After transfer to the uterus, the embryo must implant in the uterine lining and continue its development. In order to do this it must break out of its “shell”. This shell is called the zona pellucida. Embryos may have a harder than normal shell or they may lack the energy needed to break out and complete the “hatching” process. Embryologists can assist this hatching by make a small hole in the zona pellucida of the embryo on the third or fifth day of the embryo’s growth. This is done through a specially fitted laser microscope. The cells of the embryo can then escape from this hole and implant at an earlier time of development when the uterine lining may be more favorable.
Some embryos grown in the laboratory may have a harder shell than normal or may lack the energy requirements needed to complete the hatching process. The embryologists can help these embryos achieve successful implantation through a technique called assisted hatching. On the third or fifth day of laboratory growth and shortly prior to uterine transfer, a small hole is made in the zona pellucida of the embryo with a specially fitted laser microscope. Through this opening, the cells of the embryo can escape from the shell and implant.
Assisted hatching is thought to be helpful for couples with a poor prognosis whose embryos are thought to lack sufficient energy to complete the hatching process.
According to the American Society for Reproductive Medicine, assisted hatching may be indicated for women with: