ICSI vs IVF: key differences explained

Facing fertility challenges can be an emotional and uncertain journey, and it’s completely normal to feel a little overwhelmed. With so many fertility treatments available, knowing where to start can be confusing.

Intracytoplasmic sperm injection (ICSI) and in vitro fertilisation (IVF) are two of the most popular fertility treatments – but what’s the difference between them, and how can you know which is right for you?

In this blog post, we’ll break down exactly what ICSI and IVF involve, highlight their key differences and guide you through the basics to help you understand which treatment may suit your needs. Discover everything you need to know about ICSI vs IVF with Bourn Hall Fertility Clinic. 

What is IVF?

IVF is a fertility treatment where an egg is fertilised with sperm outside the body, in a laboratory. This is done by placing sperm and egg together in a dish, allowing fertilisation to happen on its own over the next 18 hours or so.

Once fertilisation occurs, the embryo is carefully placed back into your womb. Sometimes, more than one egg is fertilised during the process. Any additional embryos can be frozen and stored for future treatments such as FET.

What is ICSI?

ICSI is a fertilisation technique where sperm is given a helping hand to reach and fertilise an egg in a laboratory. In this process, a single sperm is directly injected into the egg’s cytoplasm (the jelly-like substance surrounding the centre of the egg) to encourage fertilisation.

Once fertilised, the egg is placed back into the womb, where it has the chance to implant and lead to pregnancy. If there are extra embryos (fertilised eggs), they can be frozen for future use, giving you more opportunities for fertility treatments like a frozen embryo transfer (FET).

ICSI can also be included as part of an IVF cycle or package. This means you’ll follow the IVF process up to the point of fertilisation, but instead of standard IVF fertilisation, the ICSI method will be carried out instead.

Is ICSI or IVF right for me?

Although both ICSI and IVF can lead to a successful pregnancy, one approach may be better suited to your needs than the other. 

IVF might be recommended if: 

• You have unexplained fertility issues
• Your fallopian tubes, which transport eggs from your ovaries to your uterus, are blocked or not functioning as they should
• Other treatments, like intrauterine insemination (IUI), have not been successful

Alternatively, ICSI may be more suitable if: 

• You have a low sperm count
• Your sperm motility (movement) is reduced
• A high proportion of your sperm are abnormally shaped 
• Previous IVF cycles had resulted in not creating any embryos or they had created fewer than expected numbers of embryos
• You’re using donated eggs or sperm 
• Semen analysis testing suggests that fertilisation may be difficult 

The decision of which treatment is right for you will be made together with your fertility specialist. They’ll provide you with personalised advice based on your needs and health, giving you the best opportunity of becoming a parent.

The key differences between ICSI and IVF

While ICSI and IVF seem similar, they do have some key differences. Let’s take a look at the main differences between the two. 

Difference	ICSI	IVF
Fertilisation method	A single sperm is directly injected into the egg using a fine needle.	Sperm and eggs are placed together in a petri dish to fertilise naturally.
Sperm assistance	Direct injection of sperm into the egg gives the sperm a helping hand.	No direct assistance; sperm must swim toward and fertilise the egg on their own.
Suitability	Ideal for cases where sperm motility is low or sperm count is low.	Suitable for cases of unexplained infertility or when there are no sperm motility or count issues.
Approach	More targeted – sperm is specifically selected and injected.	Less targeted – relies on natural fertilisation.
Success rate	Success is potentially higher when sperm motility or count is an issue.	Success depends on the sperm’s natural ability to fertilise the egg, as well as a range of other factors.

Although ICSI and IVF have some differences, both are well-established methods that can help you start or grow your family. With the support of your fertility specialist, you can explore your options and decide which is right for you. 

Which treatment is more successful, ICSI or IVF?

Both ICSI and IVF are proven fertility treatments, and success often depends on your circumstances rather than the method alone.

For instance, if there are no issues with sperm quality, IVF may be a suitable first option. However, if you or your partner has a low sperm count or poor sperm motility, IVF may not lead to fertilisation, and that’s where ICSI can make a difference. By directly injecting a healthy sperm into the egg, ICSI can help overcome certain fertility challenges and improve the chances of successful fertilisation.

Learn more about our ICSI and IVF success rates.  

Potential risks and considerations of ICSI and IVF

While both ICSI and IVF are generally considered safe, like any medical procedure, they do carry some potential risks – though it’s worth bearing in mind that the chances of these risks occurring are small. Being fully aware of these risks can help you feel more informed and prepared as you consider your fertility treatment options. 

However, risks are typically identified early through monitoring and can be managed with medical care. Your fertility team will guide you through what to watch for and ensure you receive prompt care if needed. 

Possible risks of ICSI include: 

• Damage to the egg – due to the injection process, there is a small risk that the egg could become damaged. This is a rare complication, and our embryologists take great care to handle each egg with precision and expertise.
  
• Ectopic pregnancy – in rare cases, the embryo may implant outside the womb, most commonly in one of the fallopian tubes. Ectopic pregnancy can become a medical emergency if left untreated and your fallopian tube ruptures due to the growing embryo
  
• Ovarian hyperstimulation syndrome (OHSS) – to increase the number of mature eggs your body produces, you’ll be given medication to stimulate your ovaries before ICSI treatment. In some women, this can cause the ovaries to become enlarged and painful

Potential risks of IVF include: 

• OHSS – the medications used to stimulate egg production in IVF may lead to OHSS. However, our fertility team will monitor you closely to detect any symptoms as early as possible
  
• Multiple births – if more than one embryo is transferred to the womb, there’s a chance more than one may implant, which can lead to a multiple pregnancy. While this may be a positive outcome for some, multiple births do carry additional risks for parents and babies, which your specialist will discuss with you
  
• Ectopic pregnancy – as with ICSI, there is a small risk of the embryo implanting outside the womb

Health of children after IVF or ICSI

The health of the children born after IVF and ICSI is a very important outcome that we monitor. We always aim to receive feedback from the parents about their pregnancies and babies after successful treatment and our regulations also require this.

The research indicates that the risk of serious abnormalities is overall low with both IVF and ICSI. Some older research suggested certain, non-life-threatening abnormalities of the urinary or genital systems were slightly more common with ICSI.

However, we are also aware that, if there is some increased risk with IVF or ICSI, it may be because the people who need fertility treatment may be more at risk (compared to the ones who don’t need treatment), rather that a risk that is caused by the IVF or ICSI techniques. There has been research that has shown that even the babies of couples who have achieved natural conception with some delay could be at slightly higher health risk compared to those who have fallen pregnant without delays.

Based on the above evidence, we believe that it is prudent to use the technique that is the least invasive, but still effective, and we’re prepared to change the method in a future cycle if the original technique has not delivered. We ensure our patients are well informed about these choices so that they can make the right decisions for their needs.

Explore ICSI and IVF with Bourn Hall Fertility Clinic

If you’re considering ICSI or IVF, Bourn Hall Fertility Clinic can help. Our expert team offers comprehensive consultations, during which we discuss your unique goals, needs and overall health, helping you make an informed decision about the treatment that’s right for you. 

Contact our team today to start your fertility treatment journey.