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Sunday, 24 August 2014

Assisted Hatching

Human eggs have a shell all around. This shell is called Zona Pellucida or just Zona in short. The function of the zona is to protect the embryo and to maintain its integrity (by keeping all cells of the embryo together). The function of zona ends when it is time for implantation. An embryo has to hatch out this very shell at the blastocyst stage, otherwise pregnancy will not occur.

Assisted Hatching is a technique which is used to either make a hole in the zona. The thought is to 'assist' an embryo which may either have a thicker zona or lesser ability to make a hole in the zona. 

There are three methods of Assisted hatching: 

  • Mechanical (in which the zona is tangentially pierced with a special needle)
  • Chemical (in which a chemical is delivered to a limited area of the zona to make a hole, the extra chemical is then removed to prevent the chemical from damaging the cells of the embryo)
  • Lasers (where energy from laser is used to make a very controlled breach in the zona)

Assisted hatching is generally applied to Day 3 embryos but can also be applied to Blastocysts to increase implantation rates. 
The current opinion with regard to the use of Assisted Hatching is that this technique can be offered to couples with previous implantation failures, and may improve the pregnancy rates in patients undergoing thawed embryo transfer. It is not clear whether it is beneficial for patients of advanced age. It is not without risks and therefore not recommended for routine use.

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