Assisted hatching (AH) is a technique used to, potentially, improve implantation rates. Once an egg has been fertilized (by either conventional IVF or ICSI), the embryo is then assessed to determine it’s quality. Part of this assessment is measurement of the shell thickness (zonapellucida) around the embryo. If the zonapellucida is thicker than normal, this is an indication for assisted hatching.
Assisted hatching is usually done on the 3rd day (8-cell embryo) or the 4th day (morula stage). At the Markham Fertility Centre, we use a small amount of acid to create a small defect (hole) in the zona, itself. In theory, by having this small hole in the shell of the embryo, once the embryo reaches the blastocyst stage, it can “break out” of it’s shell easier to allow for better implantation rates. Many embryos have a normal or thin zonapellucida that is extremely tough or hard to hatch. One cannot determine how hard the zona is until you actually do the assisted hatching procedure itself.
Indications for assisted hatching include:
•Thick zonapellucide measured via IVF
•An elevated FSH level
•Age >38 years of age
•Previously failed IVF embryo transfers without assisted hatching
Occasionally, embryo quality can be improved by removing fragmented debris through the hole created by the assisted hatching procedure. At the Markham Fertility Centre, we still prefer to do a blastocyst transfer for your 1st IVF/ICSI procedure. If a pregnancy is not achieved after your 1st attempt, and it is determined that you have a good blastocyst rate, it is reasonable to tray a day 3 or 4 transfer associated with assisted hatching for a following IVF cycle. We have had very good success rates when assisted hatching is used in conjunction with IVIg therapy.