Intracytoplasmic sperm injection (ICSI) is an assisted reproduction technique used in in vitro fertilisation (IVF) treatment by which one sperm is injected directly into an oocyte to fertilise it while improving the patient’s possibilities of becoming pregnant.
ICSI is mostly used in cases of male infertility caused by low sperm count or motility. This technique is also indicated when the semen sample was vitrified before its use.
The most common signs of male infertility:
- An insufficient number of viable sperm, known medically as oligozoospermia or criptozoospermia
- Severe reduction of sperm motility or no motility at all (asthenozoospermia)
- A high number of abnormally-shaped sperm (teratozoospermia)
- Complete lack of sperm in the ejaculate caused by a testicular obstruction (obstructive azoospermia)
- Complete lack of sperm in the ejaculate caused by a defect in sperm production (secretory azoospermia)
- Retrograde ejaculation (anejaculation)
- Insufficient semen sample: when there is only a small volume of vitrified sample left
Less frequently, this technique is also used in cases of female infertility when there is an insufficient number of eggs or they are of low quality.
With the ICSI technique, a microscope and micromanipulation tools are used (micromanipulator, microinjector and micropipettes). The mature egg is kept in place with a holding pipette while a gentle suction is carried out with a microinjector. A single sperm is selected with a micropipette.
The egg is perforated and the sperm is release into the egg. Once the process is completed, the egg is placed into a cell culture and put in an incubator, where it remains controlled in order to ensure fertilisation.
As is the case of conventional in vitro fertilisation or any other assisted reproduction treatment, there are no absolute guarantees of pregnancy. Some of the factors that can affect the success rates when ICSI is used are DNA fragmentation levels, an advanced maternal age and sperm quality.