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New Study to Identify High-Quality Embryos for IVF

A human oocyte (egg). Source: Texas Fertility Center

A worldwide study that is led by Texas Fertility Center, an Austin, TX, fertility clinic, and includes top fertility clinics in the United States, Spain, Israel, France, Japan and the Netherlands, has the goal of dramatically changing how scientists determine embryo viability for in vitro fertilization (IVF).

Typically during IVF, the embryologists in the lab select the embryos to transfer to the uterus via a method called embryo grading. This is a subjective system based on the appearance of the embryo under the microscope. For example, with a Day 3 embryo, a Grade 1 embryo might have cells of equal size and no fragmentation (when a small portion of the cytoplasm inside the cell breaks off) compared to a Grade 4 embryo with cells of unequal size and moderate to heavy fragmentation. There are different grading systems for Day 5 (blastocyst) embryos.

Embryo grading is an imperfect tool to determine which embryos have the best potential for a healthy pregnancy and birth. The technique has limited ability to determine which embryos are most likely to implant because at least 60 percent of human embryos that may appear normal under a microscope are actually chromosomally abnormal and are likely to not implant or miscarry.

Now the new embryo biomarker study led by Kaylen Silverberg, M.D., a reproductive endocrinologist with Texas Fertility Center in Austin and the principal investigator on the study, could bring about a more precise method of selecting viable embryos for transfer in IVF cycles. The hope is that the study, which began enrollment in July 2011, will benefit couples experiencing infertility and recurrent miscarriage, as well as women of advanced maternal age.

With IVF, the egg is fertilized with the sperm in the laboratory. A high concentration of sperm is placed around each egg in dishes with a type of growth medium. They are left together overnight in an incubator to allow “natural” fertilization to take place. The resulting embryo is then allowed develop and grow for several days in the growth media. Interestingly, embryos secrete chemicals into the media during their brief stay, and many of these biomarkers have been associated with enhanced embryonic viability based on whether they are produced in higher or lower concentrations during embryonic development.

"These biomarkers help fertility doctors and embryologists determine whether an embryo is growing normally or dying,” explains Dr. Silverberg.

Patients in the study will undergo IVF, and at egg retrieval, the granulosa cells and surrounding fluid will be sampled, preserved and shipped to a testing facility. At the embryo transfer, growth media surrounding the embryo will be sampled, preserved and shipped to a testing facility. This two-arm study will investigate the chemicals secreted from the egg and chemicals secreted from the embryo as indicators of health.

“We are optimistic that this new protocol for objectively identifying the most viable embryos will greatly improve a couple’s odds of conceiving a healthy baby,” says Dr. Silverberg. “The outdated, subjective method that relied on visual assessment of embryo health has served us well for many years. We now have new technologies that can hopefully propel us to even higher success rates; it is time for a change."


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