What is ICSI?

Intracytoplasmic sperm injection (ICSI) can be used as part of an in vitro fertilisation (IVF) treatment to help you and your spouse to conceive a child.
ICSI is the most successful form of treatment for men who are infertile and is used in nearly half of all IVF treatments. ICSI only requires one sperm, which is injected directly into the egg. The fertilised egg (embryo) is then transferred to your uterus (womb).



is an assisted reproductive technique used to overcome the following infertilityproblems:

  • Regarding male infertility: it is used in cases of azoospermia, oligozoospermia, criptozoospermia, asthenozoospermia, teratospermia, oligoasthenozoospermia, oligoasthenoteratozoospermia, men who underwent vasectomy, men with an infectious disease (HIV, hepatitis, etc.), men who have frozen their sperm before undergoing radiotherapy or chemotherapy, or failure of ejaculation under normal conditions.
  • Regarding female infertility: if a low number of oocytes is obtained after follicular puncture or egg retrieval, or if the zona pellucida is very thick after oocyte retrieval, or in cases of poor egg quality.
  • Repeated failure to achieve pregnancy after several cycles of conventional in vitro fertilisation.
  • Egg fertilisation failure using conventional IVF.
  • Microinjection of unfertilised oocytes using conventional IVF.
  • In-vitro maturation of immature oocytes.
  • When a Preimplantation Genetic Diagnosis (PGD) is required in cases of couples with some genetic alteration or when it is necessary to know which ones are genetically normal embryos.
  • In cases of immune infertility with a low number of antisperm antibodies and after repeated failure of previous artificial insemination cycles, or in cases of immune infertility with a high number of antisperm antibodies.


The ICSI process includes some steps from the in vitro fertilization (IVF) process. The only difference is the way in which oocyte insemination is performed.

The ICSI process step by step is as follows:

  • Controlled ovarian stimulation: a series of hormones are administered so that the woman’s ovaries produce more than one mature oocyte. Moreover, this hormonal supplement also helps controlling the exact date when the menstrual cycle will start.
  • Follicular puncture: also known as egg retrieval, it consists of removing the mature oocytes by means of follicular puncture guided by ultrasound.
  • Sperm collection and preparation: a lower amount of sperm than IVF is required for ICSI, since it will be the biologist who, by means of a microscope with a micromanipulation system, will choose the ideal spermatozoon. If there are too many spermatozoa in the sample, it is counterproductive because it makes it more difficult to choose the one which is going to be injected.
  • Your spouse may produce a sperm sample himself by ejaculating into a cup on the same day as your eggs are collected. If there is no sperm in his semen, doctors can extract sperm from him under local anaesthetic. Your doctor will use a fine needle to take the sperm from your spouse’s:
    • epididymis, in a procedure known as percutaneous epididymal sperm aspiration (PESA), or
    • testicle, in a procedure known as testicular sperm aspiraction (TESA)

    If these techniques don’t remove enough sperm, your doctor will try another tactic. He’ll take a biopsy of testicular tissue, which sometimes has sperm attached. This is called testicular sperm extraction (TESE) or micro-TESE, if the surgery is carried out with a microscope.

  • Oocyte insemination: the ideal sperm is chosen and then the ICSI process is conducted. The spermatozoon is inserted inside the oocyte with a needle.
  • Embryo culture: embryo development is evaluated and recorded.
  • Embryo transfer: it is usually performed on day 3 of embryo development, although it can also be done on day 5 if a PGD is required or in cases where previous failure has occurred.
  • Embryo freezing: if more than a single healthy embryo exists, they are frozen in order to be used in further treatments.

How long does ICSI treatment last?

One cycle of ICSI takes between four weeks and six weeks to complete. You and your spouse can expect to spend a full day at the clinic for the egg and sperm retrieval procedures. You’ll go back anywhere between two days and six days later for the embryo transfer procedure.

What are the success rates of ICSI?

The success rates for ICSI are higher than if you use conventional IVF methods. A lot depends on your particular fertility problem and your age. The younger you are, the healthier your eggs usually are, and the higher your chances of success.

The percentage of cycles using ICSI which result in a live birth are:

  • 35 per cent if you are under 35
  • 29 per cent if you are between 35 and 37
  • 21 per cent if you are between 38 and 39
  • 14 per cent if you are aged between 40 and 42
  • six per cent if you are between 43 and 44
  • five per cent if you are over 44

What are the advantages of ICSI?

  • ICSI may give you and your spouse a chance of conceiving your genetic child when other options are closed to you.
  • If your spouse is too anxious to ejaculate on the day of egg collection for standard IVF, sperm can instead be extracted for ICSI.
  • ICSI can also be used to help couples with unexplained infertility, though experts haven’t found that ICSI makes pregnancy any more likely than standard IVF.
  • ICSI doesn’t appear to affect how children conceived via the procedure develop mentally or physically.

What are the disadvantages of ICSI?

  • ICSI is a more expensive procedure than IVF.
  • ICSI has been in use for a shorter time than IVF. So experts are still learning about its possible effects.
  • The same risks associated with standard IVF procedure, such as multiple births and ectopic pregnancy, apply to ICSI.
  • You may have a higher risk of congenital conditions such as cerebral palsy in your baby. The risk rises from three per cent for naturally conceived children to about six per cent after IVF or ICSI. One large study found a higher rate of abnormalities in ICSI babies when compared with IVF babies. But this risk is still low.
  • During natural conception, only the hardiest sperm manage to travel great distances and break through the membrane of an egg to fertilise it. Weaker sperm don’t make it. But because ICSI bypasses this natural selection process, there’s an increased risk of rare genetic problems carried by the sperm being passed on to the child. Some but not all genetic problems can be tested for before you have the treatment.
  • ICSI is a more expensive procedure than IVF.


PICSI (Physiological ICSI)

PICSI is a variation of the ICSI technique where the P stands for physiological.

In the traditional ICSI the selection of the spermatozoon is made by the embryologist who observes the sperm sample and selects a spermatozoon with good motility to carry out the ICSI.

By means of the physiological ICSI or pICSI it is intended to find a less subjective system in the sperm select system. This variation of the ICSI is carried out using a similar molecule that surrounds the oocyte naturally.


This assisted reproduction technnique is rather new, so it is still being studied which patients should be the most appropriate to undergo this technique. However, fertilityclinics have decided that the use of this technique is indicated in cases of:

  • Patients whose spermatozoa have a high degree of DNA fragmentation.
  • Previous ICSI failure caused by low-quality embryos.
  • In cases of repeated miscarriage where the cause might be the man’s sperm or it can be unkown.


The pICSI procedure is the same as that of the ICSI. It only changes in the selection of the male gamete.

The sperm collection is made as usual. After the sperm capacitation, the spermatozoa are placed in a special plate 

This plate contains some drops of a synthetic material very similar to hyaluronic acid that naturally covers the oocytes. The best-quality spermatozoa will get stuck to these drops, so the embryologist will be able to easily identify them and used them for the ICSI.

Once the spermatozoon has been selected, it is aspirated with the microinjection pipette and the regular ICSI is performed.


This method is very useful in cases of patients with sperm with good motility and ahigh degree of DNA fragmentation because they help to choose the mature spermatozoon with a good quality.

These spermatozoa are selected individually and present low rates of fragmentation which can help reduce the possibility for any genetic alterations such as aneuploidy.

In this way, the chance for good-quality embryos to form is higher which leads to a rise in the pregnancy rates.