural rearrangement

Although all three involve testing embryo cells, the genetic question being asked is different.

What Is PGT-A?

PGT-A stands for Preimplantation Genetic Testing for Aneuploidy.

Aneuploidy means that an embryo has an abnormal number of chromosomes—for example, an extra or missing chromosome.

Most human embryos have 23 pairs of chromosomes. PGT-A screens embryos to identify chromosome-number abnormalities. Some aneuploid embryos are associated with implantation failure, miscarriage, or certain chromosome conditions.

Who might discuss PGT-A with a fertility specialist?

PGT-A may be considered in situations such as:

• Recurrent pregnancy loss
• Previous unsuccessful IVF treatment
• Certain previous pregnancies affected by chromosome abnormalities
• Increasing maternal age
• Situations where embryo selection is an important part of treatment planning

However, age alone does not automatically mean you need PGT-A. The potential benefits and limitations should be discussed with your fertility specialist.

What can PGT-A tell you?

PGT-A can help classify embryos according to whether the tested cells show a typical or abnormal chromosome number.

Results can sometimes also identify mosaic embryos. Mosaicism means that different cells within the embryo may have different chromosome findings. Decisions about mosaic embryos can be complex and should be made with an experienced fertility team and, where appropriate, genetic counselling. 

Importantly, PGT-A is a screening test, not a guarantee of a healthy baby. It does not test for every possible genetic or developmental condition. 

What Is PGT-M?

PGT-M stands for Preimplantation Genetic Testing for Monogenic Disorders.

“Monogenic” means a condition caused by a change in a single gene.

Unlike PGT-A, which looks broadly at chromosome numbers, PGT-M is designed to look for a specific known genetic condition.

Examples can include inherited conditions such as:

• Cystic fibrosis
• Sickle cell disease
• Spinal muscular atrophy
• Certain forms of muscular dystrophy
• Other known single-gene disorders

PGT-M may be discussed when one or both prospective parents have a known genetic condition, are carriers of a particular condition, or have a family history suggesting an increased reproductive risk. 

How does PGT-M work?

Because PGT-M is designed around a specific genetic condition, the fertility and genetics team needs detailed information about the genetic variant involved.

The general process includes:

1. Genetic assessment – Your genetic history and relevant test results are reviewed.
2. IVF treatment – Eggs are collected and fertilised to create embryos.
3. Embryo development – Embryos are cultured in the laboratory until the blastocyst stage.
4. Embryo biopsy – A small number of cells are collected for testing.
5. Genetic analysis – The sample is tested for the specific condition.
6. Embryo planning – Your fertility team discusses which embryos may be suitable for transfer.

Not every genetic condition can necessarily be tested using PGT-M, so specialist assessment and laboratory preparation are important.

Does PGT-M guarantee that a baby will not have a genetic condition?

No.

PGT-M is designed to identify embryos with respect to the specific genetic condition being tested, but it does not screen for every possible genetic or medical condition. Prenatal testing may still be recommended during pregnancy to confirm PGT findings. 

What Is PGT-SR?

PGT-SR stands for Preimplantation Genetic Testing for Structural Rearrangements.

This test is different from PGT-A because it focuses on the structure of chromosomes, rather than simply whether there are too many or too few chromosomes.

A structural chromosome rearrangement can include:

• Translocation – when genetic material moves from one chromosome to another.
• Inversion – when a section of a chromosome breaks off and reverses direction.
• Other structural changes involving chromosome segments.

A person can sometimes carry a balanced chromosome rearrangement without having obvious health problems. However, during reproduction, the rearrangement can result in embryos with an unbalanced amount of genetic material. This may contribute to implantation problems or pregnancy loss.

Who may need PGT-SR?

Your fertility specialist or genetic counsellor may discuss PGT-SR if:

• You or your partner has a known chromosomal translocation.
• You or your partner has a known inversion.
• There is a history of recurrent miscarriage associated with a chromosome rearrangement.
• Previous genetic or chromosome testing has identified a structural abnormality.

PGT-SR therefore has a very different purpose from routine chromosome-number screening.

How Does PGT Work During an IVF Cycle?

Although PGT-A, PGT-M, and PGT-SR answer different genetic questions, the overall laboratory process is broadly similar.

Step 1: Fertility and genetic assessment

Before treatment, your fertility specialist reviews your reproductive history, previous IVF or pregnancy outcomes, family history, and relevant genetic investigations.

For PGT-M or PGT-SR, existing genetic or chromosome reports may be particularly important.

Step 2: IVF and fertilisation

Your eggs are collected during an IVF cycle and fertilised with sperm in the laboratory.

Depending on your circumstances, your fertility team may recommend ICSI (intracytoplasmic sperm injection), a technique in which a single sperm is injected directly into an egg.

Step 3: Embryo development

The embryos are monitored as they develop in the laboratory.

Those that reach the blastocyst stage may be considered for biopsy.

Step 4: Embryo biopsy

A small number of cells are carefully removed from the embryo for genetic analysis.

The biopsy sample is sent for the relevant genetic testing, depending on whether the treatment involves PGT-A, PGT-M, PGT-SR, or a combination.

Step 5: Embryo freezing

Because genetic analysis takes time, embryos are commonly cryopreserved while results are being processed. Almond Blossoms provides embryo freezing and storage as part of its fertility services.

Step 6: Results and treatment planning

Your fertility specialist reviews the results with you and explains which embryos may be suitable for transfer.

This is an important stage because genetic test results can sometimes be more complicated than simply “normal” or “abnormal.” For example, PGT-A can identify mosaic results that require careful interpretation.

Which PGT Test Is Right for You?

There is no single PGT test that is best for everyone.

Your fertility specialist may consider several factors before recommending testing.

Your age and reproductive history

Age can influence the likelihood of chromosome abnormalities in embryos, while previous miscarriages or unsuccessful IVF cycles may also be relevant to treatment planning.

However, PGT-A should be considered in the context of your overall fertility picture rather than based on age alone.

Your family genetic history

If you or your partner has a known inherited condition or if genetic testing identifies a relevant carrier status, PGT-M may be considered.

Your chromosome results

If you have been diagnosed with a structural chromosome rearrangement such as a translocation or inversion, PGT-SR may be relevant.

Your previous pregnancy history

Repeated pregnancy loss or a previous pregnancy affected by a chromosome condition may lead your specialist to recommend additional genetic evaluation.

Your emotional wellbeing

Genetic testing can bring reassurance, but it can also create difficult decisions, particularly when there are few embryos available, inconclusive findings, or results that are difficult to interpret.

That is why genetic information should be explained carefully rather than presented as a simple “good” or “bad” result.

At Almond Blossoms, fertility treatment is integrated with psychological and counselling support, giving patients the option to address the emotional impact of fertility and genetic decisions alongside their medical care.

Is PGT-A Better Than PGT-M or PGT-SR?

No. They are designed for different purposes.

It is more useful to ask:

“Which genetic question needs to be answered in my situation?”

For example:

• If the concern is chromosome number, PGT-A may be relevant.
• If the concern is a known single-gene condition, PGT-M may be relevant.
• If the concern is a known chromosome structural rearrangement, PGT-SR may be relevant.

In some situations, more than one type of testing may be considered. The decision should be personalised after reviewing your medical and genetic information.

PGT should also not be presented as a guarantee of IVF success. Even when an embryo has reassuring PGT findings, implantation and pregnancy depend on many other biological factors.