ICSI vs. IVF: What Is the Difference?

9 min
Updated May 31st, 2024

Table of contents

For couples having difficulty conceiving naturally, assisted reproductive technologies like ICSI and IVF offer a ray of hope. While both treatments aim to help you get pregnant, they differ in their approach and suitability for different fertility issues. Understanding the nuances between ICSI and IVF can help you make an informed decision about your treatment options. Here, we’ll look at each of these common fertility treatments in more detail, their benefits and key differences.

What is ICSI treatment?

Intracytoplasmic Sperm Injection (ICSI) is an advanced form of in vitro fertilisation (IVF) that involves injecting a single sperm directly into a mature egg for fertilisation. This highly specialised procedure is called micro-manipulation. It involves the use of a microscope on a specialised deck using a glass catheter 1/7 the size of a human hair to inject a single sperm into the egg. 

Typically it’s recommended for couples facing male infertility issues, such as low sperm count, poor sperm motility, or abnormal sperm morphology. ICSI can also be beneficial in cases where previous IVF cycles have been unsuccessful due to fertilisation problems or when the male partner has a genetic disorder that could affect sperm quality. It may also be advised if you’re using frozen eggs or frozen sperm. The development stage of the embryos is the same as with IVF, with the embryos kept in the lab to develop before replacement or freezing. 

What is IVF treatment? 

In vitro fertilisation (IVF) is a widely recognised assisted reproductive technology that involves fertilising eggs with sperm outside the body in a controlled lab environment. The process begins with ovarian stimulation to produce multiple eggs, followed by egg retrieval and fertilisation. Once fertilised, the resulting embryos are cultured and monitored for several days before the most viable embryo(s) are transferred into the woman’s uterus. 

IVF is often recommended for couples struggling with various fertility issues, including blocked fallopian tubes, endometriosis, or unexplained infertility. 

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What are the benefits of ICSI?

Due to its adaptability across various male fertility challenges and relatively reliable outcomes, ICSI has emerged as the most widely adopted assisted reproductive technology procedure globally. ICSI offers several benefits for couples facing male-factor infertility. However, it is worth noting that studies have shown no improvements in pregnancy rates when ICSI is used for non-male factor fertility issues. Here are the key benefits of ICSI and why you might consider it as a viable option:

  • Increased fertilisation rates: By directly injecting a single sperm into the egg, ICSI maximises the chances of fertilisation, even with poor sperm quality or low sperm count. ICSI navigates any potential barriers that could hinder natural fertilisation. This targeted approach ensures that fertilisation has the highest possible chance of occurring, regardless of the quality or quantity of sperm available.
  • Genetic testing opportunities: As in IVF, ICSI allows for the selection of genetically normal embryos through preimplantation genetic testing (PGT), reducing the risk of passing on inherited disorders. This genetic screening capability provides couples with valuable information and peace of mind, increasing the chances of a healthy pregnancy and birth.
  • Overcoming fertilisation barriers: In some cases, even with conventional IVF, the sperm and egg may face compatibility issues or biological barriers that prevent them from naturally binding and fusing together. ICSI overcomes these obstacles by directly injecting the sperm into the egg. This ability to bypass fertilisation obstacles has made ICSI a game-changer for couples facing male factor infertility or other fertility challenges that may interfere with natural fertilisation.

What are the benefits of IVF?

IVF has made major advancements in recent years, with successful outcomes for nearly 50% of cases in which the woman is younger than 35. IVF provides numerous benefits for couples experiencing various fertility challenges:

  • Increased chances of conception: By directly transferring embryos into the uterus, IVF offers a potential solution to issues such as blocked or damaged fallopian tubes, ovulation problems or other factors that may hinder natural conception. 
  • Genetic screening: Like ICSI, IVF allows for preimplantation genetic testing (PGT). This advanced technique allows for the screening and selection of genetically healthy embryos, reducing the risk of passing on inherited genetic disorders or chromosomal abnormalities to the child.
  • Suitable for various fertility issues: IVF is a versatile treatment option that can address a wide range of fertility problems affecting both men and women. It can help overcome issues such as ovulation disorders, endometriosis, uterine factor infertility, and male factor infertility, including low sperm count or poor sperm motility.

What are the main differences between IVF and ICSI?

Whilst there are similarities between treatments such as providing the opportunity for fertility preservation, there are also differences. ICSI is essentially IVF but with specific help to achieve fertilisation using the direct injection of sperm into the cytoplasm of the egg. This additional step results in some significant differences between the two treatments:

The cost

ICSI is more expensive than traditional IVF due to the specialised equipment and expertise required for the procedure. The cost can vary depending on the fertility clinic and location, but ICSI typically adds an additional expense on top of the IVF cycle. Self-funded treatment will be approximately 25% higher for ICSI compared to IVF. For reference, in a recent study, the average cost of NHS-funded fresh IVF and ICSI cycles in Scotland were calculated at £3,247 and £3,473 respectively. Frozen cycles averaged £938. 

The chance of success

Both IVF and ICSI have varying success rates depending on factors such as the woman’s age, the cause of infertility, and the clinic’s experience. However, ICSI may offer higher fertilisation rates for couples with severe male factor infertility. 

Studies cite conventional IVF as a viable option for couples seeking fertility treatment and should only be avoided in cases of severe male factor infertility or the presence of anti-sperm antibodies, in which case ICSI may be more effective. 

Studies also show that women undergoing IVF have an inadequate understanding of their chance of live birth with IVF, and that most overestimate their chances, so it is important to do your research, understand the reasons for IVF failure and note that the success rates can differ depending on age, fresh vs frozen embryo transfer and various other factors. Chances of success can be improved with the right preparation, a healthy diet and the use of research-backed fertility supplements. Always discuss your individual chances with your fertility specialist.

The process

In conventional IVF and in ICSI, the woman is stimulated with drugs to achieve the development of many follicles containing eggs. This requires careful monitoring, daily injections and is an intense process. In IVF, once the eggs have been retrieved, they are combined with a prepared sample of the partner’s (or donor’s) sperm and cultured in an incubated, carefully controlled environment. Thousands of sperm cells are introduced to each egg, and sperm fertilise the eggs through the sperm’s motility and ability to penetrate the egg’s outer layer. When it comes to ICSI, however, the fertilisation process is more controlled and precise. Each mature egg is held in place under a powerful microscope while a single, healthy sperm cell is carefully selected and immobilised. Using specialised equipment, the selected sperm cell is then injected directly into the egg, removing the need for natural sperm penetration. This additional step in the ICSI process is what sets it apart from traditional IVF. The IVF process can take several weeks, while ICSI adds an additional step to the procedure.

IVF or ICSI: Which treatment is best for you?

When considering IVF or ICSI, it’s important to balance the potential benefits, potential harm, and associated costs to provide the best value for each individual case. Your specialist will be of great help here. The decision to pursue IVF or ICSI depends on various factors, including the cause of infertility, previous treatment outcomes, and personal preferences. For the majority of people with no issues with male factor infertility, ICSI will not increase chances of pregnancy but will increase the cost. 

However, ICSI is often recommended for couples with extremely low sperm count, poor sperm morphology (abnormal shape), poor sperm motility (impaired movement) or those who have experienced fertilisation issues during previous IVF cycles. Whereas, for couples with unexplained infertility or female factor infertility, traditional IVF may be the preferred approach, as ICSI may not offer clear advantages.

ICSI is also recommended when sperm needs to be surgically extracted from the testicles or epididymis.

There are risks and side effects that should also be considered when researching fertility treatments. For example, there are concerns that ICSI may increase the chances of some developmental defects in children. Although the risk is considered minimal, couples may want to discuss this and consider this factor carefully before proceeding.

Both IVF and ICSI are effective assisted reproductive technologies that offer hope to couples dealing with infertility. While IVF is a more generalised approach, ICSI is specifically designed to address male-factor infertility issues. Understanding the differences between these treatments can help couples make an informed decision, in consultation with their fertility specialist, to choose the most appropriate option for their unique situation.


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