ICSI or Intracytoplasmic sperm injection is a laboratory procedure developed to
help infertile couples undergoing assisted reproduction due to male factor infertility.
ICSI, a form of micromanipulation, involves the injection of a single sperm directly
into the cytoplasm of a mature egg (oocyte) using a glass needle (pipette).This
process increases the likelihood of fertilization when there are abnormalities in
the number, quality, or function of the sperm. ICSI is generally unsuccessful when
used to treat fertilisation failures that are primarily due to poor egg quality.
Before ICSI can be done, mature eggs must be retrieved from the female partner during
a standard IVF cycle. The male partner's semen sample is prepared in the lab to
isolate as many healthy moving sperm as possible. After allowing the eggs to rest
for 4-6 hours following their removal, the tight outer coating of cells (cumulus)
is removed from each egg. Only then can we be sure the egg is mature enough to undergo
ICSI.
Immature eggs cannot be injected. However, they can be incubated for a further 4-18
hours and reassessed. If they mature during that time and sperm is still available,
they can undergo delayed injection. Fertilization rates with delayed injection are
not as good as with usual ICSI techniques. A special instrument is used to hold
the egg in place. It is so small you can barely see the tip with the naked eye.
A thinner, sharp, needle-like instrument is used to pick up a single normal appearing
sperm. With great precision, the needle is inserted through the egg's outer coating
(the zona pellucida) and into the egg itself. The sperm is slowly injected into
the egg, and the needle is removed, leaving the sperm behind. The injected eggs
are placed in an incubator overnight and checked the next morning for signs of fertilization.
- Very low numbers of motile sperm.
- Severe teratospermia (abnormal sperms).
- Problems with sperm binding to and penetrating the egg.
- Antisperm antibodies thought to be the cause of infertility.
- Prior or repeated fertilization failure with standard IVF methods.
- Frozen sperm limited in number and quality.
- Obstruction of the male reproductive tract not amenable to repair. Sperm may then
be obtained from the epididymis by a procedure called microsurgical epididymal sperm
aspiration (MESA), or from the testes by testicular sperm aspiration (TESA).
Fertilization occurs in 50% to 80% of injected eggs. The ICSI process may damage
a small percentage of eggs. The fertilized egg may fail to divide, or the embryo
may arrest at an early stage of development. Approximately 30% of all ICSI cycles
performed result in a live birth, which is comparable to rates seen with traditional
IVF. Younger patients may achieve even more favourable results. Factors such as
poor egg quality and advanced maternal age may result in lower rates of success.
ICSI does not increase the incidence of multiple gestations as compared to standard
IVF. Because ICSI is a relatively new technique, first performed in 1992, long-term
data concerning future health and fertility of children conceived with ICSI is not
available. To date, there is no convincing evidence that the incidence of birth
defects is any different with ICSI or IVF as compared to those children born to
other parents of similar age and health. This is an area of ongoing investigation.
Because some causes of male infertility are familial and are related to genetic
problems, male offspring might have reproductive problems as adults. Despite these
concerns, ICSI is a major advance in the treatment of severe infertility.