Naturally, the fertilisation process involves the penetration of a single sperm from the ejaculate
into the egg (called oocyte in scientific terms) released during the menstrual cycle. Said sperm
must penetrate the shell of the oocyte (called zona pellucida) to immediately fuse with the female
gamete.
Sometimes, either due to physiological deficiencies that may lead to a drastic reduction or
absence in the production of gametes or due to poor gamete quality or defects in the interaction,
the process of fertilisation can be diminished or even prevented.
From the Assisted Reproduction Techniques (ART) perspective there are two main approaches
to overcome these deficiencies:
1. Conventional In Vitro fertilisation (IVF)
2. Intra Cytoplasmic Sperm Injection (ICSI)
What is Intracytoplasmic Sperm Injection (ICSI)?
So that a man’s sperm can fertilize a woman’s egg, the sperm’s head has to attach the external
part of the egg. Once the sperm is attached, it starts to push through the external layer to the
internal layer of the egg (cytoplasm) where fertilization happens. In some cases, the sperm
cannot penetrate the egg or become unable to swim especially when the external layer of the egg
is thick. In these cases, Intracytoplasmic sperm injection ICSI, which is a procedure along with
in vitro fertilization (IVF), needs to be done.
How Does ICSI Work?
In traditional IVF, around 50,000 or even more swimming sperm are put next to the egg in the
laboratory. Fertilization takes place when the sperm reaches the internal cytoplasm of the egg.
On the other hand, in the ICSI procedure, a tiny needle called micropipette is used to inject one
sperm inside the centre of the egg. After using the traditional IVF or ICSI, the fertilized egg
develops in a laboratory for 1 to 5 days before transferring it into the woman’s uterus.
Who is this for?
The indications of conventional IVF and ICSI are a tubal factor, uterine factor, premature
ovarian failure, ovulatory dysfunction, endometriosis, diminished ovarian reserve and
unexplained infertility. ICSI is especially recommended for samples presenting alterations in the
semen analysis (mostly in cases of low concentration or motility), situations in which there are a
limited number of oocytes available or in cases of previous fertilisation failures with
conventional IVF. This leads conventional IVF to be usually indicated in good prognosis patients
were the quality of both gametes is not an apparent limitation.
Will ICSI Work?
ICSI is based on the insertion of a selected sperm into the oocyte, overcoming the limitations that
conventional IVF faces with poor semen samples and deficiencies in the interaction between the
gametes. Because of this, ICSI has become the most commonly used IVF technique. With the
help of an advanced micromanipulation station (including microscope, microinjectors and
micropipettes) the sperm has to be individually selected and immobilised. During the
microinjection, the oocyte has to be held while the sperm is inserted and released inside the inner
part of the oocyte. The day after the microinjection, signs of proper fertilisation will be checked
in each oocyte.
ICSI could be recommended if there is suspicion of a certain reason making the fertilization
difficult. ICSI is used for couples who have male infertility factors. These factors could include
any of the following: low sperm, poor movement, poor quality, the inability of penetrating an
egg or azoospermia.
ICSI has been a tremendous benefit to IVF for over a decade and has revolutionized the
treatment for couples that have diagnosed with low sperm count, low sperm motility or low
sperm morphology. At Aaradhya, we discuss with the couples and then go ahead with the
procedure.
