Assisted Hatching

There is another critically important component of the embryo that is often overlooked - the zona pellucida (ZP) or the egg shell. The zona pellucida is secreted by the egg and has several important functions:

  1. During fertilization, it serves to prevent the access of more than one sperm to the egg
  2. It keeps the cells of the embryo together during early development, until the embryo reaches the blastocyst stage. At the blastocyst stage, the embryo has enough structural integrity that it no longer needs the protection of the ZP and the embryo "hatches".

In 1989, Cohen and his co-researchers observed a higher implantation rate in patients undergoing IVF who had the ZP of their embryos mechanically opened.

Prospective randomized clinical studies have been performed in order to evaluate the effectiveness of assisted hatching in IVF. Several studies report a significant increase in embryo implantation and clinical pregnancy rates in select groups of patients whose embryos have undergone this procedure.

Who Needs Assisted Hatching?

The following groups may benefit from assisted hatching:

  • Women over 36 years of age
  • Women with elevated FSH levels
  • Couples with previous IVF failures
  • Embryos with an abnormal appearing zona pellucida,
  • Couple using cryopreserved embryos.

How is Assisted Hatching Performed?

There are a number of ways to introduce a hole or a weakness into the ZP:

  1. Laser: A laser is used as an energy source to create an opening in the ZP.  The laser operator precisely controls the laser energy output, pulse duration and gap size. This method has many benefits when compared to the more standard mechanical and acidified tyrodes techniques. The computer assisted laser method is more precise, resulting in a more consistent ZP opening. Laser-assisted hatching takes less time and does not expose the embryos to potentially adverse chemicals, so embryos spend less time out of the optimal culture conditions of the incubator.
  2. Mechanical: Mechanically piercing the ZP with a specifically designed pipette.
  3. Chemical Erosion: Exposing the embryo to an acidified media called acidified tyrodes solution. This acidic solution is microscopically applied to the ZP to induce thinning.

Barbados Fertility Centre has routinely performed assisted hatching since 2002. We offer both the mechanical and the laser methods.