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Does Intracytoplasmic Sperm Injection (ICSI) Boost IVF Odds?

The short answer — sometimes. Specifically, if you’re struggling with male infertility, an intracytoplasmic sperm injection could boost fertilization rates.


Intracytoplasmic sperm injection


As anyone on the path to parenthood knows, there are many factors that play into fertility, a healthy pregnancy, and a successful delivery. For individuals or couples undergoing IVF, one of the choices you may be faced with is using traditional In Vitro Fertilization (IVF) versus intracytoplasmic sperm injection (ICSI).


Who can benefit from intracytoplasmic sperm injection (ICSI)?


ICSI is most often recommended for individuals or couples with male factor infertility. Additionally, if you’re using frozen eggs, ICSI will be used to help the sperm penetrate the egg’s outer protective shells, which can harden while frozen.


You may benefit from ICSI if you or your partner:

  • Are experiencing male infertility

  • Have low sperm counts

  • Are struggling with poor sperm motility

  • Have unexplained infertility

  • Are using frozen eggs

  • Are using in vitro mature eggs

  • Have a history of unsuccessful in vitro fertilization attempts


What is the ICSI IVF process?


Intracytoplasmic sperm injection is a part of the IVF process. Specifically, it is an alternative to the traditional fertilization method in the IVF process.


Traditional IVF vs. ICSI

In typical IVF, the egg donor or intended mother is given fertility medications to stimulate the production of multiple eggs, then to prompt ovulation. During ovulation, the mature eggs are collected in a process called egg retrieval and carefully stored in a lab for fertilization.


With traditional IVF, fertility specialists will place the egg in a petri dish and surround it with sperm. This method is considered a more natural approach to fertilization, as it allows the sperm to self select, in a sense. The fertilized egg is then inserted back into the uterus in a process called the embryo transfer.


Learn more about In Vitro Fertilization


ICSI differs in its approach to fertilizing the egg. Rather than surrounding the egg with hundreds of sperm and letting one fertilize the egg naturally, a single sperm is directly injected into the egg. In this way, ICSI bypasses the potential factors that could be preventing the sperm from fertilizing the egg, such as difficulty penetrating the egg’s outer layers.


Why does ICSI help with male factor infertility?


There are many factors that can interfere with fertilization, whether you’re using a more natural process like intrauterine insemination (IUI) or IVF. First, let’s cover what fertilization actually is.


Fertilization is often used to refer to the entire process of creating a fertilized egg, from ovulation through successful implantation. However, fertilization specifically refers to the stage where the sperm penetrates the egg's surface and genetic material is shared between the egg and sperm to result in a zygote, or fertilized egg.


A quick review of the fertilization process

In the natural course of things, given the right timing and conditions, the journey to fertilization begins with millions of sperm. Of these, only a few hundred will reach the egg in the fallopian tubes. The egg has two distinct outer layers: the corona radiata and the zona pellucida. Only a fraction of the sperm will make it past the corona radiata to reach the zona pellucida.


The sperm that make it to the zona pellucida then attach to sperm receptors, which prompt the release of digestive enzymes. These enzymes help the sperm break down the zona pellucida so they can penetrate the shell and reach the egg cell. The first sperm that breaks through the zona pellucida and touches the egg membrane will be the sperm that fertilizes the egg.


The single sperm then attaches the egg cell membrane, and within a few minutes, the outer membranes fuse together and the egg pulls the sperm inside. From there, the genetic material from the sperm merges with that of the egg to create your child’s unique genetic identity.


How ICSI aids the process of fertilization

There are many things that can break down in the process of fertilization.

  • Low sperm count can make it so not enough sperm survive the harrowing journey to reach the egg and penetrate its protective shell.

  • Poor sperm motility can mean the sperm don’t move quickly or efficiently towards the egg, making fertilization difficult

  • Sperm is unable to attach to sperm receptors on zona pellucida and penetrate shell


Whatever the issue, ICSI helps easily facilitate this step. With ICSI, a single sperm is injected directly into the egg where it can begin sharing genetic material. In this way, ICSI takes the burden of fertilization off of the sperm.


ICSI success rates


The American Society for Reproductive Medicine (ASRM) reports that ICSI is a safe and effective fertility treatment that can improve the chances of fertilization for those with male factor infertility or poor fertilization in past IVF cycles.


According to the ASRM, ICSI successfully fertilizes 50-80% of eggs. That being said, there are a few things that can prevent ICSI fertilization from succeeding. If the egg is damaged, the embryo stops growing, or the egg doesn’t evolve into an embryo, fertilization may not occur. [1]


The U.S. Center for Disease Control (CDC) National ART Surveillance System found the following of ICSI fertility treatments. [2]


For those with diagnosed male infertility:

  • The odds of “cycle cancellation” (failed fertilization) were decreased when ICSI was used compared traditional IVF

  • ICSI increased the odds of successful fertilization when male infertility

  • Rates of pregnancy, live births, and miscarriage were not different between traditional IVF and ICSI

  • ICSI is associated with higher rates of multiple births than conventional IVF

  • ICSI is associated with reduced rates of successful implantation


For those without diagnosed male infertility:

  • The odds of “cycle cancellation” (failed fertilization) are fairly similar to traditional IVF

  • ICSI increased the odds of successful fertilization when male infertility

  • ICSI is associated with lower rates of successful implantation, pregnancy, live birth, and multiple live births than traditional IVF


The pros and cons of intracytoplasmic sperm injections


There is ample research to support that ICSI facilitates improved rates of fertilization for those with diagnosed male factor infertility. However, there is less research to support its benefits for those with other fertility issues.


Regarding birth defects, ICSI’s risks are similar to those of IVF, which sit just above defect rates of natural birth of 1.5-3%. [1, 2]


Additionally, findings from small studies suggest that ICSI may be linked with an increased risk in under 1% of ICSI children including: chromosomal abnormalities, hypospadias, autism, Beckwith-Wiedemann syndrome, Angelman syndrome, and male infertility in adulthood. [1, 2]


Experts in fertility have posited that these side effects may not be due to the ICSI procedure at all, but rather to the pre-existing infertility of the sperm, which would otherwise not have fertilized the egg on its own.


Ultimately though, it’s important to remember that these effects have only been found in small studies, and in less than 1% of the many children born from ICSI IVF. In fact, estimates suggest that roughly half a million children each year are brought into the world using ICSI IVF. [3]



So, is ICSI right for you?


If you’re struggling with male factor infertility, are using frozen eggs, or in vitro mature eggs — ICSI could help you overcome fertilization obstacles to increase your odds of a successful pregnancy. If you’re unsure whether ICSI would benefit you, are committed on your journey to parenthood, and want access to the best fertility experts in the world, send us a message. We’d love to hear from you.

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