Laser Assisted Hatching (Laser-AHA)

Overview

When you conceive spontaneously, the embryo moves through the fallopian tube, allowing the shell to shrink and making implantation simpler. Embryos developed in a laboratory have a thicker shell than normal and may require further assistance to break free.

These outer shells may thicken as women age, making it more difficult for the embryo to break through. Many specialists feel that making a hole in the shell increases the embryo's chances of hatching and implanting into the uterine lining.

The zona pellucida is a delicate outer shell' of a human embryo (or zona for short). When an embryo is five or six days old and at the blastocyst stage, it must escape or hatch out of the zona. Once the embryo has hatched from the zona, it can implant into the uterine lining. A pregnancy cannot develop if the embryo does not hatch.

 

What is Assisted Hatching?

Fertilization occurs in the lab during IVF therapy. However, as every couple who has had IVF therapy knows, having a fertilized embryo does not ensure pregnancy. For pregnancy to occur, the transplanted embryo must implant itself into the endometrium and "stick."

Assisted hatching is a form of assisted reproduction that is occasionally used in conjunction with traditional IVF therapy. The premise behind aided hatching is that it may aid in embryo implantation. This technique is usually indicated when there has been repeated unexplained IVF failure or when the patient has a poor prognosis.

 

How Embryos Hatch?

Understanding the natural hatching of an embryo is helpful in understanding assisted hatching. You start with an oocyte or egg before you obtain an embryo. The oocyte is surrounded by a protein shell known as the zona pellucida. The zona pellucida has several roles in embryo development, and these responsibilities shift as the embryo matures.

The zona pellucida combines with sperm cells before the egg develops into an embryo. This union marks the beginning of the fertilization process. The zona pellucida hardens when a single sperm cell enters the shell and fertilizes the egg. This hardening precludes further sperm cell entry into the now-fertilized embryo.

The tough shell also prevents the embryo from implanting early in the fallopian tubes, resulting in an ectopic pregnancy. It also helps to keep the blastocyst cells together.

The zona pellucida swells and begins to weaken and degrade as the zygote travels down the fallopian tube and develops into the blastocyst stage. The zona pellucida splits open about day four of development, allowing the blastocyst/embryo to emerge, leaving behind the thin protein shell. The embryo hatching process is represented by this stage.

The blastocyst attaches itself into the endometrium within a few days after hatching. A blastocyst cannot embed itself into the uterine wall unless it hatches, and so a pregnancy cannot occur.

 

Methods Used

You might think that assisting hatching always entails creating a little "break" or rip in the zone pellucida. But that is not the case. There are several ways available, and each embryo lab takes a distinct approach.

Every method has advantages and disadvantages, and the technician's ability is important. Make an effort to obtain as much information as possible in order to make an educated conclusion.

• Mechanical hatching: The embryologist uses a pipette to hold the embryo firmly while using a micro-needle to penetrate through the zona pellucida, go just beneath the shell for a little, and then come out the other end. (Consider drawing a very tiny line only along the embryo.) The region between the two punctures is then pressed gently until a tiny rip forms. This approach makes it difficult to manage the size of the aperture.
• Mechanical expansion of the shell: The zone pellucida is not broken open with this approach. Instead, hydrostatic pressure is applied directly beneath the shell to induce it to expand. This approach was inspired by the natural expansion of the outer shell during the hatching process.
• Chemical hatching: This method employs a substance known as Tyrode's solution. The shell is penetrated by applying small quantities of acid to the zona pellucida. The embryo is then rapidly cleansed to minimize excessive acid exposure.
• Drilling: Drilling uses vibratory motions to generate a conical aperture. This approach makes use of Piezo technology.
• Laser-assisted hatching: Another option is to use a specialized laser to break through the zona pellucida. Laser-assisted hatching gives you far more control over the size of the hole than mechanical hatching using a needle.

 

What is Laser-assisted hatching (LAH)?

Laser-assisted hatching (LAH) is a laboratory process that uses an ultramodern laser to gently thin the outer shell (zona pellucida) of a fertilized egg. Thinning the embryo's outer shell increases its odds of correctly "hatching" and may boost the chances of successful implantation and pregnancy.

Assisted hatching is intended to overcome any obstacles that are impeding hatching. It is also believed that it may increase the chances of successful implantation and, eventually, pregnancy.

Laser-assisted hatching may be the safest and most successful way. However, not every embryology lab is equipped with this equipment. Chemical hatching is increasingly popular. With any of these approaches, the embryologist's expertise and experience level can make a significant impact.

 

What’s the evidence for assisted hatching?

The National Institute for Clinical Excellence (NICE) is the national authority that provides treatment recommendations to clinicians. Assisted hatching is not suggested since it has not been proved to increase pregnancy rates

According to NICE, more study is needed to determine if assisted hatching effects birth rates and to investigate the repercussions for children born as a result of this treatment.

Some clinics feel that assisted hatching can increase birth rates in certain patient subgroups. However, no high-quality data exists to support the use of aided hatching in any patient. The evidence foundation for assisted hatching was examined at the October 2019 Scientific and Clinical Advances Advisory Committee (SCAAC) meeting.

 

Who might benefit from this treatment?

Although laser aided hatching can improve your embryos' ability to implant into your uterine lining, it may not be appropriate for every IVF operation. Before recommending laser aided hatching, several variables should be considered, including:

• Advanced maternal age (over 35)
• Elevated levels of follicle stimulating hormone (FSH)
• Previous IVF procedures where embryos failed to implant (but were otherwise in good health)
• Poor embryo quality
• Endometriosis, a condition in which cells from the uterine lining appear outside of the uterus

We will perform a comprehensive investigation to evaluate whether assisted hatching is the best option for your requirements. Unfortunately, most studies on assisted hatching have only reported clinical pregnancy rates rather than live birth rates. Those studies that looked at live birth rates found no benefit. As a result, more research is required.

Another study discovered that when "excellent grade" embryos were aided hatching, conception rates decreased. When assisted hatching was performed on fair- to poor-quality embryos, the outcomes differed depending on age group. These findings suggest that aided hatching will not only not help individuals with a decent prognosis, but may also impair their chances of success.

 

Who does this Technique Works?

This modern IVF approach is a blessing and a fresh hope for couples who have failed to achieve favorable outcomes despite several IVF treatments. This aided hatching procedure has been shown to increase the odds of conception. Assisted hatching is a laboratory process that is frequently performed in conjunction with IVF therapy. The goal of this stage is to help the embryo hatching process and boost the chances of implantation.

The IVF procedure entails mixing eggs and sperm in a laboratory environment and monitoring the embryos for 3 or 6 days as they develop. The best embryo is then implanted into the woman's uterus. The Zona Pellucida is a protective shell formed by cells around the embryo. The embryo spontaneously breaks out from this shell, and pregnancy is only possible if the embryo hatches and implants. In rare cases, this coating becomes excessively thick or rigid as a result of the freezing and thawing process, making hatching more difficult. This is when the aided hatching approach comes in handy.

A tiny hole or crack is produced in the embryo's outer shell to facilitate hatching just before it is implanted into the woman's body. This is done in the hopes that the embryo will grow and embed itself into the uterine wall. A laser instrument is used in laser-assisted hatching to create a highly accurate opening in the Zona Pellucida. This approach allows for precise control over the size of the hole in the shell. Under a microscope, the embryologist sends a quick and powerful laser beam to induce a break in the shell. The embryo is subsequently returned to the uterus to attach to the lining and continue developing.

During an IVF or Intracytoplasmic Sperm Injection (ICSI) cycle, laser assisted hatching is typically performed three days following fertilization, when the embryo has begun to divide. The laser disintegrates the embryo shell by releasing energy. This laser aided approach is incredibly successful at enhancing the success rate of IVF and is completed in a matter of seconds. It is also completely safe for the embryo. The laser hatching approach has been demonstrated to be considerably superior to alternative chemical or manual procedures.

According to fertility specialists, Laser Assisted Hatching can boost IVF procedures by at least 50%. You can consult with your doctor to determine whether assisted hatching is right for you. The parameters that can establish appropriateness include whether the patient is beyond the age of 35 and has had minimal success in naturally conceiving. Couples who have had many IVF failures or women who can generate a high amount of Follicle Stimulating Hormone (FSH) early in their cycle are suitable candidates for the Laser Assisted Hatching procedure. The embryologist can also see if the embryos have a very hard or thick Zona Pellucida through which the laser beam can pass.

 

Laser-Assisted Hatching Complications

Any alteration or meddling with an embryo carries some risk. One danger of assisted hatching is that the embryo will be fatally harmed. This injury might occur before or after embryo transfer. Pregnancy would not occur in either instance. Another danger of aided hatching is that the embryo's natural hatching process is disrupted, and the embryo fails to fully hatch from the zona pellucida.

Monozygotic twins are identical twins born from a single egg and sperm. Twinning is already raised after traditional IVF therapy, and research suggests that aided hatching may increase that risk even further. While all multiple pregnancies are dangerous, monozygotic twin pregnancies are substantially more dangerous for the mother and kids. Twinning is still rare, happening fewer than 1% of the time.

You might question if assisted hatching raises the chance of birth abnormalities. A major retrospective research of over 65,000 assisted reproduction deliveries discovered that aided hatching was "marginally related" with a higher risk of congenital abnormalities, but that the increased risk might have been attributable to other causes.

 

Conclusion 

After embryo transfer, assisted hatching is utilized to help the embryo hatch from its protective outer shell, the zona pellucida, and encourage implantation in the uterine wall. Laser-aided hatching involves less embryo handling than the other assisted hatching procedures. Furthermore, laser-assisted hatching is faster than other procedures, so the embryo spends less time outside the incubator.