The unfertilised egg is surrounded by a shell called zona pellucida. The zona pellucida ensures that only one sperm cell enters and thus fertilises the egg. After fertilisation of the egg, zona pellucida keeps the cells of the embryo together.
Prior to the implantation, the embryo has to escape from the ZP, a process known as hatching.
During in vitro culture of the human embryo, zona pellucida gets harder, possibly due to the culture conditions. Removing the egg for in vitro fertilisation and micro insemination takes it out of its natural environment. This procedure tends to lead to egg shells that harden faster than seen in vivo.
Especially women older than 37 years of age, have a tendency to produce eggs with a harder zona pellucida than younger women. The same applies for women treated with higher doses of follicle stimulating hormone (FSH).
Laser assisted hatching is one out of several methods to help the fertilised egg to hatch and attach to the uterus.
We recommend laser assisted hatching for patients who have undergone repeated treatments without conceiving, and/or in cases where the woman is over 37 years of age.