Intracytoplasmic sperm injection (ICSI, pronounced “Ik-see”) was designed as a treatment for male factor infertility, but these days it has many different indications. ICSI involves injection of a single sperm into an egg that has been harvested for the purpose of in vitro fertilization (IVF).
The first baby born from ICSI was in 1992 and since that time ICSI has revolutionized the treatment of infertility worldwide. Currently, ICSI is used in 60 to 100% of IVF cycles, depending on which area of the world you have your fertility treatment.
Infertility affects about one in six couples, and male factor is the single most common cause. There are many different problems that can affect a man’s sperm, some of these are genetic, but in most cases the cause is never determined. If the sperm count is low (oligozoospermia) or they do not swim well (asthenozoospermia) then the sperm will not be able to make it through the woman’s uterus and fallopian tube to reach the egg for fertilization. Abnormally shaped sperm (teratozoospermia) may have trouble swimming and/or penetrating the shell of the egg.
Before the availability of ICSI, standard IVF was used for more than 10 years. Standard IVF means that a woman’s eggs are stimulated with hormones and then harvested from the ovaries and placed in a dish (in vitro is Latin for ‘within the glass’). More than one hundred thousand sperm are then ‘sprinkled’ on each egg and the dish is placed in an incubator. This means that the sperm must compete for the egg and fertilization occurs in a similar way to what happens in a woman’s body. When the sperm count is not perfect however, standard IVF can result in a very low number of eggs being successfully fertilized. From there, the resulting embryos (egg + sperm = embryo) do not all develop normally, and furthermore every normal embryo does not lead to a healthy pregnancy. I tell patients that it takes a lot of eggs just to make one successful embryo!
ICSI means that instead of hoping the sperm makes it into the egg on its own, an embryologist would pick the healthiest looking sperm from a sample and inject it directly into the egg. To say it simply, with ICSI the sperm doesn’t have to swim or break through the eggshell, it just has to show up inside the egg. It is not currently possible to test the DNA inside the sperm to make sure it is normal before using it, so the embryologist chooses based on appearance. Even sperm with abnormal shapes (morphology) can be used to create a healthy baby. The packaging of the sperm does not necessarily reflect its genetic potential. In men who have no sperm at all in the ejaculate (azoospermia) a surgical procedure can be used to extract sperm directly from the epididymis or testicle (TESE or microTESE) which can be used for ICSI. Fertility clinics must be highly specialized to offer this procedure. Using the techniques of microTESE and ICSI, azoospermic men (who prior to 1992 would not have been able to have a genetically-related child) are now able to have a family.
Embryologists require years of training and experience to properly perform ICSI. An anti-vibration table keeps the micromanipulation tools steady while the sperm is suctioned into a tiny needle and then injected through the egg’s shell (oolemma). Factors that can affect the success of embryos beyond this point include a woman’s age, egg quality, and sperm DNA quality.
A 2012 committee opinion from the American Society for Reproductive Medicine (ASRM) concluded that ICSI is best used for male factor infertility, frozen eggs, couples with previous failed fertilization and preimplantation genetic testing.
ICSI is considered to be safe for the couple and the resulting child. There have been over a million babies born from IVF worldwide. The earliest babies are now into adulthood and having children themselves. The large majority of studies on IVF suggest that infertility itself, rather than the process of IVF, is largely the cause of adverse outcomes after fertility treatment. But, this does not account for all birth defects.
Babies born from men with very low sperm counts who required ICSI may have a 1 – 2% increase in birth defects, which includes future low sperm counts in the male babies. The most significant risk factor for birth defects after IVF is actually pregnancy with multiple babies (twins, triplets, etc). The good news is that this is preventable. Worldwide, clinics are working to reduce the number of embryos transferred at once, in order to lessen this risk. It is important to keep in mind that human biology is never perfect. Birth defects occur in more than 3% of all pregnancies, even when they are naturally conceived.
In summary, the availability of ICSI has transformed the lives of many men whose sperm count would never otherwise have allowed them to have a baby of their own. In the hands of a highly experienced fertility clinic, ICSI is not harmful to the sperm or the egg and it can help couples get the maximum number of embryos during their IVF cycle. Although it was initially developed for male factor infertility, it now has many other indications to optimize fertilization.
Remember that every couple is unique and your fertility doctor can best advise you on whether standard IVF versus ICSI is the right decision for you.