Intracytoplasmic Sperm Injection (ICSI): Human Fertilization 


What is Intracytoplasmic Sperm Injection (ICSI)?


In order 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 can not 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 center of the egg. After using the traditional IVF or ICSI, the fertilized egg develops in a laboratory for 1 to 5 days prior to transferring it into the woman’s uterus. 


Why Would Someone Need ICSI?

ICSI is a good method that helps to overcome fertility problems, such as:

  • The sperm may not swim in a normal movement.
  • The sperm may have problems attaching to the egg.
  • In vitro matured eggs are used for fertilization.
  • The male partner provides very few sperm to do artificial insemination.
  • Previously frozen eggs are being used for fertilization.
  • Eggs could not be fertilized by the traditional IVF, no matter what the condition of the sperm is. 
  • A blockage in the male reproductive tract could prevent the sperm from getting in.


Will ICSI Work?

ICSI can fertilize 50% to 80% of eggs, however, there could be some problems take place during or after the ICSI process:

  • Some or all of the eggs could be damaged
  • The egg could not develop into an embryo even after injecting it with a sperm
  • The embryo could stop developing


Once the fertilization is done, the couples have an equal chance of giving birth to one baby, twins or triplets the same way they have IVF with or without ICSI. 


How Is Sperm Collected for Use in ICSI?


The sperm may be retrieved through normal ejaculation for men whose sperm have low mobility or are very low. ICSI makes the most cost-effective option for treating fertility for men with vasectomy, microsurgical vasectomy reversal. Needle aspiration or microsurgical sperm make good alternatives when a competent microsurgical vasectomy fails, or if the male partner refuses the surgery. It also helps physicians to easily and quickly collect acceptable numbers of sperm for the ICSI process.  


A tiny needle is used to obtain the sperm directly for the tests. Needle aspiration is a simple procedure performed under sedation, however, it could cause pain or swell later on. The sperm retrieved from the testis is only suitable for ICSI procedures when the testicular sperm could not penetrate the egg itself.


Can ICSI affect a baby’s development?

There is a 1.5% to 3% chance that the baby conceived naturally may have a major birth defect. On the other hand, the chance defected with ICSI is similar to IVF, but kind of a little higher than the condition in natural conception. The higher risk of birth defects could be because of infertility and not the treatment used to cure it. 


Are There Specific Conditions where ICSI Is Actually Recommended? 

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. Azoospermia is a medical condition where the male’s ejaculation does not have sperm and it could be in two types: obstructive and non-obstructive.

Obstructive azoospermia may happen due to any of the following:

  • Previous vasectomy
  • Congenital absence of the vas
  • Scarring from previous infections.


Non-obstructive azoospermia takes place when a defective testicle is not producing sperm. At this point, the probability of retrieving usable sperm is low, and the potential of using donor sperm may be considered.


In Vitro Fertilization (IVF) and Intracytoplasmic Sperm Injection (ICSI) are the most popular fertility treatments. The main difference between IVF and ICSI is the method of sperm fertilizing the egg. 

In IVF, the egg and sperm (they could be multiple) are placed together in a laboratory dish on their own. On the other hand, ICSI, only one sperm is directly injected inside the egg. 


IVF or ICSI, How to Choose? Which Makes a Better Option for You? 

ICSI will make a better option if the male partner has sperm-related infertility problems. For the main reason that ICSI is the most popular successful treatment for male infertility where the sperm is given an extra support. Therefore, the doctor may see ICSI a better chance if the man has any of the following:

  1. A low sperm count
  2. An abnormal sperm mobility
  3. Obtaining the sperm surgically


On the other hand, IVF is also a commonly used and successful fertility treatment which is proper for a wide number of people and a vast variety of infertility problems. Therefore, there are different types of IVF for each age and condition. For example, the ABC IVF criteria is a perfect choice for women at or under the age of 37. 


What Health Concerns Come Along with ICSI?

There are recent studies suggesting that developing babies from pregnancies operated via artificial insemination and ICSI, in particular, could face a higher risk for some birth defects, for example, imprinting defects. Imprinting defects point out to the phenomenon where certain genes operate differently.


Reproductive researchers tend to think that manipulation of either gametes or zygotes could affect the imprinting process. While others believe that the frequency of these birth defects happening is similar to the ones in a natural pregnancy. The possible risks from operating an ICSI should be discussed with the couple’s reproductive specialist. 


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