ICSI or Intra-Cytoplasmic Sperm Injection is today the most widely used in vitro fertilization technique in the context of medically assisted procreation. What technique is it based on? What are the stages, side effects and success rate of IVF ICSI? Panorama.

ICSI or Intra-Cytoplasmic Sperm Injection is a medically assisted reproduction technique derived from in vitro fertilization. It was developed in Belgium in 1990 by professors André Van Steirteghem and Paul Devroey. Its vocation: to allow the management of male infertility.

Conventional IVF involves culturing simultaneously in a sterile petri dish an oocyte and a certain quantity of motile spermatozoa after collection. Placed in an incubator at 37 ° C, the gametes interact with each other. Fertilization therefore takes place without other human intervention.

In ICSI, this interaction between gametes is suppressed. A spermatozoon is preselected under a microscope (magnification x 2000-4000) in order to favor the good morphology and mobility. It is then injected directly into the collected oocyte and prepared for this purpose.

IMSI is a variant of ICSI. Here, the fertilization technique is similar, but the preselection of sperm is different. The microscope used has a more powerful magnification power (x 10) in order to observe certain structural anomalies of the head of the spermatozoon. This technique is indicated to promote the implantation of the embryo and to avoid repeated miscarriages when the sperm is very strongly damaged.

ICSI is primarily recommended in cases of male infertility and more particularly:

• whether the spermograms have made it possible to identify a significant deterioration in the quality of the sperm which would make fertilization of the oocyte by the sperm difficult or even impossible. This is particularly the case in men with moderate or severe oligoastenoteratozoospermia (OATS);
• in case of azoospermia: even in the absence of spermatozoa in the semen, ICSI can be performed if a surgical sample is possible. In this case, your practitioner will assess whether an epididymal puncture (the taking of sperm from the epididymis, the duct through which semen passes) or a testicular biopsy (taking tissue directly from the testis) is possible.

However, other indications may lead your team to consider ICSI:

• in case of failure of conventional IVF (no embryo obtained) or if the number of embryos obtained in relation to the number of fertilizable oocytes following the puncture is low. We then speak of paucifecundation. In other words, if you have already had routine in vitro fertilization which was unsuccessful, your doctor may, in certain cases, recommend switching to ICSI;
• if any anti-sperm antibodies have been detected. These can be responsible for immunological infertility in humans;
• in case of pre-implantation diagnosis;
• in certain couples concerned by a particular viral context (in the event of HIV, in particular).

The ICSI protocol is more or less the same as that implemented during conventional in vitro fertilization. The only noticeable difference occurs during the fertilization phase.

• Treatment therefore generally begins with ovarian stimulation (except in special cases) in order to promote the maturation of the ovarian follicles and to be able to collect several oocytes which have reached maturity (against only one during a normal cycle);
• After the onset of ovulation, an ovarian puncture is scheduled within 36 hours. The collection of sperm is done in parallel with this sample;
• During the fertilization phase, the oocytes are selected under a microscope and prepared to rid them of their follicular cells (this is called decoronization). An equivalent number of sperm is selected, then the sperm injection is performed. A micropipette is used for this purpose to hold the oocyte in place (the retention pipette), while the sperm is injected using a micropipette dedicated to this use (the injection pipette);
• Once fertilized, the oocytes are cultured and observed for 2 days. The day following fertilization, only the oocytes which have developed two pro-nuclei are kept. On D3, when cell division has progressed (generally 4 to 8 cells), the medical team decides on the number of embryos to transfer (in agreement, of course, with you) before freezing any supernumerary embryos;
• Last step, the embryo (s) are transferred to the uterus and hormonal treatment is put in place to promote the chances of pregnancy.

The risks and side effects in the event of ICSI are limited and identical to those encountered in the event of usual IVF, namely:

• ovarian hyperstimulation;
• a multiple pregnancy linked to the implantation of several embryos;
• complications related to oocyte puncture (pain, infection).

However, there is no increased risk for the mother and the unborn baby of malformations, etc.

The ICSI technique is now the most common in assisted reproduction services. Indeed, according to the Biomedicine Agency, in 2016, approximately 2/3 of IVFs were ICSI and 34,3% of children born after medically assisted reproduction had been born using this same technique. Today, it is estimated that the success rate of ICSI is roughly similar to that of conventional IVF, with a 1 in 4 chance of achieving pregnancy in each cycle of IVF.