It has been speculated that fertility medications and the egg’s normal aging process can cause changes in the zona pellucida (the protective outer membrane that surrounds the embryo), which may interfere with the normal hatching process. Assisted hatching is a procedure in which a hole is made in the zona pellucida to help improve the chances of implantation.
The assisted hatching procedure is performed chemically, with a microscopic needle, or with a laser. During the assisted hatching procedure, a small hole is made in the zona or the zona is thinned using a micromanipulation method. The embryos are then transferred into the uterus. Normally, the embryo must “hatch” through the zona pellucida in order to attach to the lining of the uterus. Assisted hatching helps embryos with thicker outer shells than normal to return to a normal state where they can now hatch.