For the first 5 to 7 days of development, the embryo is surrounded and protected by an outer shell called the zona pellucida. In normal circumstances, when the embryo reaches the uterus, this zona partially dissolves and the embryo ‘hatches’ out, allowing it to implant in the uterus.
In some patients it is thought that infertility may be caused by a hardening of the zona, which makes it difficult for the embryo to hatch and implant.
Assisted hatching is a laboratory micromanipulation technique carried out before the embryos are replaced in the uterus following an IVF or ICSI cycle that helps the embryo to hatch from the zona.
Who is assisted hatching suitable for?
Assisted hatching is generally recommended in the following circumstances:
- The woman is aged 35 years or older
- The woman has high FSH levels
- Couples who have failed to get pregnant following previous IVF cycles
- Couples where a distinct thickening of the zona is noted by the embryologist.
- Frozen embryo replacements.
what does assisted hatching involve?
Assisted hatching is carried out in the laboratory by experienced embryologists. Using a very high powered microscope, a small slot is made in the zona using a very fine needle. Assisted hatching is carried out before the embryo transfer on those embryos that have been chosen for transfer. Once it is returned to the uterus, the embryo can hatch through this opening and implant naturally.