For an embryo to implant into the lining of the uterus, it essentially must divide to where it forms a multicellular embryo with a liquid cavity (blastocyst). This blastocyst is coated with a gel-like material called ‘Zona’ or ‘Zona Pellucida. In order for the blastocyst to implant in the uterus, its cells must pass through the Zona. This process is known as hatching.

Very often, this hatching ability of the blastocyst by IVF or ICSI is impaired. This is when assisted hatching comes in handy. It is a laboratory procedure in which the Early Embryo Zone is chemically or mechanically weakened in a way that helps the embryo to hatch more easily, allowing implantation into the lining of the uterus. This technique was first developed by Dr. Jacques Cohen at Cornell University in New York in 1990, and has since been adopted by various IVF clinics around the world. It is also now widely accepted that assisted hatching improves implantation rates in certain patients undergoing IVF, ICSI, or both.

Who should consider assisted hatching?

• Age factor; especially when the female partner is older than 37 years

• Quantity and quality of eggs; when the woman’s day 3 follicle stimulating hormone (FSH) level is high, or with a low antral follicle count or low AMH level

• Embryo quality factor; poor-quality embryos with slow rates of cell division or excessive fragmentation

• Factor Zone; when the embryos have a thick Zona Pellucida or a thick outer layer

• Previous IVF failures; with women who have had one or more previous failed IVF cycles

IVF assisted hatching

One of the most frustrating aspects of IVF for both patients and professionals is coping with failure, especially for couples who have tried ART procedures multiple times. Assisted hatching helps cope with such difficulties for couples who are also running out of time. After observing that embryos with thin ZP had higher implantation rates, it was postulated that creating a minor defect in ZP would eventually increase the chances of the embryo hatching. This was a boon for women who faced multiple IVF cycle failures due to a thicker Zone shell preventing hatching. In addition, assisted hatched embryos are implanted one day earlier, allowing a greater opportunity for implantation, especially in cases where the endometrium is advanced due to ovarian stimulation. However, this additional manipulation in the laboratory implies a small risk of damage to the embryo during the micromanipulation and transfer processes, along with a slight increase in identical twins. However, the size of the defect is critical in this procedure and can produce unwanted results.

Types of assisted hatching

There are four types of assisted hatching techniques currently practiced by ART specialists around the world.

1. Partial dissection of the area Also known as mechanically assisted hatching, partial site dissection involves briefly holding the embryo in position using gentle suction. The microneedle passes through ZP in the larger perivithelin and proceeds tangentially. Subsequently, the embryo is released from the holding pipette after creating a cross-shaped indentation. Subsequently, the embryos are returned to culture 7 stored until transfer.

2. Hatching assisted by acid Tyrode A defect is created in the Embryo Zone by using a mouth-controlled delivery system to blow Tyrode acid onto the outer surface. The embryos are subsequently rinsed several times to wash off excess acid before returning to standard culture media and stored until transfer.

3. Laser hatching In this method a computer controlled non-contact mode is used to pierce the Zone. Laser assisted hatching involves specific software designed to allow easy embryo positioning, focusing and measurement along with simple laser alignment. The laser is also arranged with three preset low, medium and high energy intensities that can deliver a single pulse with a single mouse click to pierce the Zone based on specific requirements.

4. Hatching assisted by pronase thinning of the Zona Pellucida A dilute solution of pronase is used in this procedure. The embryos are transferred to a solution of pronase in G2 medium under oil for initial stretching and softening of ZP. The goal of this method is to dilute ZP without removing it completely. Later they are observed under the microscope to obtain results, the embryos are incubated more with pronase if necessary. These embryos are then transferred to fresh G2 medium and washed twice before placing in the incubator until transfer.

Success rates of assisted hatching

It is important that assisted hatching be performed by properly trained expert embryologists for success. Actual live birth rates for this ART procedure will differ from one IVF clinic to another. As female fertility declines with age, the younger you are, the greater the chances of success. Research suggests that this procedure is no more likely to cause abnormalities than IVF without assisted hatching.

Assisted hatchery treatment facilities in India

India is a specialized global destination for IVF procedures. Travcure’s healthcare consultants partner with the best ART hospitals in the country, including Fortis Bloom IVF Center, Bourn Hall Fertility Clinic, and Apollo Hospitals Center for Assisted Reproduction. Also, surrogacy laws in India are quite lenient and IVF packages in India with Travcure medical tourism are low cost and generally affordable.