IVF vs IUI vs ICSI: what is the difference?

The basic difference

These three terms are often confused because they can come up in the same conversation, but they sit at different points in treatment. IUI is a whole treatment approach in its own right. IVF is a different, more involved treatment approach. ICSI is a specific fertilisation method used inside an IVF cycle, not a separate treatment on its own.

IUI: intrauterine insemination

IUI involves preparing a sperm sample in the lab and inserting it directly into the womb using a thin catheter, timed around ovulation, which may be natural or supported with medication to help time it. Eggs are not removed from the body, and there is no lab fertilisation or embryo stage involved.

• Typically considered when sperm quality is reasonably good and the fallopian tubes are open and functioning.
• Generally a less involved and less costly procedure than IVF, though it is repeated over more cycles in many treatment plans.
• Success rates per cycle are generally lower than IVF, since fewer of the natural steps are assisted.

IVF: in vitro fertilisation

IVF involves ovarian stimulation with medication, egg collection under sedation, fertilising the eggs with sperm in the lab, culturing the resulting embryos, and transferring one embryo (or occasionally more) into the womb. Any suitable extra embryos can usually be frozen for future use.

• Generally considered where IUI has not worked, where tubes are blocked, where egg or sperm quality issues need lab-based help, or for a range of other diagnoses your clinic will discuss.
• A more involved process, both physically and financially, than IUI.

ICSI: a method used within IVF

ICSI is not a separate treatment pathway to IVF, it's a way of achieving fertilisation within an IVF cycle by injecting a single sperm directly into an egg rather than mixing eggs and sperm together in a dish. Every other stage of the cycle, stimulation, collection, culture and transfer, is the same as standard IVF.

Some clinics use ICSI as standard for every case rather than only where there is a sperm-related reason. The HFEA's evidence review suggests ICSI without a male factor indication does not have strong evidence of improving outcomes compared with standard IVF fertilisation in that situation, so ask why it's being suggested for you specifically.

How a clinic decides which to recommend

• Results of semen analysis for the male partner.
• Whether the fallopian tubes are open, usually checked by a specific scan or dye test.
• Age and ovarian reserve test results.
• How long you've been trying to conceive and any results from previous treatment cycles.
• Any other diagnosed causes of infertility, such as endometriosis or unexplained infertility.

Time and cost differences to expect

IUI cycles are generally quicker and less costly per cycle than IVF, but IVF often has a higher chance of success per cycle for many diagnoses, which affects the overall time and cost across a course of treatment. Ask your clinic to talk through the expected number of cycles for each option in your situation.