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Real-Time Embryo Imaging Challenges Traditional IVF Screening Methods
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New research utilizing advanced real-time imaging techniques is casting doubt on the accuracy of preimplantation genetic testing for aneuploidy (PGT-A), a common procedure used during in vitro fertilization (IVF). The findings suggest that embryos previously deemed genetically normal by PGT-A may, in fact, harbor chromosomal abnormalities, potentially impacting implantation rates and pregnancy outcomes.
The Current Landscape of PGT-A
PGT-A involves removing a few cells from an embryo (typically on day 5 or 6 of advancement, the blastocyst stage) and analyzing its chromosomes for an accurate number (23 pairs). The goal is to identify embryos with aneuploidy - an abnormal number of chromosomes - which are less likely to implant successfully or result in a healthy pregnancy. PGT-A is often offered to women over 35,those with recurrent miscarriages,or those with a family history of chromosomal disorders. Though, the cost of PGT-A can add several thousand dollars to an IVF cycle.
The global assisted reproductive technology (ART) market, which includes IVF and PGT-A, was valued at USD 36.2 billion in 2023
and is projected to reach USD 67.08 billion by 2032
, according to a report by Polaris Market research. This growth underscores the increasing reliance on these technologies, making the accuracy of PGT-A paramount. Polaris Market Research - Assisted Reproductive Technology Market
New Imaging Reveals Chromosomal Mosaicism
Recent advancements in time-lapse imaging and artificial intelligence (AI) are allowing scientists to observe embryo development in unprecedented detail. These technologies reveal that many embryos previously classified as chromosomally normal by PGT-A actually exhibit mosaicism – a mixture of cells with different chromosomal compositions within the same embryo. This means that the few cells biopsied for PGT-A may not accurately represent the genetic makeup of the entire embryo.
Researchers at multiple institutions, including the Institute for Reproductive Medicine and Science at Rutgers New Jersey Medical School, have presented data suggesting that a significant proportion of embryos deemed euploid (having the correct number of chromosomes) by PGT-A are, in fact, mosaic. This discovery challenges the fundamental assumption that PGT-A provides a definitive assessment of embryo genetic health.
Implications for IVF success Rates
The presence of mosaicism raises questions about the impact of PGT-A on IVF success rates. If embryos with mosaicism are discarded based on inaccurate PGT-A results, couples may be missing out on opportunities for a triumphant pregnancy. Conversely, transferring mosaic embryos could potentially lead to implantation failure or an increased risk of miscarriage, even though the clinical significance of low-level mosaicism remains a subject of ongoing debate.
| PGT-A Result | Estimated Mosaicism Rate (Based on Recent studies) | Potential Impact |
|---|---|---|
| Euploid (Normal) | 10-30% | May contain undetected mosaicism; potential for false reassurance. |
| Aneuploid (Abnormal) | Variable | Accurate identification of embryos with significant chromosomal abnormalities. |
A study published in the journal Reproductive Biology
