Assisted hatching is the use of a micromanipulation technique to help an embryo break through the protective shell of the egg (the zona pellucida) and successfully attach to the wall of the uterus. In some women, the zona pellucida of the egg is too hard or tough for the embryo to emerge from the shell. Micromanipulation (using chemical or laser-assisted methods) is used to thin or perforate the zona pellucida