Assisted Hatching | Doctors & treatment information

What is assisted hatching?

Artificial insemination is not always successful - even if the egg has been successfully fertilized. This is sometimes due to the fact that the resulting embryo is not able to free itself from its initial protective shell. Only then can it implant in the lining of the uterus. However, this is a prerequisite for pregnancy. Assisted hatching is a procedure that helps the embryo to break through the protective egg membrane. It is therefore a kind of hatching aid for the embryo.

From the egg cell to the hatching of the embryo

The egg cell is surrounded by a flexible but stable envelope membrane made of glycoproteins, which doctors refer to as the zona pellucida (Latin for "glass skin"). After penetration of the sperm, the zona pellucida hardens and prevents further sperm from penetrating the egg. It also protects the developing embryo from external influences.

Human egg cell with the zona pellucida surrounding it; by Henry Vandyke Carter - Henry Gray(1918) Anatomy of the Human Body (See "Book" section below) Bartleby.com: Gray's Anatomy, Plate 3, Public domain, Link

Immediately after the fertilization process, the egg cell begins to divide. After 24 hours, an embryo with four cells has already developed from one cell. The embryo then develops into an 8-cell and then a 16-cell embryo. On day 4, the so-called morula is formed, which already consists of 32 tightly packed (=compacted) cells. Five days after fertilization, the developmental stage capable of implantation follows - the blastocyst stage. In this phase, the embryo consists of over 100 cells and a fluid-filled cavity forms inside. Ready for implantation in the lining of the uterus, the embryo now begins to hatch from its protective egg membrane.

Sometimes, however, the egg membrane shows changes or is so thick that the growing embryo finds it difficult to break through. Similar to a chick that has problems breaking free from the eggshell. This is where the problem begins. Because without hatching from the shell, the embryo cannot implant in the uterine lining. As a result, the embryo dies.

This is what happens during assisted hatching

There are various techniques that help the embryo to leave the egg membrane:

• Laser technology is the most commonly used method. It allows an extremely precise and targeted procedure and is therefore considered the safest method. During treatment, the reproductive biologist uses a laser beam to open or thin the delicate egg membrane without affecting the embryo.
• Another option is to apply an enzyme solution to the zona pellucida. This causes the walls of the protective shell to become thinner. This makes it easier for the embryo to break through the vitreous membrane and implant in the uterine lining.
• A third option uses a fine glass needle, which the biologist uses to incise the zona pellucida. However, as this is done manually, success depends on the skill of the respective doctor - and is naturally associated with a higher risk.

When is assisted hatching used?

As a rule, artificial insemination treatment consists of several treatment cycles. For only 28 percent of all women, the desire to have children is fulfilled after the first treatment. Assisted hatching is by no means a standard routine method. It is only used if the woman has already undergone several unsuccessful treatment cycles with IVF or ICSI .

If the woman has not become pregnant despite successful fertilization and multiple transfers of normally developed embryos, it is possible that the embryo was not able to hatch from its shell and therefore could not implant in the uterine lining. The reason for this is usually that the egg membrane is too thick or hardened. These changes occur particularly frequently in women from the age of 37. However, the phenomenon can also be observed in eggs that were previously frozen by cryopreservation.

Is assisted hatching associated with risks?

The assisted hatching method is not entirely uncontroversial. Although various studies indicate that the procedure increases the chances of pregnancy, conclusive long-term studies are still lacking. According to current findings, assisted hatching does not affect the genetic material or the health of the future child.

However, it is not yet clear whether the method overrides a natural implantation blockade in embryos with genetic defects. Injury, and thus the loss of the embryo, cannot be ruled out either. You should therefore carefully weigh up the risks and chances of success with your doctor before undergoing treatment.

What are the costs?

Assisted hatching treatment costs between EUR 150 and 170 per embryo. As success has not yet been sufficiently proven, neither statutory nor private health insurance companies cover the costs.

Despite all doubts: For women who have already had several attempts, assisted hatching can be an option to fulfill their desire to have children after all.