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Embryo Squishiness May Predict IVF Viability

February 26, 2016

Much like choosing a ripe piece of fruit, how ‘squishy’ an embryo is can predict its viability potential for in vitro fertilization (IVF), says a new study published in the prestigious journal Nature Communications.

The technique of gently squeezing embryos was found to be a more accurate and even earlier way for Stanford and Montana State University researchers to select which ones should be used for transfer and implantation.

Consequently, the study shows that this squeezing method could improve the success rates of in vitro fertilization (IVF).

Traditional Embryo Evaluation Methods

During a typical IVF process, embryologists will fertilize eggs in a lab dish, and then wait five or six days for the fertilized eggs to form into blastocysts– hollow balls of cells that have been found to be the optimal stage for an embryo to be implanted in the uterus.

During the pre-implantation blastocyst stage, embryologists will examine each embryo’s viability potential in order to select the one with the highest chance of success. Sometimes, more than one embryo is selected for transfer, which could lead to multiple births (twins, triplets, etc.).

However, “This can increase the risk of neonatal mortality and cause complications for babies and the mothers,” says lead author Livia Yanez, a doctoral student of bioengineering at Stanford University in a statement.

Currently, embryologists evaluate embryo viability using methods such as examining its morphology and rate at which cells have been dividing. In addition, pre-implantation genetic testing (PGS/PGD) can be used on cells plucked from the blastocyst to test for genetic defects.

These current evaluation methods can still be uncertain with up to a 70 percent failure rate.

Study’s Embryo Squish Test

Using a small pipette, researchers applied a small amount of pressure to mice eggs an hour after fertilization and recorded the degree of deformity before incubating them to the blastocyst stage.

The eggs that had provided a certain range of “push back” were more likely to produce healthy-looking, symmetrical embryos. They then transferred these embryos to mother mice for implantation.

Embryo Success Rates

Using mice embryos, those that were classified as viable based on squishiness were 50 percent more likely to result in a live birth than embryos classified as viable using convential techniques, the study showed.

When repeated with fertilized human eggs, the mechanical ‘squeezing’ technique could predict with over 90 percent accuracy which embryos would develop into healthy blastocysts, and could do this within only hours of fertilization instead of days with traditional evaluation techniques.

David Camarillo, an assistant professor of bioengineering at Stanford states, “It is still surprising to think that simply squeezing an embryo the day it was fertilized can tell you if it will survive and ultimately become a baby.”

These are exciting potential results to help improve IVF success rates. More research is needed to see if these results can be replicated by others in academia as well as those practicing in private clinic settings with a diverse range of patients.

Photo Source: Camarillo Labs, Stanford University


Fertility, Health and Wellness, Reproductive Medicine, Research and Development


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