ICSI
Intra Cytoplasmic Sperm Injection (ICSI)
Intra Cytoplasmic Sperm Injection (ICSI) is a procedure by which a single sperm is inserted with the aid of a micro needle into the cytoplasm of a mature oocyte. This procedure is recommended for severe cases of male factor infertility, unexplained infertility or low fertilization rates after conventional IVF. ICSI is conducted as a part of a cycle in which the ovaries of the female partner or egg donor are stimulated with hormones to increase the production of oocytes. Mature oocytes are removed from ovaries using mild sedation and an ultrasound guided needle via transvaginal aspiration in a hospital amphitheater or in an outpatient facility. The oocytes are then identified, separated from the follicular fluid and their maturity is assessed in the laboratory. The mature oocytes are injected individually using a glass holding pipette to secure the egg and a very small micro needle through which the sperm is inserted. The injected eggs are subsequently placed in culture medium and fertilization is determined 12-18 hours later.
Technically, the ICSI technique is a precise and delicate procedure. It requires state of the art equipment, well trained and skilled personnel, and attention to detail. In the hands of experienced personnel more than 80% of the oocytes should be fertilized with ICSI and less than 5% of those injected are lost at the time of injection. The pregnancy rates are comparable to conventional IVF. As more research is conducted with this technique it is projected that the results are going to improve the outcome of infertility therapy in the future.
The introduction and widespread application of assisted reproductive techniques (ART) on patients that otherwise are not able to reproduce have raised concerns regarding the outcome of the resulting pregnancies as well as the offspring’s health. Others have suggested that since several stages of natural fertilization are usually bypassed while early embryonic development takes place in vitro, some abnormalities or disorders may be induced as a result of the short time the embryos spend in the laboratory. Apart from the potential risk of genetic defects, malformations and other adverse outcomes for children born as from ART, others fear that the type of fertilization (natural, conventional in vitro fertilization, or ICSI) may have an effect on the obstetric and perinatal outcome as well. However, no reports have been published analyzing the effects of the condition leading to IVF or ICSI on the rate of abnormalities in resulting children.
Overview of Conditions Where ICSI is Often Employed:
Male Infertility- Low sperm count
Abnormally shaped sperm
Male or Female antisperm antibodies
Frozen sperm obtained surgically
Prior IVF failure
Prior poor fertilization
Small number of retrieved eggs
Advanced female age and infertility
The Efficiency of ICSI
It is obvious that ICSI is applied to cases where conventional IVF or other forms of therapy will show limited success. Therefore, we are not going to try to compare conventional IVF vs ICSI. What we rather do is to offer some statistics compiled from our own experience and published clinical or scientific articles. In general, the overall fertilization rates with ICSI show a mean of 75% (>60% being acceptable), while the mean clinical pregnancy rates are 55 % (>40% being acceptable). Emphasis has been placed on determining if the origin where sperm are retrieved from plays any role on the outcome. The fertilization and clinical pregnancy rates according to the retrieval sites of sperm are as follows:
Site of retrieval |
Fertilization rate |
Clinical Pregnancy Rate |
Ejaculated |
75.6% |
45-65 % |
Epididymus |
72.6% |
47- 67 % |
Testicular |
63.1% |
20-40 % |
The Safety of ICSI
Considering that ICSI gives a chance to conceive their own genetic children to patients who otherwise would not be able to conceive has raised the question of safety. The issue of safety in ICSI has two sides, one that is immediate: destruction of the egg at the moment of injection; and another that is of long term in nature: passing genetic abnormalities to the offspring.
Immediate dangers of ICSI.
Although ICSI is not a perfect technique, fortunately, the destruction of eggs at the time of injection is in most cases well below the 5% level in experienced laboratories. Some eggs have plasma membranes that are too elastic and difficult to pierce, or in other cases the eggs may be too old and fragile so that they are destroyed at the time of injection. As we continue to improve the tools and injection techniques, it is estimated that the proportion of eggs destroyed at the time of injection will be even lower in the future. There are no effective strategies to limit the number of defective or aged oocytes. Following strict ovarian stimulation protocols to avoid too short or too long cycles and ensuring that uniform cohorts of follicles are developing at near physiological rates may be the best approach to improve oocyte quality. Any defective eggs will continue to be destroyed at higher rates than normal oocytes.
Long term dangers of ICSI.
It is reassuring to know that several thousands of babies have been born all over the world after ICSI procedures had been employed. In a US study involving over 2000 babies there was a 1.8% incidence of congenital abnormalities at birth. Of those 1.1% was major and 0.7% was minor abnormalities. While in a similar cohort of conventional IVF patients there was a 3.5% incidence of congenital abnormalities, where 2% were major and 1.5% was minor. These babies have been followed closely and have yet to show a significant higher incidence of somatic abnormalities than in-vitro or naturally conceived babies. However, other reports from Australian researchers suggest that the incidence of abnormalities in “ICSI babies” may be greater than in those born after natural conception or derived from conventional IVF. A great effort has been made by the ESHRE Task Force on ICSI and the International Working Group for Registers on Assisted Reproduction to collect information on ICSI. The ESHRE Task Force Report for the period from 1993-1995 reported that the incidence of major and minor malformations was not greater than those following IVF or natural conception (2.2%), whereas the sex chromosomal aberration rate was slightly increased (2%). This increase may be attributed to the inheritance of paternally derived chromosomal abnormalities, but it may also be due to de-novo chromosomal abnormalities. Another report on over 3000 ICSI babies showed an incidence of 2.7% of abnormalities, rates that are comparable with those found in natural conception.
Although the data mentioned above may reassure clinicians and parents as well that there is not a great difference in abnormalities among babies conceived after IVF, ICSI or natural conception, we should not overlook that patients with certain genetic abnormalities may have a greater risk of passing them on to their offspring. It has been long suspected that chromosomal abnormalities (Chromosomally Derived Sterility) are implicated in some forms of male infertility. Up to 20% of male infertility can be explained by abnormalities in chromosomes. A review of the literature of somatic chromosome investigations in infertile males has shown that 13.7% of severe oligozoospermic males have abnormal chromosomes or karyotype. Therefore, a genetic factor may be affecting gamete formation or function. In normal fertile males the mean frequency of chromosomal abnormalities in spermatozoa is about 10%. The first cytogenetic studies on spermatozoa of infertile males were first published about 2 years ago. The results show a highly significant increase (10 fold) in the frequencies of chromosomal abnormalities compared with normal fertile patients. Cytogenic studies in spermatozoa (non-somatic cell) indicates that advanced age (>40 years) has been associated with structural chromosome abnormalities in fertile males as well.
Infertile couples electing Advanced Reproductive Technologies should be counseled on the cause of their infertility and the “genetic transmission” risks when ICSI is performed. If a male partner carrier of a constitutional chromosome aberration the rate of ICSI success is lowered, increases the risk of miscarriage. In addition, in ongoing pregnancies in the presence of a chromosome aberration, multiple congenital abnormalities and/or mental retardation are possible. With sex chromosome aneuploidy (e.g.: 47, XXY or 47, XYY) the success rates are variable, and the risk of aneuploidy in the offspring is probably low or unknown. In cases of structural aberrations of a sex chromosome, there is a greater risk of transmitting infertility, depending on the position of the breakpoint in the chromosome.
In some cases of male infertility there may be a small risk of passing medical conditions to the offspring. This may be the case of ICSI performed after vasectomy or immunologic infertility. However, patients with congenital absence of the vas deferens (CAVD) or non-motile spermatozoa must be tested further and given appropriate genetic counseling due to Cystic Fibrosis or Kartagener’s Syndrome respectively. Unilateral Absence of the vas deferens and Young’s Syndrome are conditions with features similar to CAVD. Whether these patients have an increased risk of children born with these syndromes is not known. Recent research indicates that some seminal traits such as low sperm counts are related to genes located in the Y chromosome. The American Society for Reproductive Medicine (ASRM) recommends that all male patients with sperm counts lower than 5 million should be tested for Y chromosome deletions.
Intra-cytoplasmic Spermatid injection and ICSI with other extreme cases of male factor infertility. We are not going to focus on the probability of finding spermatids, which is very low, or on the probability of achieving fertilization, pregnancy and eventually a new born baby. Instead, we would like to create awareness on the fact that extreme cases of male infertility may not be the main condition but a symptom of another probably undiagnosed and more serious problem that could be passed on to your offspring. Then, finding the real cause(s) of the problem leading to infertility may be the main task of your reproductive endocrinologist and other specialists. Focusing your attention on how to achieve a pregnancy with your own gametes at all costs and leaving aside the task of finding the cause(s) of your inability to achieve a pregnancy may not be the best alternative. However, we have to accept that in some cases the medical field does not have answers for everything. Therefore we may reach a dead end and may have to proceed forward with the information available. Fortunately, for some patients, there is the option of using donor semen coupled with intrauterine inseminations which opens the possibility of achieving a pregnancy at much lower cost and with a lower risk of child malformations.
The indications for ICSI
Severe male factor infertility may result from one or more in semen specimens.
These include:
1. Very low numbers of normal motile sperm. Which include: low seminal volume, low motility, low sperm counts, high percentage of abnormal spermatozoa or a combination of two or more of any of these factors.2. Problems with sperm binding and penetrating the oocyte. Characterized by failed attempts of conventional fertilization in vitro, sperm antibodies, or zona pellucida defects.
3. Frozen sperm collected prior to cancer treatments that may be limited in number and quality.
4. Lack of spermatozoa in the ejaculate may be due to congenital absence of the vas deferens or blocked vas deferens (vasectomies, infections of the reproductive tract) require PESA/TESA to obtain the sperm which are then used to fertilize the oocytes through ICSI.
5. Low number of oocytes retrieved. In some cases the number of oocytes obtained is so low that if they are inseminated in a conventional manner (Conventional IVF) some of them may have to be discarded due to lack of fertilization or because more than one sperm penetrated the egg. To circumvent this problem, some advocate the use of ICSI to ensure that a low number of eggs are penetrated by one sperm only.
The risks of this procedure are:
- Some eggs may be destroyed at the time of injectio.
- Even if we inject a sperm into the egg (assuring sperm penetration) there is no assurance that the eggs will be activated and show signs of fertilization. Therefore, when you are faced with a low number of eggs and are asked about using ICSI to ensure fertilization, remember that either Conventional IVF or ICSI may be equally effective or disastrous depending on the hands of the operator. We at SEMERT advocate the use of ICSI when four or fewer eggs are obtained. Our skilled laboratory personnel make the difference.
6. Rescue ICSI. This is a term that describes when ICSI is applied to non-fertilized eggs the day after Conventional IVF. In our hands, this procedure has always failed to produce fertilization for two main reasons.
- Failed fertilization after conventional IVF is a rare occurrence in our laboratory. Therefore, we have had a couple of cases only in which we have experienced no fertilization. In all cases where we observed no fertilization, we were able to track the causes for this event to moderate cases of flu or fever during the ovarian stimulation phase of the cycle or to patients with very low prognosis for fertilization due to poor response or age.
- In addition, there is a biological reason to dismiss “rescue ICSI” as a solution to the lack of fertilization. Unlike the sperm, the oocytes have a limited “shelf life”. If an egg is not fertilized within 6 hours after ovulation it quickly becomes aged and loses the ability to fertilize and evolve into a healthy embryo after fertilization. Therefore, once we determine that the eggs are not fertilized by conventional means, typically 14-18 hours after insemination or 20-24 hours after retrieval, it may be too late to attempt the rescue of the oocytes with ICSI. Even if we achieve fertilization after “rescue ICSI”, it may be too late for the egg to develop into a normal embryo. We may be able to transfer a few embryos of marginal quality, but the probability of pregnancy may be near zero. From an emotional and economic standpoint it does not make sense to drag your hopes and finances in a losing battle. How do you avoid failed fertilization after conventional IVF? Certainly, we may not be able to assure that all couples will have fertilized eggs. Some, even after finding normal seminal parameters and having nice looking oocytes, may have abnormalities at the molecular level that may impair fertilization. However, we may be able to decrease the probability of failed fertilization with a systematic work-up prior to an ART cycle, coupled with reliable testing on you and the male partner and using the therapies that most fit your needs. To summarize, “rescue ICSI” is not a viable solution to failed fertilization after conventional IVF.
Conclusions and recommendations.
Based on the information published so far, we can conclude that patients should be informed that depending on the infertility condition(s) when using ICSI: there may be a higher risk of transmitted chromosomal aberrations, a risk of “de-novo” mainly sex chromosome abnormalities and a risk of transmitting fertility problems to the offspring. Patients also may be reassured that there seems to be no increased risk of congenital malformations. However, this is not to imply that later in life some other conditions may develop. Considering the benefits and potential risks of ICSI, it may be necessary to have a number of recommendations in place and to limit as much as possible, negative consequences on the offspring and the couple:
1. Complete medical and genetic screening of potential parents;
2. Minimum standards for semen and genetic screening for patients with severe cases of male factor infertility;
3. Minimum standards for patients with idiopathic or unexplained infertility;
4. Conservative use of ICSI;
5. Informed consent of the patients;
6. Expert medical and genetic counseling in cases of severe male factor infertility;
7. Long term follow-up of children born after ICSI;
8. Increase efforts worldwide to evaluate and study the effects of ICSI on the health of the offspring in a more coordinated and structured manner.