When is ICSI Used ?
If there are even a small number of sperm in the
ejaculate, (or if sperm are affected severely by
antisperm antibodies during their maturation process)
sperm can be taken from a semen sample for ICSI. If
there are no sperm in the ejaculate, due to an obstruction
or to very low sperm production, sperm can now be
surgically retrieved directly from the testes or the
epididymis (TESE, PESA). Because it is the genetic
information carried in the head of the sperm that needs
to get into the egg, immature sperm whose tails have not
fully developed are adequate for use in ICSI. ICSI
is also sometimes used if there is an apparent problem
with fertilization in an IVF cycle. In summary, ICSI
helps bypass almost all sperm problems in infertile men
such as azoospermia (zero sperm count), oligozoospermia
(low sperm counts), asthenozoospermia (poor sperm motility),
teratozoospermia (too many abnormal sperms) and also patients
of retrograde ejaculation or anejaculation (where
electroejaculation and IUI have failed to give a pregnancy).
How is it done?
This procedure is very specialized, and requires a
great deal of skill on the part of the scientist.
All the procedures require the use of special microscopes
and micromanipulation equipment. To put it in perspective,
an egg is approximately one-tenth of a millimetre across!
The egg is gently held with a suction pipette (on the left
in the picture below) while a sperm is picked up with a
microinjection needle, and deposited in the cytoplasm of
the egg. By doing this, several barriers to the sperm have
been removed, and fertilization usually follows. The day
after injection, we can tell whether fertilization has
taken place if there are two small spheres (pronuclei)
visible in the egg. If fertilization is successful, the
pre-embryo (zygote) is allowed to divide several times in
culture medium in the laboratory, before it is transferred
to the uterus or fallopian tube. Any "spare" good embryos
resulting from the procedure can be frozen for more attempts
later. To summarize the ICSI process:
- 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 egg) and in to the cytoplasm of the egg.
- The sperm is injected in to the cytoplasm and the needle carefully removed. The eggs are checked the next morning for evidence of normal fertilization
What is the success rate like?
ICSI has similar success rate to IVF (about 32%
of embryo transfer procedures produce a clinical
pregnancy). IVF has a slightly higher pregnancy
(about 36%), although this might be explained by
the problems inherent in some cases to the sperm
generally used in ICSI procedures. Frozen embryo
transfers after ICSI also have a similar success
rate to those after IVF (about 29%). These results
do vary with female age, with a substantial fall
in pregnancy rates in women over the age of 38.
What about the babies born by ICSI?
At the current moment, available research suggests that ICSI and IVF born children are normal. There is no increased risk of any anomalies or developmental delays in offspring born from these techniques. Stray reports which appear in the press may be related to children born from these techniques in the older age group which is at a higher risk for such anomalies (age related and not technique related)