What is it?
Both the unfertilized egg and embryo are surrounded by a protected shell called the zona pellucida. In order for the embryo to implant to the wall of the uterus -it must hatch out of this zona shell. In women over the age of 38 the zona hardens which makes it more difficult for the embryo to complete the hatching process. This would then decrease the likelihood of implantation and pregnancy in these patients.
Assisted hatching is the IVF technique whereby a mild acid solution is applied to a small portion of the shell to weaken the shell so that hatching can occur more easily. This hatching process is a laboratory technique performed on the embryos and is done shortly before the embryos are transferred back into the uterus.
Assisted hatching is recommended for women over the age of 38, as well as patients with unexplained infertility. In patients where the zona appears to be thick assisted hatching is also a helpful procedure.
Embryos and/or patients that meet the criteria below are candidates for selective assisted hatching. Good quality embryos demonstrating a normal rate of development will not receive the assisted hatching treatment as it may reduce a good quality embryo’s ability to implant into the uterus. Assisted hatching is performed on cleavage-stage embryos that are transferred to the uterus three days after egg retrieval. The UIHC IVF laboratory does not perform assisted hatching on blastocysts (embryo transfer five days after egg retrieval).
Assisted hatching has been shown to improve embryonic implantation rates in women who:
- have failed to achieve embryonic implantation after several IVF cycles
- have poor quality embryos or embryos that are behind in development
A soft shell called the zona pellucida surrounds the embryo. The zona pellucida protects the embryo during early development. As the embryo develops, the zona pellucida thins. The embryo must hatch out of the zona pellucida prior to implantation into the uterine wall. It has been suggested that some unsuccessful cycles of assisted reproduction are due to the inability of the embryo to hatch out of the zona pellucida or delayed hatching which prevents the embryo from subsequently implanting into the uterine wall during the implantation “window of opportunity”.
Embryos that may otherwise remain trapped within the zona pellucida may be rescued by a technique called assisted hatching. Assisted hatching at the UIHC IVF laboratory is accomplished by dissolving a small hole in the zona pellucida just prior to transcervical embryo transfer. It is through this small hole that the embryo may eventually hatch out of a zona pellucida.
Assisted hatching is recommended for infertile couples if:
- the woman is 38 years or older
- the woman has a high follicle stimulating hormone level
- they have failed to achieve a pregnancy in a prior IVF cycle, or
- the embryos are fertilized using intracytoplasmic sperm injection (ICSI).
- Frozen-thawed embryos
AH increases the success rate of IVF for certain women.
The AH procedure may increase the rate of monozygotic twins. Rare side effects from the accompanying steroid treatment can include: elevation in blood pressure, salt or water retention, a higher susceptibility to infection, mood swings, insomnia, osteoporosis, nausea, and allergic reactions. The antibiotic used (usually doxycycline) may increase skin sensitivity to sunlight and may increase your risk for a vaginal yeast infection.
On the day of IVF egg retrieval, the patient should begin four days of treatment with steroids (to suppress the mother's immune system) and antibiotics (to remove any infectious agents in the uterus). On the third day after egg retrieval, the laboratory staff will use a microscopic glass pipet to place an extremely small amount of fluid on the outer coating of the embryo. This fluid dissolves part of the outer coating. The embryos are then transferred into the uterus as in a standard IVF cycle.