IVF guide
What is ICSI?
ICSI (intracytoplasmic sperm injection) is a laboratory technique used during IVF. A single sperm is injected directly into each mature egg to help fertilization.
How ICSI works
After egg collection, the eggs are cleaned of the surrounding cells so that the embryologist can see whether they are mature. Under a high-magnification microscope, each mature egg is held gently with a fine glass pipette. A single sperm is picked up with an even thinner needle and placed inside the egg.1 The injected eggs are then kept in an incubator.
Conventional IVF and ICSI
In conventional IVF, eggs and prepared sperm are placed together in a culture dish and fertilization happens on its own. In ICSI, the embryologist selects one sperm for each egg. Both methods are followed by the same steps: embryo culture, embryo transfer and, if there are suitable embryos, freezing.3
When ICSI may be used
- Low sperm count, low motility or many abnormally shaped sperm
- Sperm obtained surgically from the testis or epididymis
- Poor or no fertilization in a previous conventional IVF cycle
- Use of previously frozen eggs
- Cycles planned with preimplantation genetic testing
The decision depends on the semen analysis, the history of the couple and the laboratory findings on the day.3
Checking fertilization
About 16 to 18 hours after the injection, the embryologist checks each egg. A normally fertilized egg shows two small circles called pronuclei, one from the egg and one from the sperm.2 Not every injected egg fertilizes, and not every fertilized egg develops into an embryo suitable for transfer.
Things to know
- ICSI can help fertilization when sperm numbers are low, but it cannot improve the quality of the egg.
- A small number of eggs may be damaged during injection.2
- Where a genetic cause of male infertility is suspected, genetic counselling may be recommended before treatment.4
At a glance
- ICSI is part of an IVF cycle, not a separate treatment.
- Only mature eggs can be injected.
- Fertilization is checked the day after the injection.
- The physician and embryologist decide whether ICSI is used.
Frequently asked questions
No. ICSI is a fertilization method used within an IVF cycle. The rest of the cycle, such as stimulation, egg collection and embryo transfer, is the same.
Not necessarily. The physician and embryologist decide according to the sperm parameters, previous treatment and the eggs collected.
No. ICSI only helps fertilization. In Turkey, selecting the sex of an embryo is not permitted.5
References
- Palermo G, Joris H, Devroey P, Van Steirteghem AC. Pregnancies after intracytoplasmic injection of single spermatozoon into an oocyte. The Lancet. 1992;340(8810):17–18.
- ESHRE Special Interest Group of Embryology and Alpha Scientists in Reproductive Medicine. The Vienna consensus: report of an expert meeting on the development of ART laboratory performance indicators. Reproductive BioMedicine Online. 2017;35(5):494–510.
- National Institute for Health and Care Excellence (NICE). Fertility problems: assessment and treatment. NICE guideline NG257. 2026.
- European Association of Urology. EAU Guidelines on Sexual and Reproductive Health. Arnhem: EAU Guidelines Office; 2025.
- Republic of Türkiye Ministry of Health. Regulation on Assisted Reproductive Treatment Practices and Assisted Reproductive Treatment Centres (Üremeye Yardımcı Tedavi Uygulamaları ve Üremeye Yardımcı Tedavi Merkezleri Hakkında Yönetmelik). Official Gazette, 30.09.2014, No. 29135 (as amended).
Related topics
This page gives general information only. It does not replace an examination, and the treatment plan is decided by the physician for each person individually.