In order for the developed embryo to implant in the uterine wall it must break free of its shell, which is called the zona pellucida.
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 the embryo development and just before the embryo 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 when the uterine lining may be more favorable.
Women who are most likely to benefit from assisted hatching are those:
Age above 38 yrs and above
Repeated failed IVF/ICSI cycles
Embryos with abnormal appearing zonae