Intracytoplasmic Sperm Injection (ICSI) is the process where individual sperm are selected based on their appearance and performance and then directly injected into an egg.
In the right hands this process can significantly increase the fertilization rates and increase the number of useable embryos. It is often used in cases where the sperm count is extremely low, where the motility or progression are very low, or in cases where there is a very high percentage of abnormal sperm (low morphology). In each of these cases, the chances of success with conventional IVF where a moderate number of sperm are incubated overnight with the eggs, is significantly reduced. However, with ICSI because fertilization is directly conducted, the success rates can be quite high. In the right hands, fertilization rates can be well over 90% as compared to a 50% - 60% success rate using conventional IVF. As a result, chances of success can be increased.
How is it done?
Sperm are sorted using any of the currently available techniques including swim-up, gradient centrifugation or microfluidic sorting chambers. From the highly selected pool of sperm, the embryologist painstakingly evaluates each individual sperm under a high-powered robotic microscope. Each sperm then has its tail broken to avoid any intracellular damage once injected into the egg, and the sperm head is injected via an extraordinarily thin needle into the oocyte. Fertilization then occurs and within 24 hours the embryologist can determine if the egg has fertilized and whether or not it has fertilized normally (2PN).
Should ICSI be used in all cases?
In general, ICSI is often preferable to increase the success rates. In particular, in cases where egg yield is low, or in all cases of frozen egg use, it is imperative that ICSI be used. However, there is some evolving data that suggests that ICSI may not be as useful in women who have advanced maternal age. The problem in this age group is that a lower fertilization rate also compromises the chances of having genetically normal (euploid) embryos. You should discuss your individual case with your physician and decide what best suits your specific case.
Does it have any risks?
The risks of oocyte damage are negligible. It is highly unlikely in the hands of an expert embryologist that you would experience any egg loss. However, it has been proposed that there may be an increased risk of male factor infertility in male offspring, as well as a small increase in the risk of congenital abnormalities in the offspring, though this is still highly controversial. In general, the background risk of fetal anomalies is approximately 2-3% in the general population and this number is thought to increase to 4-5% when ICSI is used representing a 1-2% increase in overall risk. However, many studies disagree with this assessment and argue that the risk of complications arises from the fact that the couple is infertile and not from the ICSI process. At present, we feel that it is extremely safe with an extremely low risk of fetal anomalies in our experience.