Treatment guide
Preimplantation genetic testing (PGT)
Biopsying a few cells from an embryo to screen for chromosomal or genetic conditions before transfer.
Written and reviewed by the MyBabyBridge editorial team · Last reviewed · 3 sources · General information, not medical advice. Our editorial standards
What it is
PGT takes a small biopsy of cells from the outer layer of a blastocyst and tests them. PGT-A screens for the correct number of chromosomes, PGT-M tests for a specific inherited single-gene condition, and PGT-SR is used when a parent carries a structural chromosome rearrangement. PGT-M and PGT-SR have clear indications. PGT-A is the contested one. It aims to avoid transferring embryos unlikely to succeed, but ASRM says its value as a routine screening test for all IVF patients has not been demonstrated, and the UK regulator (HFEA) rates it red for improving the chance of having a baby for most patients, because it often reduces the number of embryos available to transfer. HFEA rates it green for reducing miscarriage, a benefit ASRM considers unclear. Mosaic results also create genuinely difficult decisions.
Who it is usually for
Indicated when a parent carries a known single-gene condition or chromosomal rearrangement. PGT-A is offered more broadly, for example for older patients, recurrent pregnancy loss, or repeated implantation failure, where the evidence of benefit is limited.
Unfamiliar term? See the fertility glossary.
What happens, step by step
- Step 1
Culture to blastocyst
Only embryos reaching the blastocyst stage can be biopsied, so some cycles produce nothing to test.
- Step 2
Biopsy
A few cells are removed from the trophectoderm, the part that becomes the placenta.
- Step 3
Freeze and test
Embryos are frozen while the sample is analyzed by an external genetics laboratory, usually over one to three weeks.
- Step 4
Results and transfer
Results are discussed, and a suitable embryo is transferred in a later frozen cycle.
Time and cost
How long it takes
Adds one to three weeks and converts the cycle into a frozen transfer cycle.
What it typically costs
Typically billed as a biopsy fee plus a testing fee per embryo, so the total rises with the number of embryos tested, on top of the frozen transfer cycle that testing requires.
Prices vary widely by clinic and region. Get an itemised estimate in writing — see the IVF cost guide.
Risks and limits
- A cycle can end with no embryos suitable for biopsy or transfer
- Embryos reported as abnormal or mosaic may be discarded even though some could have led to a healthy baby, so PGT-A can lower the overall chance of a live birth from a cycle for some patients
- The time to a live birth may be longer rather than shorter
- Mosaic and inconclusive results are common and hard to act on
- The biopsy samples the placental cell line, not the fetus, so results are not diagnostic of the baby
- Additional cost that is usually not refunded if the cycle fails
What to ask your clinic
- What specifically would PGT change about my treatment plan?
- What is your rate of mosaic and no-result reports?
- How do you counsel patients about transferring a mosaic embryo?
- Which genetics laboratory do you use, and what is their turnaround?
- What is the total added cost for my expected number of embryos?
Ask for the answers in writing, alongside itemised costs.
Sources
- The Use of Preimplantation Genetic Testing for Aneuploidy: A Committee Opinion (2024) — American Society for Reproductive Medicine
- Pre-implantation Genetic Testing for Aneuploidy (PGT-A): Evidence Ratings — Human Fertilisation and Embryology Authority
- Assisted Reproductive Technology — MedlinePlus, U.S. National Library of Medicine
Thinking about Preimplantation genetic testing (PGT)?
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