What is intracytoplasmic sperm injection
(ICSI)?
In human
being formation of an embryo from a woman’s egg and a man’s sperm is a very
complex phenomenon. The sperm of a man is a moving cell inside the body and it
must reach to the egg at appropriate time to fertilize it as the released egg
from ovary can survive for only 24 hours. At times this process doesn’t happen
due to any of following problems in the man
1. Sperm quantity may be too low –
oligospermia
2. Azoospermia- No sperms are found
3. Defects in sperm movement –
Asthenospermia
4. Sperm cannot penetrate the egg due
to a thick covering – thick zona
Before a
man’s sperm can fertilize a woman’s egg, the head of the sperm must attach to
the zona of the egg. Once attached, the sperm penetrates through the outer
layer to the inside of the egg (cytoplasm), where fertilization takes place.
Sometimes
the sperm cannot penetrate the outer layer, for a variety of reasons. The egg’s
outer layer may be thick or hard to penetrate or the sperm may be unable to
swim. In these cases, a procedure called intracytoplasmic sperm injection
(ICSI) can be done to fertilize the egg inside the labaoratory. During ICSI, a
single sperm is injected directly into the cytoplasm the egg.
How ICSI is different from IVF?
There are
two ways that an egg may be fertilized in the laboratory: IVF and ICSI. In
traditional IVF, 50,000 or more swimming sperm are placed next to the egg in a
laboratory dish. Fertilization occurs spontaneously when one of the sperm
enters into the cytoplasm of the egg. In the ICSI process, a tiny needle,
called a micropipette, is used to inject a single sperm into the center of the
egg. Fertilization achieved through ICSI can be up to 80-90% whereas through
IVF it is aound 50 -60 %. With either traditional IVF or ICSI, once
fertilization occurs, the fertilized egg (now called an embryo) grows in a
laboratory for 2 to 5 days before it is transferred to the woman’s uterus
(womb).
Why ICSI is needed?
ICSI helps
to overcome fertility problems, such as:
• The male
partner produces too few sperm to do artificial insemination (intrauterine
insemination [IUI]) or IVF.
• The sperm
may not move in a normal fashion, hence cannot reach up to the egg in time.
• The sperm
may have trouble attaching to the egg , Intra cytoplasmic sperm injection
overcomes this.
• Azoospermia
due to a blockage in the male reproductive tract may keep sperm from getting
out. In these couples the sperms are obtained directly from Testes through a
minor procedure like PESA or TESE. ICSI helps these couples to achieve a
pregnancy even though no sperms are found in semen analysis.
• At times,
traditional IVF fails to create embryos in some patients. ICSI can achieve
fertilization in such patients regardless of the condition of the sperm.
• ICSI is
used along with IVM (In vitro maturation of eggs).
• ICSI is
necessary where frozen eggs are used for fertilization.
Does ICSI work for all?
ICSI
fertilizes up to 80% of eggs. But certain issues may occur during or after the
ICSI process:
• Some or
all of the eggs may be damaged. Hence it is advisable to take help of an expert
embryology department.
• The egg
might not grow into an embryo even after it is injected with sperm. This can
happen due to any inherent problem in any one of the couple.
• The
embryo may stop growing after fertilization due to several reasons.
Once
fertilization takes place, a couple’s chance of achieving pregnancy is same for
IVF and ICSI. Chances of Pregnancy in humans is up to 30-40 % even with very
good embryos. This is due to the low implantation capacity of human uterus.
Can ICSI affect a baby’s development?
If a woman
gets pregnant naturally, there is a 1.5% to 3% chance that the baby will have a
major birth defect. The chance of birth defects associated with ICSI is similar
to IVF, but slightly higher than in natural conception.
The
slightly higher risk of birth defects may actually be due to the infertility
and not the treatments used to overcome the infertility.
Certain
conditions have been associated with the use of ICSI, such as
Beckwith-Wiedemann syndrome, Angelman syndrome, hypospadias, or sex chromosome
abnormalities. They are thought to occur in far less than 1% of children
conceived using this technique.
Some of the
problems that cause infertility may be genetic. For example, male children
conceived with the use of ICSI may have the same infertility issues as their
fathers. Couple should go through a counselling process at a standard ICSIcenter with the help of Infertility specialists and embryologists.
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