Difference Between IVF and ICSI

Welcome to our comprehensive guide on the difference between IVF (in-vitro fertilisation) and ICSI (intracytoplasmic sperm injection). Both are widely used to address infertility, yet they differ in how the egg and sperm meet. Whether you’re considering fertility treatments for the first time or looking to learn more about your options, this overview will help you make an informed decision that fits your unique circumstances.

Understanding IVF Treatment

In IVF, a woman’s egg is retrieved from her ovaries and combined with sperm in a laboratory setting. Once fertilisation occurs, the resulting embryo is then transferred back into the womb to develop. This type of fertility treatment can involve the woman’s own eggs and her partner’s sperm, or use donor eggs or donor sperm if needed. In some cases of male infertility—such as low sperm count—a procedure called ICSI may be recommended, where a single sperm is carefully injected directly into an egg.

The IVF Process Step by Step

Below is a step-by-step overview of an IVF cycle. Protocols may vary depending on individual infertility diagnoses and your clinic’s approach, so it is always best to consult a qualified embryologist or fertility specialist.

Starting Your IVF Cycle: Day 1 of menstruation typically marks the beginning of an IVF cycle.Your clinic will plan hormone schedules and scans to optimize reproductive outcomes.
Ovarian Stimulation: Hormonal medications (often injections) promote multiple egg follicles instead of just one. The goal is to stimulate the ovaries to produce several mature eggs, increasing success rates.
Egg Retrieval: A minor procedure under sedation or anesthesia uses ultrasound guidance to retrieve eggs. The number of eggs collected varies by factors like age, sperm count, and overall health.
Sperm Preparation: A fresh or frozen sperm sample is evaluated by an embryologist for the healthiest cells. Donor sperm may be used if needed; however, severe male infertility often involves more advanced methods covered separately.
Lab Fertilisation: In standard IVF, eggs and sperm are placed together in a dish to naturally fertilise. The fertilised eggs are checked for normal development; those that progress become embryos.
Embryo Development: Early-stage embryos grow in an incubator, often reaching the blastocyst stage (~5 days). Not all embryos will thrive; abnormality or genetic issues can affect development.
Embryo Transfer: A viable embryo is transferred to the womb via a thin catheter.
Pregnancy Test: Roughly two weeks later, a blood test confirms whether implantation occurred. If not successful, additional cycles or alternative treatments may be considered to address infertility challenges or low sperm count.

For a more detailed overview, please refer to our page on the IVF process.

Exploring ICSI Treatment

ICSI is a specialised fertility treatment designed to overcome certain types of male infertility, such as low sperm count or poor motility. Unlike standard IVF, ICSI injects a single sperm directly into each egg, bypassing barriers that can prevent natural fertilisation. Today, it is widely used by fertility clinics worldwide to boost success rates for couples who might otherwise struggle to conceive.

The ICSI Process Step by Step

Starting Your ICSI Cycle: Similar to an IVF cycle, hormones stimulate multiple eggs to mature. Your clinic will track follicle growth with scans and blood tests.
Egg Retrieval: Under sedation, a specialist uses ultrasound guidance to retrieve eggs. The number of eggs collected varies based on individual factors like ovarian response.
Sperm Preparation: An embryologist examines fresh or frozen sperm and selects the healthiest cells. Even with a very low sperm count, a viable sperm can often be found for ICSI treatment.
Sperm Injection: In a controlled lab setting, a single sperm is carefully injected into each egg. This direct sperm injection helps fertilise eggs that might not respond to standard methods.
Embryo Development: Fertilised eggs become embryos and are placed in an incubator. Not all will develop normally; abnormality or genetic issues can limit growth. Those that reach the blastocyst stage (around Day 5) often have a better chance of implanting.
Embryo Transfer: A viable embryo is transferred into the womb using a thin catheter. Most individuals resume normal activities shortly afterward.
Pregnancy Test: About two weeks later, a blood test checks for pregnancy (hCG levels). If unsuccessful, additional fertility treatment options may be discussed, including more IVF and ICSI cycles or other reproductive therapies.

For a more detailed overview, please refer to our page for ICSI.

The Difference Between IVF and ICSI

While IVF and ICSI both involve ovarian stimulation, egg retrieval, and embryo transfer. The key difference is how fertilisation takes place. In standard IVF, eggs and sperm are placed together in a dish to fertilise naturally, making it suitable for couples without severe male infertility. By contrast, ICSI involves the precise injection of a single sperm into each egg, which can help overcome barriers in cases of low sperm count or poor motility. Choosing between IVF and ICSI often depends on sperm parameters, medical history, and any prior fertilisation challenges. A fertility specialist can help determine which method best aligns with your specific needs.

IVF and ICSI Success Rates

Empirical data show that IVF and ICSI can yield broadly similar live birth rates under many circumstances, especially when male infertility is not the principal factor (Balli et al., 2022). Below is a concise overview of success-rate findings from two large-scale publications:

A national observational study covering 319,105 IVF/ICSI cycles in the UK found live birth rates around 25%–27% per cycle from 2012 to 2016 (Bahadur et al., 2020).
Although the study grouped IVF and ICSI together, its large-scale data provide a useful benchmark for understanding average success rates in routine clinical practice.
A 2022 review highlights that in couples without severe male-factor issues, ICSI does not necessarily improve live birth rates compared to conventional IVF.
ICSI has become more prevalent worldwide, yet this shift has not always translated into better outcomes in non-male-factor cases.

Potential Risks and Abnormalities

Both IVF and ICSI involve hormone stimulation, egg retrieval, and embryo transfer. While these procedures are generally safe, research shows there are some increased risks and abnormalities to consider, many of which are linked to underlying infertility factors, maternal age, or multiple pregnancies rather than the laboratory methods themselves (Zollner & Dietl, 2013).

Risk/Complication	General Risk	IVF	ICSI
Ovarian Hyperstimulation (OHSS)	Can occur in both IVF and ICSI when fertility drugs overstimulate the ovaries. Usually associated with exogenous gonadotropins. Mild to moderate cases are more common; severe OHSS is rare (≈0.2% of cycles)	Tends to be more discussed in standard IVF protocols, especially those with high-dose stimulation. Some protocols (e.g., mild IVF) reduce this risk	The same hormonal stimulation protocols can be used, so the risk is not significantly different from IVF.
Multiple Pregnancy	Multiple Pregnancy Higher rate than in spontaneous conception if multiple embryos are transferred. Can lead to preterm birth, low birth weight, or other maternal complications (e.g., pre-eclampsia). Elective single embryo transfer (eSET) helps reduce this risk.	Traditionally, IVF can involve 2–3 embryos per transfer (depending on regulations), thus potentially leading to more twins or triplets- Trend towards single embryo transfer (SET) reduces multiples.	ICSI also often involves transferring more than one embryo, unless eSET is specifically chosen. The method of fertilisation (IVF vs. ICSI) matters less than the number of embryos transferred.
Pregnancy Complications (e.g., pre-eclampsia, hypertension)	Slightly increased risk in pregnancies conceived through ART overall. Often linked to older maternal age, existing health conditions, or subfertility factors.	No major procedure-specific difference; risk is more tied to multiple pregnancy or maternal factors.	Similarly, no unique risk attributed solely to sperm injection; underlying male-factor infertility or maternal issues play a bigger role.
Low Birth Weight & Preterm Delivery	Some studies show a modestly higher rate in singletons conceived via ART compared to spontaneous conceptions. Multiple pregnancies significantly increase the risk of premature birth and low birth weight.	When 2+ embryos are transferred, the odds of twins or triplets rise, boosting preterm birth risk.	Same dynamic applies if multiple embryos are transferred; direct sperm injection does not independently raise preterm birth risk unless multiple embryos implant.
Congenital Anomalies	Slightly elevated risk overall compared to spontaneously conceived babies, but absolute increase remains small. Often associated with parental factors (e.g., advanced age, genetics).	Data generally do not show a significant difference in anomalies solely from standard IVF.	Some large-scale studies suggest a slightly higher risk of certain chromosomal or imprinting abnormalities in ICSI-conceived children, especially when severe male-factor infertility is present. However, many studies find no conclusive difference once parental risk is accounted for
Imprinting Defects (e.g., Beckwith-Wiedemann, Angelman)	Very rare overall, yet appear marginally more often in ART vs. natural conception. Unclear if it’s due to subfertility itself or lab procedures (culture media, ICSI technique, etc.).	No strong evidence of IVF alone significantly elevating imprinting disorders, though it can’t be fully ruled out.	Some case reports and small studies note a slightly increased incidence in ICSI pregnancies; paternal genetic factors and sperm selection may be a contributing factor.
Male-Factor Genetic Considerations (sperm-linked anomalies, etc.)	If the father has underlying genetic issues, there is a small risk of passing these on, regardless of IVF or ICSI.	Not specifically an IVF-only concern, though male factor might be less of an issue if the sperm parameters are normal.	Particularly relevant when severe male infertility is present (low sperm count, poor motility). Injecting a sperm with unrecognized genetic issues may slightly increase risk of chromosomal abnormalities in the offspring.

Keep in mind that many large-scale studies find that most complications are linked to underlying parental factors (e.g., advanced maternal age, sperm abnormalities, or multiple embryo transfers), rather than the IVF or ICSI procedure itself.

IVF or ICSI — Which Should You Choose?

Choosing between IVF and ICSI often depends on the underlying cause of infertility and the specific recommendations of a fertility specialist. Below is a simple reference guide, but note that you should consult a with your healthcare provider.

Condition or Situation	More Likely Approach
Healthy sperm parameters	IVF (standard)
Unexplained infertility	Often start with IVF; ICSI if fertilisation failure occurs
Severe male infertility (low sperm count, poor motility)	ICSI (direct sperm injection)
Previous failed/poor fertilisation in IVF	ICSI
Donor sperm with normal parameters	IVF (standard)
Donor sperm with compromised motility	ICSI

Next Steps on Your Fertility Journey

If you’re ready to explore your treatment options—or simply want a second opinion—our team is here to help. Request a consultation or call us to speak with a dedicated fertility specialist who can guide you toward the best solution for your journey.

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Is ICSI better than IVF?

Not necessarily. ICSI can help in cases of severe male infertility, but for couples without sperm issues, standard IVF is often just as effective. Your fertility specialist can recommend the best method based on your situation.

How much does IVF with ICSI cost?

In the UK, IVF with ICSI typically costs between £5,000 and £8,000 per cycle. Prices vary depending on the clinic and what’s included, so it’s best to ask for a full cost breakdown.

What are the success rates for IVF and ICSI?

On average, live birth rates per cycle for both IVF and ICSI in the UK are around 25%–27%. Success depends mostly on factors like age, egg quality, and underlying fertility issues.

References

Zollner, U., & Dietl, J. (2012). Perinatal risks after IVF and ICSI. Journal of Perinatal Medicine, 41(1), 17–22. https://doi.org/10.1515/jpm-2012-0097

Bahadur G, Homburg R, Bosmans JE, et al. (2020). Observational retrospective study of UK national success, risks and costs for 319,105 IVF/ICSI and 30,669 IUI treatment cycles. BMJ Open 2020;10:e034566. doi:10.1136/ bmjopen-2019-034566

Balli, M., Cecchele, A., Pisaturo, V., Makieva, S., Carullo, G., Somigliana, E., Paffoni, A., & Vigano, P. (2022). Opportunities and Limits of Conventional IVF versus ICSI: It Is Time to Come off the Fence. Journal of Clinical Medicine, 11(19), 5722. https://doi.org/10.3390/jcm11195722

Devroey, P. (2004). A review of ten years experience of ICSI. Human Reproduction Update, 10(1), 19–28. https://doi.org/10.1093/humupd/dmh004

The Difference Between IVF and ICSI – Two Popular Methods Within Assisted Reproductive Technology