IVF: Assisted Hatching
Have you ever heard of the fertility term “assisted hatching”? During in vitro fertilization (IVF), a technique called assisted hatching may be performed to help an embryo implant in a woman's womb.
Assisted hatching is considered controversial. In fact, fertility experts are currently debating whether the benefits of assisted hatching outweigh the risks. Read on for more details about this useful, but occasionally detrimental, practice.
What is assisted hatching?
Let's start at the beginning. The first step of pregnancy occurs when sperm fertilize an egg. In cases of natural conception, fertilization takes place in the fallopian tube when you have intercourse around the time of ovulation.
The fertilized egg, now called the embryo, then travels from the fallopian tube into your uterus for implantation. Implantation takes place about a week after fertilization.
If you use IVF to conceive, fertilization takes place outside of your body. After several days, your doctor transfers the embryo into your uterus, where it will hopefully implant and grow. With both natural conception and IVF, the embryo must hatch before it can implant in the womb. To successfully hatch, the embryo must spontaneously rupture through its outer layer, called the zona pellucida.
The assisted hatching procedure
In 1990, the medical procedure called assisted hatching was used to assist the implantation process during IVF. The technique is performed three days post-fertilization, after the embryo has had a few days to develop.
During assisted hatching, the zona pellucida, which coats the embryo, is thinned or ruptured. Sometimes, the outer layer of the zona pellucida is dissolved with an acidic mixture. Alternately, a laser or fine needle may be used to break open the outer layer of the zona pellucida.
Assisted hatching is done with a micromanipulation technique requiring the use of microscopic tools, robotic assistance, and a microscope to view the minuscule embryo. If you use IVF with assisted hatching, the embryo will be transferred into your uterus a day after hatching. To reduce the risk of complications, steroids and antibiotics may be administered, which can sometimes cause side effects.
Who needs assisted hatching?
As we mentioned, hatching is a requirement for all successful pregnancies and births. However, some embryos do not hatch on their own. This is when assisted hatching can be useful.
According to the American Society for Reproductive Medicine (ASRM), assisted hatching is most beneficial for women who have had at least two unsuccessful IVF treatments, as well as women over the age of 38. If a couple's embryos are determined to be of questionable condition, like having a thick outer wall, assisted hatching may also be recommended to boost pregnancy success.
Assisted hatching does not increase live birth rates
Multiple studies have reviewed the success rates of assisted hatching with assorted results. Keep in mind that each fertility clinic has different success and failure rates, due to different standards and procedures. For instance, one factor predicting assisted hatching success is the experience level of the embryologist.
Other factors predicting assisted hatching success are patient characteristics. Those that benefit most from assisted hatching include women over 38 and women who have attempted IVF several times without success. However, even in these groups, live birth rates were not improved in women that used assisted hatching. Therefore, the ASRM does not promote the routine use of assisted hatching during IVF.
Why the controversy?
At a quick glance, assisted hatching appears to be beneficial. Still, complications can and do occur. For instance, some embryos and embryonic cells become damaged or destroyed during the micromanipulation technique. This can lead to IVF failure.
While some research studies have shown that assisted hatching has increased pregnancy and implantation rates for patients, the procedure does not appear to boost live-birth success rates after IVF. Therefore, fertility specialists may consider the ASRM recommendations and not use assisted hatching routinely during IVF.Sources
- Attain Fertility: The role of Assisted Hatching in IVF
- The Practice Committee of the Society for Assisted Reproductive Technology and the Practice Committee of the American Society for Reproductive Medicine The role of assisted hatching in in vitro fertilization: A review of the literature. A Committee Opinion. Fertility and Sterility. Vol. 90, Suppl. 3, November 2008.
- RESOLVE: Micromanipulation Techniques.
- Society for Assisted Reproductive Technology: Micromanipulation