Conventional IVF and ICSI: understanding the differences

Conventional IVF and ICSI differ in how fertilisation is carried out in the laboratory. ICSI is performed as part of IVF. The choice should address a specific indication, rather than an assumed ranking from less to more effective.

Conventional IVF

After ovarian stimulation and egg collection, prepared sperm are placed with the eggs in the laboratory. Fertilisation occurs without directly injecting a sperm into an egg. This approach may be chosen when the assessment and sperm characteristics support its use.

ICSI: injecting a sperm into an egg

The embryologist selects a sperm and injects it into a mature egg using a micropipette. This is not a random choice. ICSI may be indicated for significant sperm abnormalities, surgically retrieved sperm, or very low or absent fertilisation in a previous conventional IVF cycle.

Should ICSI always be preferred?

No. Without a male factor or a history of fertilisation problems, routine ICSI has not been shown to improve live birth outcomes. Age or low ovarian reserve alone does not justify this choice.

Distinguishing fertilisation failure from not becoming pregnant

Fertilisation failure means that the eggs were not fertilised, or that fewer fertilised than expected. This differs from an embryo transfer that does not result in pregnancy. That outcome does not automatically justify switching to ICSI: the laboratory report and the overall treatment history need to be reviewed.

What happens after fertilisation?

Embryos are monitored in the laboratory. Culture duration and the transfer decision depend on their development and the clinical situation; transfer on day five is not automatic. Embryos may also be stored for a later transfer, depending on the treatment plan and the applicable framework.

What should be discussed before treatment?

Some eggs can be damaged during ICSI manipulation. Certain causes of male infertility are genetic and may require appropriate testing or genetic counselling. These issues should be distinguished from a blanket claim that ICSI itself transmits genetic abnormalities.

An explained decision for your circumstances

The medical and laboratory team explains the proposed method, its purpose, limitations and alternatives. The semen assessment and detailed results of previous attempts are more useful than the name of the technique alone. You can ask what specifically supports the choice in your circumstances.

Conventional IVF and ICSI: understanding the differences