IVF or ICSI: What's the Difference and Which Applies to You?

IVF and ICSI differ at one step. In IVF, eggs and prepared sperm are placed together and fertilization is left to happen. In ICSI, an embryologist selects a single sperm and injects it directly into each egg. Everything before and after, the stimulation, the egg collection, the culture of embryos and the transfer, is the same. ICSI exists to solve a sperm problem. Where there is one, it is the right choice. Where there is not, an American Society for Reproductive Medicine committee opinion finds that using ICSI routinely does not improve live birth rates, and it costs more.

What is the difference between IVF and ICSI?

	IVF	ICSI
How fertilization happens	Sperm and eggs placed together; fertilization occurs on its own	One sperm injected directly into each egg
Sperm required	Enough motile, normally formed sperm to fertilize	Very few, including surgically retrieved sperm
Main use	Where sperm parameters are adequate	Male factor infertility, or previous fertilization failure
Cost	Lower	Higher

Everything else about the two cycles is identical from the patient's point of view. The difference happens in the laboratory on one day.

When is IVF the right choice?

IVF is generally used where the sperm is adequate to fertilize an egg and the obstacle lies elsewhere: blocked fallopian tubes, ovulation problems that have not responded to simpler treatment, unexplained infertility, or where IUI has not succeeded.

When is ICSI the right choice?

• A very low sperm count, poor motility, or a high proportion of abnormally formed sperm.
• Sperm retrieved surgically through TESA, PESA or TESE, where the numbers are too small for conventional insemination.
• Previous fertilization failure in a conventional IVF cycle.
• Frozen sperm where post-thaw quality is limited.

Note what these have in common: they are all situations where sperm cannot reliably fertilize an egg unaided. That is what ICSI is for.

Which has better success rates?

This is where the honest answer differs from the usual one. ICSI achieves better fertilization where there is a sperm problem, because it removes the barrier. It does not produce better outcomes in general. The American Society for Reproductive Medicine committee opinion concludes that in the absence of male factor infertility or prior fertilization failure, routine ICSI does not improve live birth rates.

What actually drives success in both is the woman's age and the underlying diagnosis. If you are offered ICSI and there is no male factor in your case, ask what it is expected to achieve and what it adds to the cost. Our IVF success rates page covers how to read published figures, and any figure should state its year, the number of cycles, the age group, and whether it is per cycle or per transfer and clinical pregnancy or live birth.

What happens before either treatment?

Both start with assessment of both partners: hormone testing, a semen analysis, imaging, and a review of medical, surgical and pregnancy history. That assessment is what determines which method applies, which is why it comes before the choice rather than after it.

We at Millennium IVF Clinic offer both IVF and ICSI and will explain which applies to your results and why. You can arrange a consultation with our team. Our article on what to know before undergoing ICSI goes into more detail on that method.

Frequently asked questions

Is ICSI better than IVF?

Only where there is a male factor or previous fertilization failure. Otherwise the ASRM committee opinion finds no improvement in live birth rates from using it routinely.

Is ICSI more expensive?

Yes. Our costs page sets out package pricing, from around 250,000 to 350,000 THB per cycle depending on the plan and what is included. Ask us for the ICSI difference in writing so you can weigh it against the reason it is being recommended.

Can we switch from IVF to ICSI during a cycle?

In some circumstances a laboratory may use ICSI on some or all eggs based on what is seen on the day. Ask us in advance how that decision is made and whether it affects the cost.

Does ICSI carry extra risks?

ICSI involves an additional manipulation of the egg. Discuss the specific risks with your specialist as part of consenting to treatment.