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About
Laser Assisted Hatching
A covering layer, or 'shell'
surrounds embryos or blastocysts
called the Zona Pellucida (ZP).
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. It also
acts to prevent premature implantation
in the Fallopian tube and may
help prevent the early embryo
from being attacked by cells
of the immune system.
The embryos have to "hatch"
or break out of the zona in
order to embed into the endometrium
lining the uterine cavity. This
occurs about four to five days
after embryo transfer when the
embryo is at the blastocyst
stage. Naturally this takes
place by expanding/contracting
of the zona until it distorts,
allowing the blastocyst to "hatch".
If
the zona is not functional,
this hatching may not occur.
It has been reported that up
to 75% of normal embryos never
hatch through the protective
layering of the zona. Laboratory
techniques involved in IVF may
result in hardening of the zona.
In natural fertilization there
are enzymes present within the
fluid in the Fallopian tube,
which may "soften"
the zona. This does not happen
in IVF as the tube is bypassed.
The zona may also be thicker
following IVF, especially in
older ladies. Frozen embryos
may also have a hardened zona.
Methods
of Assisted Hatching
Chemical
This involves chemicals (acid
tyrodes) used to produce a weakened
area of the zona. The chemical
is applied through a microtool,
manipulated by an embryologist.
It is not entirely accurate,
as when working with such small
amounts of chemicals, it is
hard to quantify the dose with
pinpoint accuracy. The acid
then has to be washed off in
order to prevent further damage
to the embryo.
Laser The zona is drilled by
the microlaser system called
Fertilase. It creates a clean-cut
precise incision in the zona.
This is more accurate for several
reasons: • The process
is fast compared to the chemical
method, thus the embryo does
not have to be held still by
a suction pipette. As well as
this factor, we use a vibration
free table to avoid any accidental
movement of the embryo.
• The accuracy of the
laser is predetermined by its
programming, and is therefore
not dependent on the skill of
the operator. There is a high
degree of reproducible accuracy.
Who
is suitable for Laser Assisted
Hatching?
At the Delhi-IVF Centre patients
who will be considered for laser
assisted hatching are: •
Those patients who have IVF
or ICSI who are over 37 years
• Patients having Frozen
Embryo transfer.
• Patients who have had
a previous failed IVF or ICSI
treatment cycle
• Patients undergoing
IVF/ICSI for the first time,
who are considered poor responders
because they have required a
high dose of gonadotrophins
for poor ovarian response
• Patients who in an earlier
IVF cycle have had a low fertilisation
rate, for example, less than
one third of the embryos achieving
fertilsation
• Patients with three
or less embryos
• Patients who request
laser assisted hatching and
are fully informed of its use
and function
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