In vitro fertilisation (IVF) is one of the most widely used techniques in assisted reproduction, and there are two main ways of carrying it out: conventional IVF and ICSI (intracytoplasmic sperm injection). Although both procedures share common stages — such as ovarian stimulation, follicular aspiration and embryo transfer — they differ mainly in the way the egg is fertilised.
Convencional IVF
In this method, the retrieved eggs are placed in a laboratory dish together with a specific number of sperm. Fertilisation occurs spontaneously: a single sperm penetrates the egg’s membrane on its own. This procedure naturally mimics the fertilisation process and is usually used when the sperm parameters are normal and there are no signs of male infertility.
ICSI (IntraCytoplasmic Sperm Injection)
ICSI is a more precise and controlled technique. It involves selecting a single sperm, which is injected directly into the egg using a micro-needle. It is used particularly in cases of severe male infertility (low sperm count, poor motility or morphology), previous fertilisation failures, or when sperm obtained via testicular biopsy is used.
Main differences:
• Method of fertilization: spontaneous in IVF, assisted by ICSI.
• Semen requirements: IVF requires normal parameters; ICSI can be used with low-quality samples.
• Clinical use: IVF is used for couples without severe male factors; ICSI is reserved for cases involving sperm-related complications.
Both techniques are effective, and the choice between them will depend on an individual medical assessment of each case.
Daniel García
Embryologist
Differences between conventional IVF and ICSI
