ICSI (from the English abbreviation ICSI - IntraCytoplasmic Sperm Injection) is a special method of female germ cells fertilization when an immobilized sperm cell is injected directly into the ovocyte using a special microinstrument.
Intracytoplasmic injection technology was developed specifically for the treatment of spermatogenesis pathology and allowed to become fathers to many males, previously considered infertile. Even the single sperm cell is sufficient for the ICSI, since only one sperm cell is needed for fertilization of an ovocyte, unlike the classical way, that needs the hundreds of thousands sperm cells. Below is the detailed information about the indications to this procedure, correct preparation to the procedure and that the results you should get.
The difference of ICSI from the classical IVF procedure
What is the difference of this method from conventional IVF? Both methods are related to assisted reproductive technologies. However, the insemination with the in vitro fertilization proceeds a more natural scenario — for fertilization, the required number of motile sperm cells are added to the cup with ovocyte media, then the process proceeds independently. Both the ICSI and classical fertilization are performed in the frameworks of the IVF program. That is why the other stages (stimulation of ovulation, transvaginal punction, growth and the embryo transfer) are the same.
Indications to the ICSI
The main indication to the ICSI are the different forms of the male infertility, the embryo absence or the low percent of the ovocyte fertilization in the previous IVF program, and the ovocyte number less than 4. However, our experience shows that using of this method allows to get more high quality embryos even in the absence of such indications.
This method of ART is performed in the following conditions:
- azoospermia + PESA/TESA/TESE or epididymis/testicle biopsy — there are no mature sperm cells in the ejaculate, but they can be detected during testicular puncture;
- oligo-, astheno-, teratozoospermia — a reduced number of sperm cells in the ejaculate, reduced mobility, morphology, or a combination of any of these diagnoses;
- retrograde ejaculation;
- a small number of full-fledged sperm cells after cryopreservation;
- lack or low fertilization rate in previous IVF programs;
- small number of ovocytes obtained;
- the need for pre-implantation genetic diagnostic (PGD);
- poor embryo quality in previous ART programs;
- intensive sperm cells agglutination and a positive MAR test;
- high white blood cell count in the ejaculate, acute or chronic bacterial infection;
- viral diseases: HIV, hepatitis B and C.
When and how is ICSI performed?
- The ovocyte is “stripped” from the surrounding follicular cells using the hyaluronidase enzyme. This is a safe procedure, because this substance is contained in the sperm cell acrosome and performs the same function under the natural conditions — it helps the sperm cell to enter to the ovocyte.
- The most mobile, morphologically “beautiful” sperm cell is selected using the magnification;
- The sperm cell immobilization is performed using the microtools. First of all it is necessary to destroy the integrity of the sperm cell membrane, so the genetic material and all the factors necessary for the activation of the ovocyte and the further normal development of the embryo turned out inside the cytoplasm of the ovocyte; secondly, the immobilization of the sperm cell is necessary for its proper localization within the ovocyte; thirdly, at the dawn of the method development such immobilization was not carried out and the results were significantly worse.
- Next, the sperm cell is recruited into a special aspiration microneedle.
- The ovocyte is fixed in the correct position using a micro-sucker so that the polar body (small accompanying cell that is a sign of ovocyte maturity) is at “6 o'clock” or “12 o'clock”.
- In the “3 o'clock” area, the shell of the ovocyte is punctured with a microneedle containing a sperm cell.
- Some volume of the ovocyte cytoplasm is aspirated through its membrane.
- The sperm cell is gently inserted into the cytoplasm of the ovocyte.
A variation of the method is ICIMNSC technology — intracytoplasmic injection of a morphologically normal sperm cell. The key difference is that the selection of sperm cell is done with great accuracy. For this a larger zoom (6300 times, while with ICSI — only 400 times), is used that allows to examine the detailed sperm morphology and choose the best sample. The ICIMNSC method allows to increase the probability of ovocyte fertilization and the onset of pregnancy.
After the procedure completion, the fertilized ovocytes are washed out and transferred to the incubator for further cultivation in a special media. The ovocyte puncture does not have the danger for the further ovocyte development because the cell has the elastic shell that quickly closes the site of injury.
ICSI procedure does not require the special preliminary measures but it is worth to mention that the success of every stage and the whole program depends from the ovocyte and sperm cell quality. That is why is recommended the urologist-andrologist consultation that should determine the treatment tactics and the medications for the sperm quality improvement. Thus, the embryologist will have a big choice of the good sperm cells. To get the highest quality ovocytes for a woman the fundamental is the right choice of stimulation, appropriate support and following the doctor's instructions. Unfortunately, there are no ways to improve the already obtained ovocytes.
Benefits of ICSI
- Method allows getting embryos and giving birth to a healthy child in case of various spermatogenesis disturbances, when classical fertilization is impossible.
- Increases the number of embryos: the percentage of fertilized cells after classical IVF is an average 70%; after ISCI, the percentage of mature cells increases to 85% and at the same time the percentage of incorrectly fertilized cells decreases. At the same time, there is practically no risk of fertilization of all or most part of the ovocytes, which is recorded in 5-10% of cases using the classical method.
- It helps to reveal rare pathology earlier, when fertilization does not occur in all cells even with the use of intracytoplasmic injection. In this case, the following protocol may use the combined method: ICSI and artificial ovocyte activation.
- Minimizes the risk of severe viral diseases, such as HIV and hepatitis transmission from father to child.
- Allows using the pre-implantation genetic diagnostic or screening of embryos without the risk of contamination by sperm cells sticking on the ovocyte, which are always present after the classical fertilization method.
- Improves the quality of embryos by selecting the best sperm cell.
- Makes it possible to assess the maturity and quality of ovocytes, since during the procedure the ovocytes are purified from the surrounding follicular cells. It is possible to track the time of the ovocyte maturation and conduct ICSI at the correct time if the ovocytes of the middle stage of immaturity are present.
- Eliminates the risk of bacterial overgrowth of the culture media in which ovocytes with sperm cells are found in the event of unexpected acute or chronic infection that exists with conventional IVF. Such toxicological load and change of the normal solution parameters, necessary for the proper development of embryos, most often leads to their degradation, poor quality and low chance of pregnancy.
- Minimizes the risk of mole pregnancy due to the correct ratio of one ovocyte — one sperm cell. Most often, the reason of mole pregnancy is the embryo obtained by the fertilization of an ovocyte by two sperm cells, which often occurs during classical insemination. An embryologist always evaluates the correctness of fertilization on the following day and rejects such embryos.
Observing all the method delicacies, the effectiveness of ICSI can reach 80%. However, for reasons beyond the control of the physician, this figure may drop to 30%; most often, this happens due to the initially poor quality of the germ cells.
There are no reliable information about any differences between children born after IVF and ICSI in the scientific literature. In addition, the experts during the research could not identify the risks that would be reliably associated with the peculiarities of the procedure. In some cases, there are no questions whether perform or not perform the ICSI — there are 100% indications for this procedure. As a rule, the question of using the method of intracytoplasmic sperm injection is solved in each specific case collectively by a doctor, an embryologist and patient.
Thus, the ICSI fertilization method is widely used in many conditions and in general has a large number of benefits. This is a technically complex and delicate manipulation, with strict requirements to the embryologist qualification and modern high-quality equipment.