Assisted Hatching With IVF
What is Assisted Hatching?
Assisted hatching is a fertility technique, used as part of IVF treatments, to facilitate the embryo hatching and implantation process. A fertilized embryo is covered by a shell, called the zona pellucida. To result in a successful pregnancy, the egg must hatch—and break out of the zona pellucida—and attach to the lining of the uterus. During assisted hatching, an embryologist thins or weakens the barrier around a fertilized embryo at a single point. A perforated zona pellucida increases the chances the embryo will hatch and successfully implant.
In a natural pregnancy, when the embryo reaches a stage of development known as the blastocyst stage, the zona begins to thin. The thinning process is spurred on by repeated contracting and expanding of the blastocyst, which alters the elasticity of the zona. Once the zona is sufficiently thinned, it tears allowing the embryo to hatch. Embryos that do not hatch will not be able to implant. Multiple studies have observed that natural hatchings in human blastocysts tend to occur close to the inner cell mass. In assisted hatching, embryologists apply the observed behavior of successful natural hatching to increase the likelihood of implantation for our IVF patients.
What is Assisted Hatching?
Assisted hatching is a fertility technique, used as part of IVF treatments, to facilitate the embryo hatching and implantation process. A fertilized embryo is covered by a shell, called the zona pellucida. To result in a successful pregnancy, the egg must hatch—and break out of the zona pellucida—and attach to the lining of the uterus. During assisted hatching, an embryologist thins or weakens the barrier around a fertilized embryo at a single point. A perforated zona pellucida increases the chances the embryo will hatch and successfully implant.
In a natural pregnancy, when the embryo reaches a stage of development known as the blastocyst stage, the zona begins to thin. The thinning process is spurred on by repeated contracting and expanding of the blastocyst, which alters the elasticity of the zona. Once the zona is sufficiently thinned, it tears allowing the embryo to hatch. Embryos that do not hatch will not be able to implant. Multiple studies have observed that natural hatchings in human blastocysts tend to occur close to the inner cell mass. In assisted hatching, embryologists apply the observed behavior of successful natural hatching to increase the likelihood of implantation for our IVF patients.
Candidates for Assisted Hatching
Several factors can make someone a candidate for assisted hatching with in vitro fertilization. Patients who have experienced previous failed IVF cycles, patients whose embryos have a zona pellucida that is unusually thick, patients whose embryos are not developing as well as expected, patients with elevated FSH levels during follicular phase, or patients older than 35 can all benefit from assisted hatching. Since there are no known downsides, and the potential for increased implantation rates exists, Aspire believes that all IVF patients can benefit from our advanced assisted hatching techniques.
IVF Assisted Hatching Methods
There are three methods for IVF Assisted Hatching:
- Laser Assisted Hatching
- Acid Tyrode's Solution
- Partial Zona Dissection (PZD)
Assisted hatching is performed immediately before embryo transfer. Although the goal of each technique is to weaken or perforate the zona pellucida, the differences in methodology are significant.
Laser assisted hatching is a more modern approach. It utilizes specialized software that aids in positioning, intensity, and focus of the lasers. In this method, the thickness of the zona is measured, allowing our embryologists to minimize the heat delivered to the adjacent inner cell mass. Aspire uses the laser assisted hatching method because it is the safest for the embryos, and our embryologists can set up and perform laser assisted hatching with more speed and precision than other methods.
Acid Tyrode’s solution uses a tiny microneedle to expose a small amount of acid onto the zona through direct contact. A specialized holding pipette is used to restrict the movement of the embryo. As the acid melts away the zona, it is advanced into the embryo, creating a small hole. After the hole is created, the embryo is washed, placed back in culture medium, and reincubated until the time of embryo transfer. Acid Tyrode’s solution is traditionally the most common method of performing assisted hatching, but clinics are increasingly turning away from this method because of the potential to introduce partially dissolved zona and acid into the developing embryo.
Partial zona dissection (PZD) is a mechanical method that creates a cross-hatched slit in the zona. To create the penetrations, the embryo is held in place with a holding pipette and a microneedle is used to pierce the zona. Once pierced, the embryo is released from the holding pipette and repositioned so that the zona is between the microneedle and the holding pipette. Gentle pressure is applied, causing the microneedle to make a slit in the zona. The embryo is then repositioned and the procedure is performed again, creating a cross-hatched opening in the zona.
What is Aspire’s Assisted Hatching Process?
Here are the steps Aspire uses for the laser assisted egg hatching process:
- There are frequently several steps along the journey from egg retrieval to embryo transfer. The majority of IVF our cases are frozen embryo transfers, and most of our patients elect to have PGS performed. All of this happens before assisted hatching.
- Immediately prior to transfer, the embryo is moved to our micromanipulation station.
- Aspire uses an automated witnessing tool, called RI Witness, to verify that all laboratory procedures are performed on your embryo, virtually eliminating the risk of mixing up your embryo with another patient. Learn more about RI Witness.
- Your embryo is then placed on the inverted microscope of the micromanipulation station, where our experienced embryologists determine the best location to perform laser assisted hatching.
- Using these measurements, the location, focus, and intensity of the laser to adjusted to ensure minimal heat exposure of nearby cells.
- The laser creates perforations in the zona by vaporizing it. Typically, two or three laser pulses are delivered to create the gap.
- Once laser assisted hatching is complete, the embryo is returned to culture medium and placed in the incubator to await transfer.
Success Rates for IVF with Assisted Hatching
Clinical studies have shown that assisted hatching increases the chance of implantation of transferred embryos. While there has not yet been enough research performed to concretely support laser assisted hatching over other methods, Aspire believes it to be the best option for our patients.
