Laser assisted hatching


Infertility is a major issue and can be caused due to many health and hormonal problems. While this can be a very depressing issue for some couples, modern medicine has helped overcome this problem with the help of alternate options such as In Vitro Fertilization (IVF). With the help of this method, fertilization of the egg is done outside the womb and is later implanted in the uterus wall so that the couple can fully enjoy the period of pregnancy in their lives.

How does a normal fertilization take place?

The Zona Pellucida is a layer of glycoprotein that surrounds the unfertilized egg of a woman. It is an important part of the egg and plays a key role during its fertilization. When sexual intercourse takes place, there are millions of sperms swimming through to get to the egg for fertilization, but only one gets through. While the strongest and the healthiest among the sperms reach the egg to make first contact, the Zona Pellucida is the membrane that prevents the other sperms from entering the egg and hardens itself after the sperm has successfully made first contact with the egg. Although it is an integral part of the egg, it can cause infertility in some women as it can be unnaturally hardened in nature, making the sperm unable to reach the egg for fertilization. This can happen due to various reasons and is mostly common if one opts for an In Vitro Fertilization (IVF). When this case of a hardened shell arises, Assisted Hatching is opted for a more successful pregnancy.

What is Assisted Hatching?

When an embryo is fertilized during a normal IVF treatment, it does not necessarily guarantee pregnancy because sometimes a fertilized egg doesn’t ‘stick’ to the uterine wall as intended. This happens when an egg doesn’t hatch naturally because of a hardened Zona Pellucida due to the clinical involvement on the embryo. Assisted hatching can help overcome this problem by softening the hardened Zona Pellucida and help increase the chances for a successful pregnancy. The different methods of assisted hatching are –

  • Mechanical hatching – In this method of assisted hatching, a tiny needle is used to penetrate the Zona Pellucida just below the shell and then exited through the other side. A small tear is made by gently rubbing the area between the two punctures. The only downside to this method is that the size of the opening is difficult to control and depends on the embryologist’s expertise.
  • Mechanical expansion of the shell – This method is a little different than the other methods. While other methods’ primary concern is opening the Zona Pellucida, mechanical expansion method uses hydrostatic pressure and introduces it just under the shell, leading it to expand instead of opening it.
  • Chemical hatching – Also known as Tyrode’s acid, small amounts of this acid are applied to the Zona Pellucida and to avoid unnecessary acid exposure, the embryo is quickly cleaned. This method has a higher risk of the embryo being destroyed due to the chemicals introduced to the embryo.
  • Drilling – A conical opening is made with the help of vibratory movements.
  • Laser-assisted hatching – This method uses a specialized laser to breach the Zona Pellucida. It takes only a few milliseconds and has the advantage of controlling the size of the hole.

Laser assisted hatching is the most reliable and safest method out of all these methods. It is also easier and quicker to do and the success rates of pregnancy using this method are relatively higher than the other methods.

What is Laser Assisted Hatching?  

Laser Assisted Hatching (LAH) is lab technique that is designed to improve the efficiency of procedures such as IVF & ICSI

A shell called zona pellucida surrounds the unfertilized egg. The zona has an important role in fertilization as it allows only one sperm to penetrate the zona and enter the egg to achieve fertilization. After fertilization, at the cleavage stage of the embryo, the zona pellucida hardens. This is normal and serves to keep the cells in the egg together. To embed into the endometrium lining of the uterine cavity, the cells have to ‘hatch’ out of the zona.

When sperm and eggs are cultured in IVF laboratory, the zona pellucida hardens at much faster rate than in a natural cycle, making it more difficult for the embryo to implant. If this process is not completed properly, implantation failure occurs and a pregnancy cannot be achieved. Assisted hatching is the process of creating a hole in zona, to aid the embryo in the hatching process. A small infra-red laser beam is projected on the zona pellucida of the embryo and the zona is then vaporized or dissolved, creating a 10 to 20 micron hole. Laser Assisted hatching is done just before the Embryo Transfer and improves implantation and improves pregnancy rates.

Why is it done?

It is primarily done to increase the IVF success rates. Women who can benefit from Laser Assisted Hatching are those –

  • Who are above the age of 35 and may have a hardened Zona Pellucida
  • Who have a high Follicle Stimulating Hormone (FSH) levels
  • Who have had previous unsuccessful IVF and ICSI cycles
  • Who have an unnaturally hardened Zona Pellucida
  • Who have frozen embryo transfer

It is considered safe and the sure-fire way to boost up the chances of achieving success.  

How is it done?

LAH is relatively faster, quicker and easier than the other methods of assisted hatching. It is done during an IVF or an ICSI cycle while the embryo is still in laboratory. The outer shell of the embryo is breached and slightly opened by firing a few laser pulses. The Zona Pellucida is thinned down to around 10 microns using laser beams to help and ensure that fertilization takes place. This is done right before the Embryo Transfer and takes very less time than the other methods. The laser is non-contact which means that the embryo does not come in direct contact with the laser which could potentially destroy the embryo. This process takes only a few milliseconds and is done with extreme care and precision.

What are the benefits of Laser Assisted Hatching?

While there are other methods of assisted hatching such as mechanical hatching and chemical hatching, laser assisted hatching is considered the best as it has a higher success rate than the other two. The many benefits of laser assisted hatching are –

  • Safe – LAH is safer because it reduces the various risks that arise out of the other methods. It reduces the risks of the embryo being chemically and manually handled thus decreasing the chances of the embryos being destroyed.
  • Quick – The whole procedure takes only a few seconds and reduces the time the embryo is exposed before it is transferred.
  • Automated – Laser assisted hatching is automated and is done with precision and care. It also removes the need for manually handling an embryo.
  • Success rates – Compared to the other methods of assisted hatching, laser assisted hatching has a fairly higher success rate.

What are the risks associated with it?

It comes with many advantages but there are some risks associated with it as well. The most common risks that come with it are –

  • Destroying of the embryo – While laser assisted hatching is done very carefully through non-contact, it can sometimes come in contact with the embryo and destroy it. This leads to an unsuccessful pregnancy. However, this risk can be prevented if the method is done by extremely trained and experienced doctors.
  • Twinning – Sometimes due to a weak Zona Pellucida, it can result in twinning especially monozygotic twinning. Monozygotic twinning is when identical twins are born from one egg and one sperm. This creates a risk for both the mother and the babies. However, this risk is still lesser than one percent of the cases.

Frequently Asked Questions (FAQs)

Why would one need an Assisted Hatching?

Assisted Hatching may be needed to increase the chances of a successful pregnancy. Though it is not mandatory during a normal IVF or an ICSI cycle, it surely increases the success rates.

What are the methods of Assisted Hatching?

Different methods of assisted hatching are mechanical method, mechanical expansion of the shell, chemical method, drilling and laser assisted hatching.

Why choose Laser Assisted Hatching (LAH)?

Out of the common methods of assisted hatching such as mechanical method and chemical method, laser assisted hatching is the safest and the quickest method.

How is it better than the other methods?

It is better than the other methods of assisted hatching because it greatly reduces the physical handling of the embryo and hence ensures that it isn’t destroyed in the process. This method consists of using a specialised anodyne laser to weaken the hardened Zona Pellucida without coming in direct contact with the embryo.

Who would need an assisted hatching?

Assisted Hatching is recommended for women who have gone through the following –

  • Previous IVF or ICSI failures
  • 35 years or above
  • Have high Follicle Stimulating Hormone (FSH) levels

Is it safe?

It is the safest method among the other methods. The risks associated with it are very low and rare. It also takes only a few milliseconds to perform and is quicker.

What is the effectiveness of this method?

Among all the methods of assisted hatching, Laser assisted hatching have the highest rates of success as it involves a non-contact procedure hence eliminating the need to handle the embryo physically.


It is the safest and the best method of assisted hatching to ensure a successful implantation of the fertilized embryo on the uterine wall. While it may have some risks, the benefits far outweigh those risks and are assisted with a higher rate of success than the other methods.


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