Does embryo grading have more impact on successful outcomes compared to Preimplantation Genetic Testing (PGT) tested embryos?

From the Guidelines

The current evidence suggests that PGT tested embryos do not have a proven clinical utility over embryo grading alone, and the use of PGT-P has been considered problematic by several professional societies. While embryo grading provides valuable information about an embryo's morphology and development, PGT offers direct genetic analysis that can identify chromosomal abnormalities or specific genetic disorders. However, the clinical context of IVF will affect decisions about types of PGT testing to pursue, and the success of IVF is most significantly affected by age of the egg and number of euploid embryos, which may limit the embryo selection options 1.

The implementation of PGT-P has been challenged by several groups of scientists and professional societies, including the American Society of Human Genetics, the European Society of Human Genetics, and the European Society of Human Reproduction and Embryology, all of which have called the utilization of PGT-P unethical and reject its use in clinical care 1. The clinical utility of PGT-P is affected by many environmental factors related to IVF, and additional research studies must be done to confirm both the analytical and the clinical validity of PGT-P before consideration of its use in the clinical setting 1.

Some key points to consider when evaluating the clinical utility of PGT-P include:

• The clinical context in which individuals pursue PGT-P will affect the choices they have in terms of the number and types of embryos 1.
• The clinical context in which individuals consider PGT-P will affect the risk vs benefit of this procedure and must be considered before initiating testing and included in the informed consent process 1.
• Medical professionals should make clear to those requesting PGT-P that it has not yet been shown to have clinical utility, and they may refuse to facilitate this testing based on this and the potential for harm in some clinical situations 1.

In terms of the analysis of clinical utility of PRS testing for embryo selection/PGT-P, it requires a synthesis of multiple variables: genetic testing methodology and statistical analysis, pregnant person considerations, those relating to the IVF process, and most significantly, clinical context of testing 1. Therefore, based on the current evidence, embryo grading alone may be sufficient for many patients, and the use of PGT-P should be approached with caution and careful consideration of the potential risks and benefits.

From the Research

Embryo Grading vs PGT Tested Embryos

• The grading of embryos and PGT tested embryos have different outcomes in terms of successful pregnancies and live births.
• A study published in 2022 2 found that the transfer of PGT-A abnormal embryos can result in live births, with 8 live births reported out of 57 transfer cycles.
• However, another study from 2022 3 found that patients with recurrent pregnancy loss have similar embryonic preimplantation genetic testing aneuploidy rates and IVF outcomes to infertility patients, suggesting that PGT-A may not be the sole determining factor for successful outcomes.
• A 2021 study 4 found that PGT-A can improve clinical outcomes in ICSI cycles, particularly in patients with repeated implantation failure, but the addition of ERA testing did not provide further benefits.
• Another study from 2021 5 found that PGT-A was associated with improved live birth rates in women with recurrent pregnancy loss undergoing frozen embryo transfer, particularly in older women.
• A 2019 study 6 found that PGT-A can improve live birth rates in IVF cycles for patients with advanced maternal age, repeat implantation failure, and idiopathic recurrent miscarriage.

Comparison of Outcomes

• The studies suggest that while PGT-A can improve outcomes in certain patient populations, the grading of embryos also plays a crucial role in determining successful pregnancies and live births.
• The transfer of PGT-A abnormal embryos can still result in live births, highlighting the importance of considering multiple factors when evaluating embryo viability.
• Further research is needed to fully understand the relationship between embryo grading, PGT-A, and successful outcomes in IVF cycles.