IVF Genetic Testing (PGT)

How genetic testing fits into your IVF cycle

The IVF cycle proceeds as standard through egg retrieval, fertilization, and embryo culture to the blastocyst stage. On day 5 or 6, a small number of cells are biopsied from each embryo and sent to a genetics laboratory for chromosomal analysis. Embryos are frozen while results are pending, which typically takes one to two weeks.

Only chromosomally normal (euploid) embryos are then transferred in a frozen embryo transfer cycle. Aneuploid embryos are typically not transferred. Some embryos return a mosaic result, meaning they contain a mix of normal and abnormal cells. How clinics handle mosaic embryos varies — ask about your clinic's approach before testing begins.

Who PGT is recommended for

PGT-A is most commonly recommended in the following situations:

1. Two or more failed IVF cycles
2. Recurrent pregnancy loss
3. Advanced maternal age (typically 35 and over)
4. Severe male factor infertility
5. Known chromosomal rearrangements in either partner

For younger patients with a good prognosis and no history of failed cycles, the benefit of adding PGT-A is less certain. Testing may not improve cumulative live birth rates compared to transferring untested embryos over multiple cycles. Ask your specialist whether it is indicated for your situation before adding it to your protocol.

Types of preimplantation genetic testing

PGT-A screens for chromosomal aneuploidies — missing or extra chromosomes. It is the most commonly performed type and applies to the situations listed above.

PGT-M tests for a specific single-gene disorder where one or both partners are carriers — for example, cystic fibrosis, spinal muscular atrophy, or BRCA-related mutations. It requires pre-cycle preparation and a longer lead time than PGT-A.

PGT-SR screens for structural chromosomal rearrangements in patients who carry a known translocation. The laboratory process and preparation timelines differ from both PGT-A and PGT-M.

Your fertility specialist and genetic counselor will advise which type is appropriate based on your clinical and family history.

What a euploid result does and does not mean

A euploid embryo has the correct number of chromosomes, removing one significant cause of implantation failure. It does not mean the embryo will implant successfully. Uterine factors, endometrial receptivity, and aspects of embryo quality that chromosomal screening cannot detect all affect outcome.

Some patients complete a full cycle and find they have no transferable embryos after testing. This is more likely when stimulation produced a small number of eggs to begin with — a possibility worth factoring into your planning if your ovarian reserve is limited.

Questions to ask before adding PGT to your protocol

Confirm the following with your clinic before committing to genetic testing:

1. Is the biopsy and analysis performed in-house or sent to an external laboratory?
2. What is the turnaround time for results?
3. Which panels are available — PGT-A only, or PGT-M and PGT-SR as well?
4. How does the clinic handle mosaic embryo results?
5. Is pricing per embryo tested or per cycle?