What is Laser Assisted Hatching?

Assisted Hatching (AH) is a micromanipulative technique, used to increase implantation rates by facilitating hatching of the embryos following IVF/ICSI.

In order for an embryo to complete its implantation in the endometrium, it must develop to the blastocyst stage and then hatch, i.e. break through the outer membrane known as Zona Pellucida. The zona is a glycoprotein layer, which completely surrounds the oocyte and the embryo after fertilization. If the zona pellucida is too thick or too rigid, the blastocyst may fail to hatch and will result in implantation failure. It is therefore suggested that if a hole is made in the zona, this could aid the hatching process.

How is AH performed?

There are three methods of AH, the mechanical (Partial Zona Dissection), the chemical (Zona Drilling) and the Laser-assisted. The first two are historical methods and are rarely performed in laboratories; they have instead been replaced by the Laser-assisted hatching method, as it provides precise incision on the early cleavage embryos’ zona pellucida prior to their replacement.

When is AH recommended?

Assisted Hatching is applied in patients with poor prognosis such as:

  • couples with advanced maternal age
  • couples who have encountered repeated failures in previous in vitro fertilization procedures
  • embryos with abnormal zona pellucida thickness

It may also be performed on days 3/4 if embryo biopsy is to be carried out on blastocysts on days 5/6. It enables the trophectoderm to protrude through the drilled hole and thus facilitate the removal of the protruding cells during the biopsy procedure.