During the initial stages of embryonic development, the embryos are contained in a layer of proteins, know as the zona pellucida. The zona pellucida is designed to protect the embryo until it reaches the blastocyst stage of development. In order for an embryo to successfully implant into the uterine lining, the embryo needs to hatch out of this zona pellucida and attach to the walls of the uterine cavity. However, sometimes the embryos may have a difficult time hatching out of their protective layer. This event can occur if the zona pellucida is too thick or if the embryos do not have enough energy to break through this layer. Thus, the procedure called assisted hatching may be needed to help embryos to establish a pregnancy.
The procedure of assisted hatching is another technique of assisted reproduction done during an IVF cycle. Assisted hatching consists of making a small hole in the shell (zona pellucida) of a developing embryo by means of a chemical or laser instrument. Therefore, the hole will help the embryo to hatch out of this protective layer and implant more readily into the uterus.
The procedure of assisted hatching is recommended for women who have failed to become pregnant in previous IVF cycles, poor embryo development, age of 38 and older or have thickened embryo shells, as in the case of eggs coming from patients with polycystic ovarian disease. Assisted hatching is most often performed on embryos transferred on day three after retrieval. Scientific studies have shown that the assisted hatching process improves both implantation and pregnancy rates in many infertile couples.