The most important step for a doctor performing in vitro fertilization (IVF) is selecting the best possible embryo to implant in the uterus. As success rates for IVF have improved and cryopreservation became widely available, many clinics now implant a single embryo during an IVF cycle to avoid a multiple pregnancy. Hence, the responsibility of selecting the embryo falls to the embryologist.
To determine the quality and viability of an embryo, embryologists typically examine specific features of the embryos using a light microscope. In addition, specialists can use data from preimplantation genetic testing for aneuploidy (PGT-A), a test of whether cells from the embryo at the blastocyst stage have a normal or abnormal number of chromosomes. However, this crucial test carries the risk of false positives (which could lead to discarding a normal embryo) and false negatives (which could lead to transferring an embryo with a chromosomal abnormality).
A team of researchers from Brigham and Women’s Hospital, in collaboration with colleagues at Peking University have evaluated a new way to conduct preimplantation genetic testing and present results showing that this new method may improve the reliability of the test. Their findings are published in Proceedings of the National Academy of Sciences.
“This technique holds the promise of a more precise test than the current method,” said co-corresponding author Catherine Racowsky, Ph.D., director of the IVF laboratory at the Brigham, and professor in the Department of Obstetrics and Gynecology at Harvard Medical School. “It represents a new way to evaluate embryos with less risk of discarding a viable embryo.”
Instead of making a biopsy of an embryo, the new test analyzes DNA leaked from human blastocysts into the culture medium in which they are growing. The technique has several potential advantages. Since it is non-invasive, it does not interfere directly with the embryo and is more accurate: new test reported false positive in 20% of the cases compared with 50% for an old invasive test.
Source: Wall Street Journal