During ICSI just one sperm is injected directly into the egg cytoplasm using a micromanipulative apparatus that transforms imperfect hand movements into fine and precise movements of micromanipulation tools.

Intracytoplasmic Sperm Injection (ICSI) is an assisted reproductive technique (ART) initially developed by Dr. Gianpiero D. Palermo in 1993 to treat male infertility. It is most commonly used in conjunction with in vitro fertilization (IVF). Following IVF procedure, the physician places the fertilized egg into the female’s uterus for implantation. Sperm are obtained by the same methods as with IVF: either through masturbation, by using a collection condom, or by surgically removing sperm from a testicle through a small incision (MESA, TESE). The females are treated with fertility medications for approximately two weeks prior to oocyte retrieval to stimulate superovulation, where the ovaries produce multiple oocytes rather than the normal one oocyte. The oocytes are retrieved by either laparoscopy, or more commonly, transvaginal oocyte retrieval. In the latter procedure, the physician inserts a thin needle through the cervix, guided by a sonogram and pierces the vaginal wall and then the ovaries to extract several mature ova. Before the embryologist can inject the sperm into the oocyte, the sperm must be prepared by washing and exposing it to various chemicals to slow the sperm movement and prevent it from sticking to the injection plate. Also, the oocytes are treated with hyaluronidase to single out the oocyte ready for fertilization by the presence of the first polar body. Then, one prepared sperm is injected into an oocyte with a thin needle. Often, embryologists try to fertilize several eggs so they can implant more than one into the uterus and increase the chance of at least one successful pregnancy. This also allows them to save extra embryos, using cryopreservation, in case later IVF rounds are needed.

After the embryologist manually fertilizes the oocytes, they are incubated for sixteen to eighteen hours and develop into a pronucleate eggs (successfully fertilized eggs about to divide into an embryo). The egg then grows for one to five days in the laboratory before the physician places it in the female’s uterus for implantation.

The chance of fertilization increases dramatically with ICSI compared to simply mixing the oocytes and sperm in a Petri dish and waiting for fertilization to occur unaided (classical IVF procedure). Studies have shown that successful fertilizations occur 50% to 80% of the time. Since the introduction of ICSI, intrauterine insemination (IUI) has decreased in popularity by 80%.

ICSI is more effective method than spontaneous fertilization. In many centres it is preferred  to minimize the risk of “zero fertilization” which is frequent even in normospermic men.

This method is very successful mainly in the following cases:

  • abnormal semen analysis findings ie. low sperm concentration (oligospermy), a high level of abnormal sperm with low motility (asthenopermy) or high rate of the spermatozoa with abnormal morphology (therathospermy),
  • fertilization using sperm surgically extracted from testicles or the epididymis (using MESA/TESE/PESA etc. techniques)
  • failure of spontaneous fertilization in the previous treatment IVF cycles despite of normospermic findings (i.e. the sperm values of spermiogram are considered as normal by WHO standards)

In these situations, suboptimal spermatozoa could by-pass the physiological check-points of natural fertilization and generate embryos, and subsequently babies. Conventional ICSI has the hypothetical risk of injecting immature, DNA damaged, aneuploid, low motile, morphologically abnormal, zona binding deficient, poor acrosome reacted, spermatozoa. Nowadays, we have no real knowledge of the effects of suboptimal sperm selection on ICSI adults in the long term, at least for humans. A potentially worrying aspect of the injection of DNA damaged spermatozoa for example, has been suggested by studies performed on animals which showed not only a negative effect on pregnancy and birth, but also later side effects on the health of adult animals such as aberrant growth, premature ageing, abnormal behaviour, and mesenchymal tumours.

The recent refinements of the ICSI procedure are reliable, easy-to do, non-invasive and in some cases “closest to the nature” than the conventional procedure. For example, selecting spermatozoa prior to ICSI by their maturation markers such as HAZP receptors it is possible at very least to mimic nature in order to restore physiological selection and prevent hypothetical fertilization by DNA damaged and chromosomal unbalanced spermatozoa. In addition, non-invasive imaging sperm selection techniques such as IMSI or sperm head birefringence can be valid tools for helping in selection of the ideal spermatozoa. In fact, sperm selection based on non invasive morphology or maturity markers helps the embryologist in selection of the “ideal” spermatozoa to inject. These new advances in ICSI may allow the selection of the spermatozoa contributing to improve: fertilization, embryo quality, blastocyst formation, pregnancy rate and reduction in abortion. 

Sperm fragmentation test is genetic selection. A sperm DNA fragmentation test can tell you whether there’s any DNA damage to be found among your partner’s sperm.
With the fragmentation test, you can look at the cells themselves to determine what percentage of sperm have fragmentation, which basically means “damage.” Less than 15 percent damage usually means a very good outcome, while 16 to 29 percent can mean a less rosy outlook, though still pretty good. If more than 30 percent of the sperm show fragmentation, it may prove very difficult to get and maintain a healthy pregnancy, even if you are doing IVF.
DNA damage can increase with age, so a man in his 50s or 60s may have a higher percentage of sperm fragmentation. Other factors — such as exposure to various chemicals or toxic agents, excessive heat, chronic infections in the prostate, chemotherapy, radiation or smoking — can also be to blame. On the positive side, there’s some hope that antioxidant vitamins can help minimize the damage.
This test is not for direct use the sperm, and ICSI. Sperm for fertilization are already unusable. It does not help to improve embryonic development.

Methods for improving the outcome of ICSI:

  • IMSI - Intracytoplasmic Morphologically Selected Sperm Injection, high magnification, motile sperm organellar morphology examination. Method helps to choose better quality sperm for ICSI. Correlating the presence of vacuolar with degeneration of the sperm.
  • PICSI - Petri-dish Intracytoplasmic Sperm Injection, binding to hyaluronic acid as an indication of sperm maturity, method helps to choose better quality sperm for ICSI. Mature, biochemically competent sperm bind to the hyaluronan where they can be isolated by the embryologist and used for ICSI. This procedure mimics a key step in the natural fertilization process, the binding of mature sperm to the oocyte complex. As a result, the selected sperm is essentially the same as one that would be successful in the natural reproductive process.
    The research proved that hyaluronan-bound PICSI-selected sperm are, in the vast majority of cases, more mature, exhibit less DNA damage, and have fewer chromosomal aneuploidies.
    PICSI method to be a biologically more natural and effective form of fertilization in comparison to ICSI, because only those sperm are chosen for fertilization that are able to form a bond with the oocyte cumulus complex, i.e. only mature sperm are selected.

             This method is suitable for everyone but we highly recommend it especially in the following cases:

             – previous total failure or low fertilization even after ICSI

             – low embryo quality or their failure to develop

             – repeated abortions

  • MACS - Magnetic-Activated Cell Sorting, Magnetic nanoparticle-based selection of live sperm with integral (not fragmented) DNA. Method helps to choose better quality sperm for ICSI.
  • SCSA/SDIA - Sperm Chromatin Structure Assay/Sperm DNA Integrity Assay, Fluorescently-based determining the percentage of sperm with fragmented DNA and the degree of DNA damage. Sperm for fertilization are already unusable.

ICSI safe and effective therapy for male factor infertility, but may carry an increased risk for the transmission of selected genetic abnormalities to offspring through the increased inherent risk of such abnormalities in parents undergoing the procedure but not due to the procedure itself.  

The follow-up studies on ICSI children have demonstrated the safety of this technique although a slight increase of chromosome aberration seems to be caused by the injection of aneuploid spermatozoa.

 ICSI offers fertilization and pregnancy rates comparable or higher to that achieved with normal sperm quality for couples who have failed to achieve fertilization on repeated IVF cycles or have severe impairments in semen quality. In addition, the success of ICSI was independent of standard semen parameters (density, motility, and morphology).

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New Advances in Intracytoplasmic Sperm Injection (ICSI) ―by Parmegiani et al. licensed under CC BY 3.0
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