Assisted hatching

The Implantation of the embryo into the endometrium occurs several days after fertilization. Normally, the embryo erodes the zona pellucida that surrounds it, causing it to thin, so that it can hatch, attach to the endometrium and settle in for development (implantation). If the zona pellucida is thicker than normal, hatching is theoretically impaired. Therefore, the embryologist may facilitate embryo hatching after IVF, by opening a hole in the zona pellucida (either by chemical corrosion, or by using a special laser attached to the microscope), before transferring the embryos into the uterine cavity.