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Intracytoplasmic sperm injection is commonly
referred as – ICSI. It is a simple
way of saying “inject sperm into egg.” ICSI is a very effective method to
fertilize eggs in the invitro-fertilisation (IVF) lab after they have been
aspirated from the female. Its main use is for significant male infertility
cases.
IVF with ICSI involves the use of specialized
micromanipulation tools and equipment and inverted microscopes that enable
embryologists to select and pick up individual sperm in a specially designed
ICSI needle.
The needle is carefully advanced through the outer
shell of the egg and the egg membrane – and the sperm is injected into the
inner part (cytoplasm) of the egg.
This usually results in normal fertilization in
about 75 to 85 per cent of eggs injected with sperm.
However, first the woman must be stimulated with
medications and have an egg retrieval procedure so we can obtain several eggs
for in vitro fertilization and ICSI.
Who should be treated with intracytoplasmic sperm
injection?
There is no ‘standard of care’ in this field of
medicine regarding which cases should have the ICSI procedure and which should
not.
Some clinics use it only for severe male factor
infertility, and some use it on every case. The large majority of IVF clinics
are somewhere in the middle of these 2 extremes.
The thinking about ICSI has changed over time, and
experts are now doing more ICSI (as a percentage of total cases) than was done
between 10 and 12 years ago. As experts learn more about methods to help
couples conceive, the thinking will continue to evolve.
Common reasons used for performing ICSI
These include; severe male factor infertility that
do not want donor sperm insemination. ICSI is also used on couples with
infertility with sperm concentrations of less than 15 to 20 million per
millilitre and on males with low
sperm motility – less than 35 per cent; very poor sperm morphology (subjective
– specific cut-off value is debatable)
ICSI can also be used where there have been previous IVF with no fertilization – or
a low rate of fertilization (low percentage of mature eggs that were normally
fertilized).
Sometimes it is used for couples that have a low
yield of eggs at egg retrieval. In this scenario, ICSI is being used to try to
get a higher percentage of eggs fertilized than with conventional insemination
of the eggs (mixing eggs and sperm together).
How is ICSI performed?
The mature egg is held with a specialized holding
pipette.
A very delicate, sharp and hollow needle is used
to immobilize and pick up a single sperm.
This needle is then carefully inserted through the
zona (shell of the egg) and in to the center (cytoplasm) of the egg.
The sperm is injected in the cytoplasm and the needle
is removed.
The eggs are checked the next morning for evidence
of normal fertilization.
Fertilization and pregnancy success rates with
ICSI
IVF with ICSI success rates vary according to the
specifics of the individual case, the ICSI technique used, the skill of the
individual performing the procedure, the overall quality of the laboratory, the
quality of the eggs, and the embryo transfer skills of the infertility
specialist physician.
Sometimes IVF with ICSI is done for “egg factor”
cases – low ovarian reserve situations. This is when there is either a low
number, or low “quality “of eggs (or both).
In such cases, ICSI fertilization and pregnancy
success rates tend to be lower.
This is because the main determinant of IVF
success is the quality of the embryos.
The quality of the eggs is a crucial factor
determining quality and viability of embryos.
In some cases, assisted hatching is done on the
embryos prior to transfer, in order to maximize chances for pregnancy.
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