Intracytoplasmic sperm injection (ICSI) is a form of micro-assisted fertilization, suitable mainly for cases of severe male infertility.
Intracytoplasmic sperm injection is an IVF procedure in which a single sperm cell is injected directly into the cytoplasm of an egg. This technique is used in order to prepare the gametes for the obtention of embryos that may be transferred to a maternal uterus. With this method, the acrosome reaction is skipped.
ICSI microinjection or intracellular sperm injection has been successfully used around the world since the early 1990s and is a truly effective pregnancy therapy that allows many infertile couples to have their own child.
When to apply to ICSI?
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.
- The sperm may have trouble attaching to the egg.
- A blockage in the male reproductive tract may keep sperm from getting out.
- Eggs have not fertilized by traditional IVF, regardless of the condition of the sperm.
- In vitro matured eggs are being used.
- Previously frozen eggs are being used.
How the ICSI technique is performed
After sperm collection, depending on the number and motility of the sperm, the treatment is applied to activate them, with small modifications. If the sperm sample is not enough, the partner is asked to give a second, additional sample a few days later. If the sperm contains even a few dozen motile sperm, micro-fertilization can be performed normally.
Similar to conventional in vitro fertilization, the ICSI micro-fertilization process presupposes that ovaries have been stimulated with fertility drugs in order to produce many mature eggs. After being absorbed, the eggs are then subjected to a special “treatment” with an enzyme (hyaluronidase) to remove the granular cells that surround them. This is necessary otherwise, they will not be able to penetrate the sperm, as in ICSI the sperm is injected and not by themselves as is the case with conventional IVF. This “treatment” takes 1-2 minutes and once the eggs are free of the granulocytes, it is possible to assess which ones are mature and suitable for ICSI and which ones are not.
The final step in the ICSI procedure is to immobilize one egg at a time with the help of a thin glass pipette and with another thinner glass pipette (which resembles an injection needle) to isolate each sperm and then insert it into the cytoplasm of each egg. Each “introduction” takes a few seconds, but the whole process can take many hours, especially if the sperm are scarce and difficult to find.
After the “import” process is completed, the eggs are re-placed in special culture materials until they are fertilized and embryos are produced.
The method is completed, following the well-known procedure of in vitro fertilization: after the formation of blastocysts, the embryos are selected, and finally the embryo transfer.
Success rates of the method
The success of the ICSI technique depends on several factors, such as:
- sperm viability
- the quality of the eggs
- the effective activation of eggs
- the egg’s ability to withstand the intracellular plasma process
The percentage of successful pregnancies per attempt with the ICSI technique is 65-75%. The possible factors that can affect the success rates in the course of pregnancy and consequently the completion of the birth with ICSI micro-fertilization, are similar to those of conventional in vitro fertilization.