Before a human embryo attaches to the wall of the uterus (womb), it must hatch (break out) from the outer layer (zona pellicuda). Assisted hatching involves thinning this layer to help embryos hatch, and this increases the chance of a successful pregnancy.
What is assisted hatching?
Assisted hating is an assisted reproductive technique (ART) used during in vitro fertilization (IVF). This procedure allows embryos to hatch out of the outer layer so they can implant into the woman’s uterus. When hatching problems exist, assisted hatching greatly increases the odds of a viable pregnancy.
What is the zona pellicuda?
The zona pellicuda is a protective outer layer that surrounds the embryo. The embryo must break through this layer, much like a baby child breaking out of an eggshell. When the zona pellucida is too thick, or the embryo is too weak, this can affect the hatching process.
Where does assisted hatching occur?
Assisted hatching is done when the embryo is in the laboratory. The doctor makes a tiny hole in the zona pellicuda, or this layer is thinned. The procedure involves use of a laser, acid, or mechanical methods.
How is the assisted hatching procedure done?
On the third day of embryo development, the doctor uses a microlaser, microtool, or weak acid to thin the outer layer around the embryo. When acid is used, the embryo must be washed afterwards. After the hole is made in the outer layer, the woman is given antibiotics to ward off infection.
What are the methods of thinning the zona pellucida?
To create an opening in the zona pellicuda, the embryo can be treated with one of the following techniques:
- Drilling with Tyrode’s solution – This is an acidic solution that contains a proteolytic enzyme used to dissolved the zona pellicuda. After applying the solution, the embryo must be rinsed several times.
- Laser drilling – To create a small hole, a laser is used to thin the outer layer.
- Partial zona dissection – Called PZD, a micro-needle is used to pierce the zona pellicuda.
- Piezo-micromanipulator – This device uses vibrating electric pulses to create a small opening in the outer layer.
- Mechanical expansion – This mechanism stretches the zona pellicuda to assist with hatching.
What are the risks associated with assisted hatching?
There are no more chance of birth defects using assisted hatching than seen with normal conception. Since the outer layer surrounding the embryo is manipulated, there is no injury. However, if more than one embryo is transferred, there is a risk for multiple births.
Who would benefit from assisted hatching?
Assisted hatching has helped thousands of infertile couples globally. Candidates include:
- Any woman age 38 years and older.
- Women with high follicle stimulating hormone (FSH) levels.
- Anyone with poor egg quality.
- Women with poor embryo quality.
- Anyone who has failed to become pregnancy in prior in vitro fertilization cycles.
Can assisted hatching benefit IVF patients?
Many fertility experts recommend using assisted hatching for in vitro fertilization cases where embryos lack adequate energy to complete the process. Assisted hatching can increase the chance of successful implantation. However, no every couple using IVF needs assisted hatching assistance.
What is the success rate associated with assisted hatching?
According to current clinical research, assisted hatching improves the result of an in vitro fertilization treatment, but this varies from couple to couple. The age of the woman is an important factor, with women ages 35 to 39 years having a 50% chance of achieving pregnancy. Advanced age lowers the success rates associated with assisted hatching.