Assisted Hatching

The normal process of conception requires escape or “hatching” of the early embryo from the zona pellucida shell.  Hatching usually occurs around the 5th or 6th day following fertilization and is required for the embryo to attach, or implant, in the uterus.  Assisted hatching is a laboratory procedure designed to open the zona pellucida or “shell.” Assisted hatching is accomplished by using a microscope-mounted laser to create a small hole in the outer shell of the embryo.

It is performed for a variety of reasons:

  1. For IVF cycles involving preimplantation genetic testing (PGT), assisted hatching allows embryologists to gain access to cells for biopsy. Assisted hatching is performed in all PGT cases.
  2. For any cycle where blastocyst-stage embryos are cryopreserved, assisted hatching may help the embryo hatch out of the zona pellucida shell following thaw. Some evidence suggests that freezing and thawing embryos results in some “hardening” of this shell.  At RMSCVA, assisted hatching is performed on all blastocysts at the time they are cryopreserved.
  3. For fresh embryo transfer on day 3, some studies suggest that IVF pregnancy rates are improved if assisted hatching is performed, particularly in older women. Your physician may recommend assisted hatching for fresh embryo transfer in select circumstances that include advanced maternal age or previous IVF failure.

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