In Vitro Fertilization (IVF) is a widely recognized fertility treatment that assists many individuals and couples in their journey to parenthood. Some patients may benefit from supplementary techniques designed to enhance the chances of a successful pregnancy. One such technique is assisted hatching (AH), a laboratory procedure performed on an embryo to potentially aid its implantation into the uterine lining. This method focuses on a natural biological process fundamental for early embryo development and attachment.
Understanding Embryo Hatching
An embryo must emerge from its protective outer layer, the zona pellucida. This transparent shell surrounds the egg and early embryo, safeguarding it during development and travel through the fallopian tube. Once the embryo reaches the uterus, typically around five to six days after fertilization, it needs to “hatch” from the zona pellucida. This step allows the embryo to implant into the uterine lining. Successful implantation is necessary for continued embryonic development and pregnancy.
The Assisted Hatching Procedure
Assisted hatching is a micromanipulation technique performed in the embryology laboratory to create a small opening or thinning in the zona pellucida.
Laser Hatching
One common approach is laser hatching, where a precise, non-contact laser beam ablates a tiny section of the zona. This method is controlled, efficient, and minimizes direct handling.
Chemical Hatching
Another technique, chemical hatching, involves applying an acidic solution, such as Tyrode’s acid, to dissolve a small area of the zona pellucida. This process requires careful monitoring for localized thinning.
Mechanical Hatching
A third method, mechanical hatching, uses a fine glass needle to manually create a small hole or thin the zona. A skilled embryologist manipulates the embryo under a microscope.
Regardless of the method, assisted hatching is typically performed on day three of embryo development (when the embryo consists of approximately six to eight cells) or on day five, just before embryo transfer. The goal is to facilitate the embryo’s ability to hatch and implant.
When Assisted Hatching is Considered
Fertility specialists consider assisted hatching for specific patient profiles and embryo characteristics:
Advanced maternal age, generally defined as women over 37 or 38 years old, as their embryos may have a zona pellucida that is thicker or harder than average.
Embryos that exhibit a visibly thick or abnormal zona pellucida, or those that show poor expansion in culture dishes.
Embryos that did not successfully hatch in previous IVF cycles, despite appearing to be of good quality.
Patients who have experienced multiple failed IVF cycles where good quality embryos were transferred but failed to implant.
Additionally, certain indicators of reduced ovarian reserve, such as elevated Follicle-Stimulating Hormone (FSH) levels, can sometimes correlate with zona abnormalities, prompting consideration for this technique.
Potential Considerations and Outcomes
Assisted hatching is a specialized procedure that may offer benefits for certain IVF patients. Studies suggest AH can improve implantation rates, particularly for patients with a thicker or more resistant zona pellucida. However, it is not universally applied, as its effectiveness varies depending on underlying factors.
While modern techniques, especially laser hatching, are precise, there is a minimal risk of damaging the embryo. This risk is managed by experienced embryologists using advanced microscopic equipment.
Some research indicates a slight increase in multiple pregnancies following assisted hatching, due to enhanced implantation potential. Clinics manage this by carefully selecting the number of embryos transferred. The decision to incorporate assisted hatching into an IVF cycle is individualized, made in consultation with fertility experts. It involves balancing the potential for improved implantation with any considerations.