Intracytoplasmic Sperm Injection - ICSI
What is Intracytoplasmic Sperm Injection (ICSI)?
ICSI is an acronym for intracytoplasmic sperm injection or to "inject a sperm into an egg".
Intracytoplasmic Sperm Injection is a very effective method to achieve fertilization in couples whose partner has decreased or "poor" sperm parameters or to "improve" fertilization rates.
The development and perfection of Intracytoplasmic Sperm Injection (ICSI) has essentially eliminated male infertility.
Eggs for Intracytoplasmic Sperm Injection (ICSI)
A standard cycle of In-Vitro Fertilization (IVF) is done and unfertilized eggs are immediately placed in an incubator with controlled levels of CO2(carbon dioxide), O2 (oxygen) and N2 (nitrogen).
After approximately 5-6 hours the eggs are checked for maturity. Only mature eggs undergo ICSI. If immature eggs are injected with sperm, they may fertilize, but do not develop normally and rarely produce an viable ongoing pregnancy.
Human eggs are one of the only species of eggs that can mature in-vitro, or in culture outside the body. By allowing the aspirated eggs to "spend" time in the incubator, some of the eggs that were not yet mature can mature in-vitro and undergo ICSI and achieve successful fertilization and normal embryo development. If the eggs are prepared for ICSI immediately after transvaginal aspiration, there is an increased chance that some will still be immature and not be able to be used, decreasing the available number of eggs that can became fertilized and produce embryos.
The Intracytoplasmic Sperm Injection (ICSI) Procedure
The Intracytoplasmic Sperm Injection (ICSI) process is complicated and requires a high level of experience and expertise to obtain high fertilization rates. At Arizona Center for Fertility Studies, our embryologist is highly skilled and averages 83% fertilization rates per case and many times achieves 90+% rates of fertilization.
The Intracytoplasmic Sperm Injection (ICSI) process is done by first identifying all mature eggs after culturing for 5-6 hours from recovery. Each egg is then gently "pick-up" by a micro-holding pipette. A single sperm is than evaluated, under high magnification, for normal morphologic characteristics, and then picked up by a second injection micropipette. Using sophisticated micromanipulators, the sperm is injected through the outer wall of the egg (zona pellucida) and egg membrane (oolema) and into the cytoplasm of the egg. The egg is placed back into the incubator.
Fertilization occurs in 4-6 hours in humans but there are no visible signs until approximately 17-18 hours later. The first signs that fertilization have occurred visibly is the development of two round bodies in the center of the egg. The slightly smaller body is the female pronucleus and contains 23 chromosomes that the egg contributes to the embryo; the other round body is the male pronucleus and contains the contribution of 23 chromosomes from the sperm. It is critical that the egg is checked at this point in time for fertilization, because over the next 6 hours or so, the two pronuclei come together in a process known as syngamy, where the two pronuclei join chromosomes, forming one nucleus of 46 chromosomes.
Within the next 6 hours, the now "fertilized egg" will divide producing a 2-cell embryo. Further division or "cleavage" takes place every 10-12 hours, producing a 4-cell embryo on day 2, an 8-cell embryo on day 3, amorula or ball of too many cells to count on day 4, and a blastocyst on day 5. If the embryo is looked at too late in this process, than "abnormal" fertilization can be overlooked and the embryo will "appear normal". This "abnormal" embryo can divide and even implant but can ever produce aviable pregnancy and is only destined to abort, resulting in a miscarriage and disappointment.
A normal egg hold by a holding pipette (left) and getting ready to be injected with a sperm in the injection pipette (right)
The microinjection pipette has penetrated the outer wall of the egg or zona pellucida and it about to penetrate the oolema or egg membrane
The injecting micropipette with a sperm inside has entered the cytoplasm or center of the egg and is ready to be injected into the egg.
Video made at Arizona Center for Fertility Studies of our embryologist preforming Intracytoplasmic Sperm Injection (ICSI)
There is no "standard of care" regarding which In-Vitro Fertilization (IVF) cases should have the Intracytoplasmic Sperm Injection (ICSI) procedure and which should not. Some clinics use it only for severe male factor, others use it on every case.
Initially, Arizona Center for Fertility Studies only did Intracytoplasmic Sperm Injection (ICSI) in cases of severe male infertility, where the sperm parameters were so poor that there was a concern that fertilization would not occur in the dish. Although, Arizona Center for Fertility Studies always gives a couple the choice as to whether or not they want to do Intracytoplasmic Sperm Injection (ICSI), and every couple understands that if their partner has normal sperm parameters, they may have very good fertilization rates without Intracytoplasmic Sperm Injection (ICSI); because of Arizona Center for Fertility Studies very high fertilization rates with Intracytoplasmic Sperm Injection (ICSI), most patients will elect to do Intracytoplasmic Sperm Injection (ICSI) rather than conventional in-vitro fertilization in a dish. This gives them the maximum chance of having as many embryos as possible, so as to be able to pick the "best" ones for transfer and have enough good embryos leftover to cryopreserve for future attempts and/or additional children without having to undergo the egg stimulation process again.
Pregnancy rates have been shown to be as good as or slightly better with Intracytoplasmic Sperm Injection (ICSI) than with conventional in-vitro fertilization in a dish. This success, however, is almost solely based on the experience and expertise of the embryologist and the circumstances of each individual case. To date, there is little or no evidence showing any adverse effects on the pregnancy and long term studies do not indicate any adverse effects on children born from eggs that underwent Intracytoplasmic Sperm Injection (ICSI). Currently there are no reports of increased birth defects or congenital abnormalities in babies born through Intracytoplasmic Sperm Injection (ICSI). A theoretical concern is that since Intracytoplasmic Sperm Injection (ICSI) allows a sperm to cross the egg barrier, that might not have been able to do so on its own, this could allow the transfer of certain male infertility conditions that have a genetic basis in a resulting male offspring.