Understanding Abnormal PGT-A Results

What Do Abnormal PGT-A Results Mean?

PGT-A evaluates chromosome copy number in cells sampled from an embryo’s trophectoderm, the portion that typically develops into the placenta. Results provide information about whether the sampled cells appear to contain the expected number of chromosomes.

An abnormal PGT-A result generally means that the chromosome findings differed from the expected euploid pattern. Depending on the result, an embryo may be classified as aneuploid, mosaic or receive another laboratory-specific designation.

Types of PGT-A Results

PGT-A reports can include several categories:

• Euploid: The sampled cells show the expected number of chromosomes.
• Aneuploid: The sampled cells show one or more chromosome gains or losses.
• Mosaic: The sample contains a mixture of cells with different chromosome findings.
• Segmental finding: A gain or loss involves part of a chromosome rather than an entire chromosome.
• Inconclusive or no result: The laboratory was unable to obtain a definitive result from the sample.

PGT-A is a screening test rather than a diagnostic test of a pregnancy. Your physician and, when appropriate, a genetic counselor can help explain what a particular embryo result may mean for treatment decisions.

How PGT-A Results Are Interpreted

PGT-A results are interpreted embryo by embryo, but the complete group of results can also provide useful information about an IVF cycle. Your physician may consider how many embryos reached the blastocyst stage, how many were available for testing and how those embryos were classified.

Age is particularly relevant because embryo aneuploidy becomes more common as egg age increases. As a result, finding some aneuploid embryos during PGT-A is not unusual, and the proportion of euploid embryos can vary substantially between patients and even between IVF cycles in the same patient.

Mosaic results require additional nuance because they reflect a mixture of chromosome signals within the biopsy sample. The specific chromosome finding, laboratory classification and other details of the report may be relevant when considering whether a mosaic embryo could be appropriate for transfer. Genetic counseling may be recommended before making that decision.

PGT-A results should also be understood within the limitations of the test. PGT-A screens cells sampled from the embryo; it does not diagnose every genetic condition or guarantee implantation, pregnancy or the health of a future pregnancy. Your Spring Fertility physician can help place the results within the broader context of embryo quality, reproductive history and your family-building goals.

What Happens After Abnormal PGT-A Results?

What happens after abnormal PGT-A results depends on the specific findings and the other embryos available from your IVF cycle. If some embryos are euploid, your physician may discuss whether one of those embryos is appropriate to consider for transfer. If results include mosaic embryos, additional counseling may be useful before decisions are made about those embryos.

When all embryos tested are reported as aneuploid, or when no euploid embryos are available, your physician can review the entire IVF cycle to understand the result in context. Egg age, ovarian response, the number of mature eggs, fertilization, blastocyst development and the number of embryos tested all influence the opportunity to obtain a euploid embryo.

Depending on the specific PGT-A findings, consultation with a genetic counselor may also be recommended. Genetic counseling can help explain chromosome findings, mosaic results, limitations of testing and considerations that may be relevant when making decisions about embryos.

Your Spring Fertility physician can use the results of the cycle to discuss individualized next steps. These may include proceeding with an available embryo, considering another IVF cycle or obtaining additional genetic guidance before making a treatment decision.