Embryo 'squishing' could improve IVF success rates

Scientists found embryos with a certain range of "squishiness" were 50 percent more likely to result in a live birth than those chosen using conventional methods.
By Stephen Feller  |  Feb. 25, 2016 at 12:40 PM
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STANFORD, Calif., Feb. 25 (UPI) -- A new study suggests the most viable embryos for in vitro fertilization could be selected using a test similar to judging the ripeness of fruit -- giving it a little squeeze to see if it's squishy.

Scientists at Stanford found testing the "squishiness" of an embryo helped predict those most likely to lead to a successful birth during experiments with mice.

During IVF, doctors often implant several of the embryos they feel have the best chance to develop into a successful pregnancy based on their cell division rates. In some cases, plucking a cell from an embryo allows for genetic testing to indicate likelihood for development, however this can stress or damage the embryo and defeat the purpose of testing.

Overall, IVF carries a 70 percent failure rate, which is why doctors are so apt to implant multiple embryos and increase the chance for implantation and pregnancy, though this can often lead to complications for either the fetus or the mother, including neonatal death.

IVF could be more successful, the scientists say, with a more reliable method for testing viability.

"From a clinical perspective, once confirmed, the benefit is immense in that it could give us a proxy of viability of the embryo in the blink of an eye, and from that information we can manipulate the patient's cycle in order to improve success," Barry Behr, a professor of obstetrics and gynecology at Stanford University, as well as director of the IVF lab there, said in a press release.

Based on Behr's observation that some embryos are "squishier than others," scientists set out to find out why, and whether it was useful for judging the potential of an embryo to develop.

For the study, published in Nature Communications, researchers applied a small amount of pressure to mouse eggs an hour after they were fertilized, recording how much the eggs deformed. They were then placed in a nurturing liquid and re-examined at the blastocyst stage.

The scientists used this information to create a computer model that, based only on squishiness, could predict whether a fertilized egg would grow properly with 90 percent accuracy. Embryos selected for implantation based on this judgement were seen to be 50 percent more likely to result in a live birth when compared to conventional methods of evaluating an embryo's viability.

"Although cancer and other diseases involve stiff tumors or tissues, our colleagues have been surprised that we can gain so much information from this simple little mechanical test," said David Camarillo, an assistant professor of bioengineering at Stanford University. "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."

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