The embryo produced in the fertilization procedure is covered and protected for the first few days is called the zona pellucida. The Zona Pellucida is a glycoprotein layer enclosed in the plasma membrane of mammalian oocytes. The phenomenon by which the blastocyst or the embryo comes out of the zona pellucida is called hatching and is a crucial event for successful reproduction. For its development, an embryo must attach itself to the inner lining of the uterus. For that to happen, hatching must first take place. The zona pellucida also ensures that only one sperm enters the egg to fertilize it. Moreover, it keeps the cells of the embryo together.
Sometimes it happens that the egg shell or the zona pellucida hardens due to which it becomes difficult for the embryo to hatch and attach to the uterus. Internal factors like age, Follicle Stimulating Hormone (FSH) diagnosis and treatment, modifications in the hormonal levels and external factors like the IVF culture environment are the possible reasons for the abnormal hardening of the shell, making hatching difficult. Apart from that, because of some in vitro culture conditions, the secretion of zona lysin which helps in hatching gets affected. Due to this, the zonapellucida hardens.
To help the embryo to hatch out of the egg in case there is some difficulty in hatching, some techniques are used. These methods are called assisted hatching techniques. In assisted hatching, the zona pellucida is artificially breached or thinned to help in the hatching process. This procedure helps in overcoming the internal or external barriers in the ART (Assisted Reproductive Technology) fertilization methods. Assisted hatching also improves the hatching rates of embryos thereby increasing the chances of pregnancy.
Several different assisted hatching techniques are used, including drilling by acidic Tyrode’s solution, partial mechanical zona dissection, piezo- micromanipulation and laser drilling. Among these different techniques, laser drilling has proven to be the most efficient, effective and the safest too. Laser drilling or Laser Assisted Hatching (LAH) method uses a laser to weaken a portion of the zona pellucida so that it becomes easy for the embryo to hatch out of the egg and to attach itself to the uterus lining.
The laser used to weaken the shell of the egg is non-contact which implies that the laser doesn’t come in direct contact with the embryo. The opening of embryo is weakened with the assistance of laser. The entire technique is done with careful precision and delicacy. This system enhances and increases pregnancy rates among women. Laser Assisted Hatching takes strikingly less time and protects the embryo from various chemicals so the collaborative impact of these advantages decreases the pressure on the embryo amid the procedure. The system additionally guarantees that the embryo is less susceptible to physical exploitation.
During the cleavage stage where the division of cells of the zygote takes place, the zona pellucida in the in vitro culture of the human embryo gets harder, mainly due to the environmental conditions. In IVF, the egg is taken out for micro insemination which removes it from its natural environment. This makes for quicker hardening of the egg shell than natural. This also happens for women of age more than 37 years giving birth. Similarly, women who have been treated with high doses of FSH, tend to produce eggs with harder zona pellucida. Because of a harder shell, the egg is unable to hatch easily or may need a lot of energy to do so thereby not being able to attach to the woman’s uterus.
Laser Assisted Hatching is implemented and found to be useful in the following cases:
- Women of age more than 37 years hence producing eggs with a harder zona pellucida
- Women who have failed previous IVF or ICSI cycles
- Women with a high level of Follicle Stimulating Hormone (FSH)
- Women who are taking frozen embryo transfer
Not many researches have looked at different techniques of assisted hatching, yet no less than two investigations have recommended that laser assisted hatching is a more secure option acid drilling with acid Tyrode’s solution. Embryologists prefer the laser assisted hatching in the way described, as it permits the quickest and clearly minimum invasive way to deal with breaching the zona pellucida. It is a system that isn’t just simple to become proficient, yet in addition, can be reliably applied in an effectively quantifiable way.
Some latest studies demonstrated that women who have endured multiple failed IVF cycles, double their odds of a pregnancy by utilization of laser assisted hatching. The probability of enhanced chances for pregnancy is evaluated restoratively before prescribing laser assisted hatching.
At Aveya IVF, we offer laser assisted hatching for women who have sustained multiple IVF treatments without getting pregnant, as well as in situations where the woman is more than 37 years old. We additionally prescribe that thawed embryos are treated with laser assisted hatching. We offer laser assisted hatching, which is a safe and gentle way to weaken a part of zona pellucida. When the laser assisted hatching is done and the embryo successfully hatches out of the egg, we transfer it into the woman’s womb.