Assisted zona hatching is a procedure of

assisted reproductive technology Assisted reproductive technology (ART) includes medical procedures used primarily to address infertility. This subject involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), and cryopreservation of ga ...

, mainly used in IVF, which assists

zona hatching Implantation, also known as nidation, is the stage in the mammalian embryonic development in which the blastocyst hatches, attaches, adheres, and penetrates into the endometrium of the female's uterus. Implantation is the first stage of gestatio ...

. To achieve this a small hole is made in the

zona pellucida The ''zona pellucida'' (Latin meaning "transparent zone") is the specialized area surrounding mammalian oocytes (eggs). It is also known as an egg coat. The ''zona pellucida'' is essential for oocyte growth and fertilization. The ''zona pelluc ...

(mechanically, chemically or by laser) to facilitate hatching.IVF-infertility.com
/ref> Zona hatching is where the

blastocyst The blastocyst is a structure formed in the early embryonic development of mammals. It possesses an inner cell mass (ICM) also known as the ''embryoblast'' which subsequently forms the embryo, and an outer layer of trophoblast cells called the ...

gets rid of the surrounding zona pellucida to be able to implant in the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

Efficacy

A systematic review and meta-analysis came to the result that assisted zona hatching is related to increased rates of clinical pregnancy and multiple pregnancy in women with previous repeated failure or frozen-thawed embryos. However, it is unlikely to increase clinical pregnancy rates when performed in fresh embryos transferred to unselected women, to those without poor prognosis or to women of

advanced maternal age Advanced maternal age, in a broad sense, is the instance of a woman being of an older age at a stage of reproduction, although there are various definitions of specific age and stage of reproduction. The variability in definitions is in part e ...

. Also, overall, there no evidence of a significant difference in

live birth rate Pregnancy rate is the success rate for getting pregnant. It is the percentage of all attempts that leads to pregnancy, with attempts generally referring to menstrual cycles where insemination or any artificial equivalent is used, which may be simpl ...

following assisted hatching compared with no assisted hatching.

Indications

Sometimes, some embryos have a thickened or deformed zona pellucida that makes it difficult for them to come out and, therefore, can lead to implantation failures. To avoid this, this technique can be used. Assisted hatching is not routinely done in all laboratories. It is recommended in some cases: • Patients of advanced age (37 years or more) • Implantation failure • Anomalous zona pellucida (thick, partitioned,...) • Thawed embryos since vitrification produces a hardening of the zona pellucida. • Embryos with slow development. For example, when on day 3 they have less than 6 cells. • To do a blastocyst biopsy Those embryos biopsied to make PGD (preimplantation genetic diagnosis) will already have the hole made and, therefore, will hatch easily once they reach the stage of expanded blastocysts. https://www.reproduccionasistida.org/assisted-hatching/#indicaciones

Methods

Mechanical assisted hatching: involves the use of micromanipulation techniques by using a needle. The zona pellucida is pierced with a needle and drilled by friction against a pipette. It is a technique that is rarely used because of the risk it has of damaging the embryo. It is also called "partial zona dissection". Chemical assisted hatching: involves the use of specialized solutions (mostly acid, e.g. thyroid acid) in order to degrade the

. Because it can be toxic for the embryo, it needs to be washed. "Laser assisted hatching" (LHA): a high energy laser is used to create an opening in the

, it is the most precise technique and safe for the embryo but it is the most expensive one.

References

Assisted reproductive technology Human reproduction {{med-tech-stub