The normal process of conception requires escape or “hatching” of the early embryo from the zona pellucida shell. Hatching usually occurs around the 5th or 6th day following fertilization and is required for the embryo to attach, or implant, in the uterus. Assisted hatching is a laboratory procedure designed to open the zona pellucida or “shell.” Assisted hatching is accomplished by using a microscope-mounted laser to create a small hole in the outer shell of the embryo.
It is performed for a variety of reasons: