Assisted
hatching is a laboratory technique designed to enhance implantation of
embryos generated through in
vitro fertilization (IVF). Combined with fragment
removal, this technique is thought to promote development of embryos
adversely affected by fragmentation.
Fragmentation is found in some 80% of IVF embryos, and it implies that sometime
during the process of division, pieces of cytoplasm have been lost from the
dividing cells. Although the exact causes of fragmentation are not known, this
phenomenon may be linked to extrinsic factors such as in
vitro culture conditions. The inherent properties of the eggs and sperm that
created the embryo can also contribute to fragmentation. Judging by its
prevalence, some forms of this phenomenon may be a part of normal development,
however, it is clear that significant fragmentation interferes with implantation
and pregnancy and could be a cause of infertility.
Assisted hatching and fragment removal together may restore a compromised
embryo’s development potential to become a fetus (baby). Candidates for this procedure are chosen based
on the female’s age, the presence of elevated follicle stimulating hormone,
degree and pattern of fragmentation found in the embryos, the thickness of the zona
pellucida (the protective outer shell of the egg that remains until
implantation) and/or the number of previously attempted IVF cycles.
Assisted Hatching Procedure
Assisted
hatching is a micromanipulation technique developed to help embryos
"hatch" or escape from the zona pellucida. Hatching is a pre-requisite
to implantation and normally a process carried out by the embryo itself. During assisted
hatching, while the embryo is held on a holding pipette (a fine glass tube),
a micro-needle is loaded with an acidified solution. The solution is quickly and
gently applied to a small area of the zona pellucida until the area is
dissolved, creating a tiny hole and providing the embryo with an artificial
"escape route".
