PGT-A Testing, PGT-M, PGT-SR: Which One and When

Your clinic has put PGT on the consent form, your insurance does not cover it, and the cost is somewhere between three and six thousand dollars before per-embryo biopsy fees. You want to know whether the evidence for PGT-A testing is as strong as the marketing, which of the three tests applies to you, and whether to say yes when you sign.

PGT is not one test. It is three different tests that get bundled into a single acronym on most consent forms, and confusing them leads to thousands of dollars spent on the wrong test for the wrong reason. PGT-A testing screens chromosome count for everyone considering it as an add-on. PGT-M tests for a known single-gene disease in your family. PGT-SR tests for a known structural rearrangement in one parent's karyotype. The three letters mean three different jobs, three different price tags, and three different conversations with your reproductive endocrinologist (RE).

This post walks through what each test does, how the embryo biopsy works, what the published evidence actually shows, and when I think the test is worth the money. I do not push PGT-A on every patient. The 2019 STAR trial made me much more selective about who I recommend it to, and the 2021 NEJM trial out of China reinforced that selectivity¹². The decision is yours and your RE's. My job is to make sure you walk into that conversation knowing what you are buying.

Why PGT matters right now

PGT changed what the word "euploid" means clinically. Before next-generation sequencing was affordable, an embryologist graded an embryo by morphology under a microscope and the transfer decision was a coin flip with extra steps. Now, in a PGT cycle, the lab can tell you with high accuracy whether the chromosome count of a five-cell trophectoderm biopsy is normal or abnormal. That sounds like a clean win, and on a per-transfer basis it is. Miscarriage rate drops. Time-to-pregnancy drops.

The harder question is whether PGT-A increases the number of babies born from a given retrieval. The published evidence on that is mixed. The Munné STAR trial, a multicenter randomized clinical trial in good-prognosis patients published in Fertility and Sterility in 2019, found no improvement in cumulative live birth rate per cycle started when PGT-A was added to morphology selection¹. The Yan trial in NEJM in 2021 reached a similar conclusion in a Chinese cohort of women aged 20 to 37 with three or more blastocysts: live birth rates per intended retrieval were similar with and without PGT-A².

Then there is the biopsy itself. At blastocyst stage, on day 5, 6, or 7 of culture, an embryologist removes five to ten cells from the trophectoderm, the outer layer that becomes placenta, not the inner cell mass (ICM) that becomes the baby. The embryo cost of the biopsy is small but not zero. Most clinics report no measurable harm; some studies of inexperienced labs show a hit to implantation. Choose a clinic with a high-volume embryology team and the biopsy risk is essentially nominal.

The three PGT tests in plain English

The three letters do three different things. If you remember nothing else from this post, remember the distinction. Your RE may not always slow down to draw it out.

PGT-A: aneuploidy screening

PGT-A screens chromosome count. The lab looks at the biopsied cells and reports whether the embryo is euploid (the right number of chromosomes, 46), aneuploid (extra or missing chromosomes), or mosaic (a mixed result with both normal and abnormal cells in the biopsy). This is the test most people mean when they say "PGT," and it is the one the marketing brochure is talking about.

PGT-A is considered as an add-on for couples in specific situations: advanced maternal age, generally over 37, where the proportion of aneuploid embryos rises sharply; recurrent pregnancy loss, defined as two or more clinical miscarriages; recurrent implantation failure (RIF); prior aneuploid pregnancy or trisomy diagnosis. The American Society for Reproductive Medicine (ASRM) committee opinion is careful to frame PGT-A as an option to discuss with patients, not a default for every IVF cycle⁷. The European Society of Human Reproduction and Embryology (ESHRE) PGT Consortium good-practice recommendations are similarly measured⁵.

PGT-M: monogenic disease testing

PGT-M tests for a specific inherited single-gene disease. Cystic fibrosis. Sickle cell disease. Huntington's disease. BRCA1 and BRCA2 cancer-predisposition mutations. Tay-Sachs. Fragile X. Spinal muscular atrophy. The list is long and the conversation begins with a genetic counselor, not with your RE. PGT-M is mandatory, not optional, if you and your partner are confirmed carriers of an autosomal recessive disease, or if one of you carries a dominant mutation you do not want to pass to a child.

The mechanics are different from PGT-A. PGT-M requires probe development, a custom genetic test built around your specific family mutation, using DNA samples from both partners and often an affected relative. Probe development takes four to eight weeks before retrieval. Plan ahead. You cannot decide to add PGT-M after retrieval has happened. Some clinics will run PGT-A and PGT-M on the same biopsy; ask in advance.

PGT-SR: structural rearrangements

PGT-SR tests for known balanced translocations, Robertsonian translocations, or inversions in one parent's karyotype. Most couples discover the indication after a recurrent miscarriage workup that includes parental karyotyping. A balanced translocation in one parent is reproductively silent (the carrier is usually healthy), but the embryos can inherit unbalanced versions that fail to implant or miscarry early.

Like PGT-M, PGT-SR uses customized testing rather than off-the-shelf NGS. The probe identifies whether a given embryo carries the balanced rearrangement (acceptable for transfer in most counseling models, since the resulting child would be a healthy carrier like the parent), an unbalanced version (not transferred), or no rearrangement at all (also acceptable).

How the embryo biopsy and PGT testing actually work

I want you to be able to picture this. Most patients never see the embryology lab and the procedure feels abstract until something goes wrong.

Embryos that fertilize and divide normally reach blastocyst stage on day 5, 6, or sometimes day 7 of culture. A blastocyst has two visible parts: the inner cell mass (ICM), a tight cluster of cells that becomes the fetus, and the trophectoderm (TE), the surrounding outer layer that becomes placenta. The biopsy is performed on the trophectoderm, not the ICM. Five to ten cells are removed using a laser-assisted technique that opens a small breach in the zona pellucida (the outer shell) so the embryologist can extract cells with a fine pipette.

Same-day vitrification follows. Vitrification is ultra-rapid freezing in liquid nitrogen: the embryo passes through cryoprotectant solutions and is plunged into nitrogen so quickly that ice crystals do not have time to form. PGT does not work on fresh-transfer cycles for one practical reason: the genetics results take one to three weeks to come back, and a blastocyst cannot wait that long in the uterus. Every PGT cycle is a frozen embryo transfer (FET) cycle by design.

The biopsied cells travel to a genetics lab. For PGT-A, the lab amplifies the DNA from those five-to-ten cells using whole-genome amplification, then sequences it with next-generation sequencing (NGS). NGS is sensitive enough to detect chromosome count for each of the 23 chromosome pairs, and modern platforms can also flag mosaicism, that mixed result where some cells in the biopsy look normal and others do not. For PGT-M and PGT-SR, the lab uses the family-specific probe developed weeks earlier, often combined with haplotype analysis using parental DNA to confirm which embryos carry the mutation and which do not.

Results come back to your clinic in one to three weeks depending on the lab. You will see a report with one row per biopsied embryo. The transfer happens in a later FET cycle, after the lining is prepared with estrogen and progesterone, using the euploid embryo (or, in some carefully counseled cases, a mosaic) the team and you have selected.

Reading a PGT-A report at a high level

A full deep-dive on PGT-A results lives in the next post. Here is the orientation you need to follow the lab report when it arrives.

• Euploid: 46 chromosomes, no detected aneuploidies. The standard recommendation is to transfer.
• Aneuploid: one or more whole-chromosome gains or losses. Almost always not transferred. Most aneuploidies are incompatible with viable pregnancy or compatible only with severe conditions.
• Mosaic: the biopsy returned both normal and abnormal cells, reported as a percentage of cells abnormal and with the chromosome involved named. This category is the genuinely hard one and has a dedicated decision-frame post.
• No result / inconclusive: insufficient DNA, contamination, or technical failure. You can re-biopsy at additional cost or transfer the embryo as untested. Both are reasonable in specific cases.

Five to ten percent of biopsied blastocysts return mosaic results, depending on the lab and the reporting thresholds used³. That is high enough that you should expect to face the question, especially if you are biopsying more than a handful of embryos.

What the evidence actually shows

This is the part of the conversation that often gets compressed in a fifteen-minute clinic consult, so I want to slow it down.

The STAR trial published by Munné and colleagues in 2019 enrolled 661 good-prognosis patients across multiple US centers in a randomized comparison of PGT-A plus single euploid frozen embryo transfer versus single frozen embryo transfer selected by morphology alone¹. The primary endpoint was ongoing pregnancy rate per cycle started. In the intention-to-treat analysis, PGT-A did not improve ongoing pregnancy rates. In a subgroup of women aged 35 to 40 with at least two blastocysts, PGT-A did improve outcomes, and that subgroup signal is part of why I still recommend PGT-A selectively for older patients.

The Yan trial published in NEJM in 2021 enrolled 1,212 women aged 20 to 37 with three or more good-quality blastocysts at three Chinese centers, randomized to PGT-A versus conventional morphology selection². Live birth rate per intended retrieval was 77.2 percent with PGT-A and 81.8 percent without. The conclusion was that PGT-A did not improve cumulative live birth in a good-prognosis younger cohort with a meaningful blast yield.

What both trials agree on, and what the broader registry literature confirms, is that PGT-A reduces miscarriage rate per transfer and shortens time to live birth by sorting against aneuploid embryos earlier in the process. If you have aneuploid embryos in your cohort and you transfer them blind, some of them will implant, develop briefly, and miscarry. PGT-A spares you those transfers. What it does not do, on the available evidence, is increase the number of babies born from a given egg cohort. The cumulative-live-birth math is roughly the same whether you sort with PGT-A or you transfer in morphology order and let the body sort.

I tell patients this directly: PGT-A buys you faster time-to-pregnancy and a lower miscarriage rate per transfer. It does not buy you more babies. Whether that trade-off is worth three to six thousand dollars depends on your age, your embryo numbers, and your tolerance for the emotional weight of failed transfers and early losses.

When PGT-A testing makes sense

The published evidence and my own practice converge on a short list of indications where PGT-A pays off.

• Advanced maternal age, generally over 37 to 38. The proportion of aneuploid embryos rises steeply with maternal age. At 42, the majority of biopsied blastocysts are aneuploid. PGT-A lets you avoid weeks of preparation for a transfer that has very low odds.
• History of recurrent pregnancy loss, defined as two or more clinical losses. Most early miscarriages are aneuploid. PGT-A can interrupt that cycle.
• Prior aneuploid pregnancy or trisomy diagnosis, particularly if confirmed by products-of-conception karyotyping or prenatal diagnostic testing.
• A meaningful embryo cohort to sort: Four or more blastocyst-quality embryos gives the test something to do. With one or two embryos, the sorting question becomes academic: you will transfer what you have.
• Recurrent implantation failure, defined variably but generally two or more failed euploid-grade transfers in a younger patient. PGT-A here is sometimes part of a broader workup that includes endometrial receptivity testing.

When PGT-A may not help, and may hurt

Some situations argue against the add-on.

• Very low embryo numbers, one or two blastocysts. The biopsy itself, while low-risk, is not zero-risk in an inexperienced lab. Discarding a mosaic that might have been your only viable embryo is a real outcome.
• Young patients with high blast yield: The Yan trial population. Most embryos in that group are euploid anyway, and the cumulative live birth math suggests morphology selection is comparably effective.
• Cost as a cycle-limiting factor: If paying for PGT-A means you can only afford one retrieval instead of two, the math probably does not favor PGT-A. Two retrievals with morphology selection will likely outperform one retrieval with PGT-A.

When you need PGT-M or PGT-SR

PGT-M and PGT-SR are different conversations entirely. These are not optional add-ons. For some couples, they are the reason IVF is on the table in the first place.

• A known monogenic disease in one or both partners, confirmed by genetic testing, with an established family mutation. Cystic fibrosis carrier-couples. Hemoglobinopathy carrier-couples. BRCA-positive future parents who want to avoid passing the mutation forward.
• Both partners confirmed carriers of an autosomal recessive disease via expanded carrier screening.
• One partner with a dominant disease with risk of transmission, particularly adult-onset conditions like Huntington's.
• One partner with a known balanced translocation, Robertsonian translocation, or inversion identified on parental karyotype, usually after a recurrent miscarriage workup.

The pathway for PGT-M and PGT-SR starts with a genetic counselor, not with the RE. The counselor will confirm the mutation, coordinate probe development, and walk you through the disclosure and reporting decisions before the cycle begins.

What PGT-A, PGT-M, and PGT-SR cost

These are US ranges as of 2026. Your clinic and your lab will vary.

• PGT-A: USD 3,000 to 6,000 for the lab platform fee, plus USD 200 to 500 per embryo biopsied at the clinic. Rarely insurance-covered. Some employers with fertility benefits include PGT-A; check your benefits document.
• PGT-M: USD 4,000 to 8,000 for probe development, plus per-embryo testing at similar ranges to PGT-A. Sometimes partly insurance-covered with a genetic counselor letter documenting indication.
• PGT-SR: similar to PGT-M ranges, with the probe customized to the parental rearrangement.

A typical PGT-A cycle adds USD 4,000 to 8,000 to a retrieval that is already costing USD 15,000 to 25,000. That is real money. Ask for a written quote that breaks out platform fee, per-embryo cost, and shipping fees to the genetics lab.

What to ask your RE and your genetic counselor

Walk into the consult with a list. I have lost count of how many patients have told me they wished they had asked specific questions before signing the consent.

• Given my age, AMH, antral follicle count, and embryo yield in past cycles, what does the PGT-A evidence say about expected benefit for someone like me?
• What is your clinic's no-result or inconclusive rate per biopsy?
• How does your clinic handle mosaic results? Do you have a written mosaic transfer policy and outcome data?
• For PGT-M or PGT-SR: do we have the probe ready and validated before retrieval starts?
• What is your clinic's discard rate, meaning embryos called aneuploid or otherwise not recommended for transfer?
• Do you re-biopsy no-result embryos, transfer them as untested, or discard them?
• Will sex chromosome information be disclosed by default, on request, or not at all?

The answers will vary clinic to clinic. The willingness to answer in plain numbers, without hedging, is itself a signal about the clinic.

What this means for your transfer decision

Here is how I summarize PGT for patients. PGT-A testing is a probability-sharpening tool. It tells you which embryos in your cohort are most likely to result in ongoing pregnancy if transferred. It does not predict implantation perfectly. Euploid transfers still fail. Some mosaic transfers succeed. Morphology grade still matters as a tiebreaker among euploid embryos.

PGT-M and PGT-SR are different. Those are diagnostic tests for known family conditions, not screening tests, and the conversation is about which embryos carry a specific risk you have chosen to avoid.

If you are reading this before your retrieval, ask your RE for the conversation in writing: what they recommend for you specifically, why, and what the cost will be. If you are reading this after retrieval with embryos already biopsied and a report in hand, the next post in this section walks through how to read the report row by row.

What's next

• If your retrieval is upcoming and you're deciding whether to add PGT-A: pgt-a-results-meaning so you know what the report will look like
• If your PGT-A report came back with a mosaic result: should-transfer-mosaic-embryo
• If you're scheduling the FET cycle after PGT: embryo-grading-explained for how grade and ploidy interact in transfer selection
• If a euploid transfer failed and you're trying to understand why: failed-ivf-decoding-next

Sources

1. Munné S, Kaplan B, Frattarelli JL, et al. Preimplantation genetic testing for aneuploidy versus morphology as selection criteria for single frozen-thawed embryo transfer in good-prognosis patients: a multicenter randomized clinical trial (STAR). Fertility and Sterility 2019;112(6):1071-1079.e7. https://doi.org/10.1016/j.fertnstert.2019.07.1346
2. Yan J, Qin Y, Zhao H, et al. Live Birth with or without Preimplantation Genetic Testing for Aneuploidy. New England Journal of Medicine 2021;385(22):2047-2058. https://doi.org/10.1056/NEJMoa2103613
3. Practice Committee and Genetic Counseling Professional Group of the American Society for Reproductive Medicine. Clinical management of mosaic results from preimplantation genetic testing for aneuploidy (PGT-A): a committee opinion. Fertility and Sterility 2020;114(2):246-254. https://doi.org/10.1016/j.fertnstert.2020.05.014
4. Preimplantation Genetic Diagnosis International Society (PGDIS). Position Statement on the Transfer of Mosaic Embryos. 2021. https://www.pgdis.org/
5. ESHRE PGT Consortium and SIG-Embryology Biopsy Working Group. ESHRE PGT Consortium good practice recommendations for the detection of structural and numerical chromosomal aberrations and the use of preimplantation genetic testing for aneuploidy (PGT-A). Human Reproduction Open 2020;2020(3):hoaa017. https://doi.org/10.1093/hropen/hoaa017
6. Capalbo A, Poli M, Rienzi L, et al. Mosaic human preimplantation embryos and their developmental potential in a prospective, non-selection clinical study. American Journal of Human Genetics 2021;108(12):2238-2247. https://doi.org/10.1016/j.ajhg.2021.11.002
7. Practice Committee of the American Society for Reproductive Medicine and Practice Committee for the Society for Assisted Reproductive Technology. The use of preimplantation genetic testing for aneuploidy: a committee opinion. Fertility and Sterility 2024;121(6):1003-1010.