Assisted hatching

Under normal circumstances the protective layer that surrounds the embryo known as the zona pellucida undergoes gradual thinning due to the expansion of the growing embryo and the increased pressure causes the zona to break and the embryo hatches and then implants in the uterus around day 5 or day 6.

In some specific couples , the embryos have very thick zona which may be the cause of implantation failure. Assisted Hatching is the method using micromanipulation techniques such as mechanical , chemical or laser to create a small hole at the zona which may help the embryo escaping from its shell.

The most commonly used indications for assisted hatching with an in vitro fertilization case are:

• Age factor - Couples having IVF with the female partner's age over 37
• Egg quantity and quality factor - Couples in which the female's day 3 follicle stimulating hormone (FSH) level is elevated
• Embryo quality factor - Couples having IVF with poor quality embryos (excessive fragmentation or slow rates of cell division)
• Zona factor - Couples having IVF with embryos that have a thick outer shell (zona pellucida)
• Previous failures - Couples having IVF that have had one or more previous IVF cycles that failed

Pregnancy rates for in vitro fertilization procedures with assisted hatching have been shown in some published studies to be higher than for IVF without hatching. There is an improvement in implantation and pregnancy rates in our IVF clinic with the use of assisted hatching. This is not seen in all IVF programs.

It is possible to damage embryos with hatching and lower the pregnancy rate in a program. Therefore, it is essential that if assisted hatching is done, it must be expertly performed by properly trained embryologists.

The actual pregnancy and live birth rates seen in an individual IVF center will vary according to the hatching technique used, the overall quality of the laboratory, the skill of the individual performing the hatching, the embryo transfer skills of the physician, and other factors.