Intracytoplasmic Sperm Injection (ICSI)

Reviewed by Ashley Wong, MS, Clinical EmbryologistCheckmark | Last updated: April 17, 2020

What Does Intracytoplasmic Sperm Injection (ICSI) Mean?

Intracytoplasmic sperm injection (ICSI) is a method of fertilization where a single sperm is injected directly into an egg as part of an in vitro fertilization (IVF) procedure.

Very few viable sperm are required for this process, making conception possible even with severe male infertility issues.

FertilitySmarts Explains Intracytoplasmic Sperm Injection (ICSI)

An IVF cycle with ICSI is the same treatment with the only difference being that rather than mixing the sperm and egg and leaving them to fertilize, an embryologist injects a single sperm into an egg.

How is ICSI performed?

The procedure involves :

  • The extraction of a mature egg (through ovarian stimulation and egg retrieval.)
  • That is then manually fertilized in a lab ideally with a single motile (movement) and morphologically (shape) normal sperm that is inserted into the cytoplasm of an egg with a hollow needle.
  • Any resulting embryos can then be cultured and possibly be transferred into the recipient's uterus or frozen for a transfer at a later date.

Who is ICSI for?

ICSI is most frequently used to address male infertility factors that impact the quality or volume of sperm or the ability of sperm to penetrate an egg. These include:

  • A low sperm count
  • When sperm have abnormal morphology (size and shape)
  • When sperm have limited motility (movement)
  • When sperm are surgically removed from the epididymis (MESE) or testicles (MicroTESE)
  • When there are high levels of antibodies in the semen
  • When there is a high level of sperm DNA fragmentation
  • When working with a low yield of eggs retrieved to maximize the potential number of fertilized eggs
  • When previous eggs extracted for IVF failed to fertilize using conventional insemination when sperm and egg are mixed together externally
  • When embryos are planned to be screened for preimplantation genetic testing (PGT)

Intracytoplasmic morphological sperm injection (IMSI) is a modification of ICSI that allows an embryologist to better assess sperm morphology.


Sperm Injection

Share this Term

Related Terms

Term Sources

FertilitySmarts uses high-quality sources to support the facts within our content including peer-reviewed studies, academic research institutions, professional organizations, and governmental organizations.

Related Reading


TreatmentAssisted Reproductive Technology (ART)PregnancyIn Vitro Fertilization (IVF)

Trending Articles

Go back to top