Standard insemination or ICSI: What is the best way to fertilize your eggs?
Until their egg retrieval, many women feel relatively in control of their IVF cycle. During the preparation for IVF and the injections, the eggs are growing comfortably in your ovaries. However, once the eggs are retrieved, the IVF laboratory takes over fertilization of your eggs and care of your embryos. Relinquishing control can be difficult, but you should feel comfortable about what is happening “behind the scenes.”
One big decision is how to inseminate, or fertilize, your eggs. There are two main choices: standard insemination or intracytoplasmic sperm injection (ICSI). In standard insemination, each egg is placed in an individual droplet in a dish and surrounded by thousands of sperm, allowing them to fertilize on their own. For standard insemination, the sperm need to be plentiful and motile. In ICSI, an embryologist looks through a high-powered microscope and selects the most healthy-looking sperm and then injects one sperm into each egg using a fine needle. For ICSI, much lower numbers and quality are acceptable because the sperm are being directly injected and do not have to swim to or penetrate the egg naturally.
ICSI was first performed in 1987, and the first child from ICSI was born in 1992. The original indication for this technique was to overcome severe sperm problems, where the quantity and/or quality of sperm is not sufficient for standard insemination. However, over the past three decades, the use of ICSI has increased dramatically. Nowadays, couples doing IVF for other reasons are choosing ICSI, even if the sperm is completely normal. Most IVF clinics are performing ICSI in well over 50% of their cycles.
The main reason for this overuse of ICSI is the fear that the eggs will fail to fertilize with standard insemination. The desire to avoid fertilization failure compels many to choose ICSI to “ensure” fertilization as much as possible. However, the actual probability of fertilization failure with standard insemination is low (5%) when the sperm is normal. Furthermore, ICSI does not guarantee fertilization, and fertilization failure also happens with ICSI (2%).
Importantly, studies on large IVF databases have shown that when the sperm is normal, pregnancy rates are equivalent whether standard insemination or ICSI is done. Proponents of standard insemination argue that standard insemination allows “natural selection” to take place and for the best sperm to declare itself and find the egg. The pendulum also seems to be swinging away from routine use of ICSI because a few studies suggest a very slight increase in the risk of birth defects in babies conceived by ICSI. However, this finding is likely a reflection of the genetics of couples who have to do ICSI, rather than of the technique itself. In clinical practice, ICSI is thought to be safe, which is why it is still used in the majority of cases.
The bottom line is that there are some scenarios in which ICSI should definitely be performed. When there are sperm problems, when couples are doing genetic testing of the embryos (PGS), and when couples have a history of failed fertilization with standard insemination in the past, ICSI is prudent. However, when the sperm is completely normal, standard insemination should be considered. Or, do what many couples do and split the eggs, fertilizing some with standard insemination and some with ICSI. With a split, fertilization failure is avoided as much as possible, and you and your physician can find out if your eggs and sperm can fertilize naturally. Before your IVF cycle, start thinking about how you want your eggs to be fertilized, but also know that your physician is there to help you decide whether to ICSI or not to ICSI!