Intracytoplasmic sperm injection (ICSI) is a laboratory technique in which a single sperm is injected directly into an egg. It was developed for male infertility, but it is now used far more widely. This article explains its recognised indications, what the scientific societies say about its use outside male infertility, and what is known about its risks. The overall course of a cycle is described in our article on in vitro fertilization, and an overview of all techniques is in our article on medically assisted procreation.
What is ICSI and how does it differ from conventional IVF?
ICSI follows the same course as IVF: ovarian stimulation, egg retrieval, fertilization in the laboratory, then embryo transfer. Only the fertilization step differs. In conventional IVF, each egg is placed with a prepared sample of sperm and fertilization happens spontaneously. In ICSI, the eggs are stripped of their surrounding cells and, according to the Revue du Praticien, only mature eggs are injected, each with one sperm.
The technique therefore bypasses the natural competition between sperm. It is a tool for specific situations, not a more advanced version of IVF that suits everyone.
What are the recognised indications?
The French medical literature lists five main indications:
- Severe sperm abnormalities in number, motility or shape (the Agence de la biomédecine mentions these three criteria);
- Azoospermia (no sperm in the ejaculate) when sperm can be retrieved surgically from the testicle or epididymis;
- Previous IVF failure, with no fertilization or very poor fertilization;
- Anti-sperm antibodies (an immunological cause);
- Preimplantation genetic testing, where other sperm attached to the egg could interfere with the test. The ASRM advises limiting ICSI in this setting to cases where extraneous sperm could affect accuracy.
Other situations sometimes cited, such as ejaculation problems or sperm frozen before cancer treatment, do not appear in these lists in the sources consulted and should be discussed individually with a specialist.
Is ICSI useful when the cause is not male?
Some descriptions list low egg numbers or a thick shell around the egg as indications. The evidence does not support this. The American Society for Reproductive Medicine (ASRM) concludes that ICSI for advanced maternal age or for low egg yield does not improve live birth outcomes. In unexplained infertility, it may reduce fertilization failure but has not been shown to increase live births. The main documented benefit is a lower risk of total fertilization failure; in one large trial cited by the ASRM, about 33 patients would need ICSI to prevent one case.
A multicentre study of nearly 5,000 patients presented at the ESHRE congress found no difference in fertilization or live birth rates between ICSI and conventional IVF in non-male infertility, whatever the number of eggs retrieved. This is a conference report that should be read with caution, but it is consistent with the ASRM position.
Is ICSI overused?
Its use is high, and the authors of the ESHRE study found no clinical justification for routine ICSI in non-male infertility. According to the Agence de la biomédecine, ICSI was used in 66.8% of IVF attempts in France in 2023, and in 99% of attempts using donor eggs. The ESHRE press release reports that about 70% of European cycles were ICSI in 2015, with large variation between countries.
The British regulator reminds patients that add-ons to treatment should be questioned: it recommends asking why a procedure is offered, whether it could benefit you specifically, and what evidence supports it. The ASRM also notes that ICSI requires additional laboratory experience, resources and time, which raises complexity and cost without a proven gain when there is no male factor.
What do we know about the risks and results?
ICSI carries the general risks of IVF, such as ovarian hyperstimulation and multiple pregnancy, described in our IVF article. Regarding children, the ASRM states that risks seen in offspring after ICSI are generally attributed to the underlying male factor, and that the safety of ICSI when there is no male factor has not been evaluated. One large cohort found higher odds of birth defects after ICSI (odds ratio 1.57), but it included men with and without normal sperm counts, which limits interpretation. The Revue du Praticien also mentions a slight increase in malformations and chromosomal anomalies after assisted reproduction.
For results, the Agence de la biomédecine reports that in 2023, with the couple’s own gametes, live births followed 18.1% of ICSI attempts and 18.7% of conventional IVF attempts. These groups are not directly comparable because they treat different problems.
What should you ask your doctor?
Before ICSI, consider asking:
- What is the reason for ICSI in our case: a sperm test result, a previous fertilization failure, or another reason?
- Would conventional IVF be an option for us, and why or why not?
- If sperm must be retrieved surgically, how is it done and what are the risks of that procedure?
- What is known about the health of children born after ICSI in our situation?
- What are the chances of success at my age, and when would we review the strategy?
A semen analysis and a full assessment of both partners come first; they guide the choice between IUI, IVF and ICSI.
Further reading at La Rose Clinic
Frequently asked questions
What is the difference between IVF and ICSI?
The steps are the same except for fertilization: in IVF, eggs and sperm are placed together, while in ICSI one sperm is injected into each mature egg.
Is ICSI better than IVF?
Not in general. It is recommended for specific indications such as severe sperm abnormalities; studies in non-male infertility found no improvement in live birth rates.
When is ICSI recommended?
Mainly for severe sperm abnormalities, azoospermia with surgical sperm retrieval, previous IVF failure, anti-sperm antibodies, and some genetic testing cases.
Are children born after ICSI healthy?
Most are, but risks seen in studies are generally linked to the underlying male infertility, and research on non-male factor use is limited. Discuss your situation with your specialist.
References
- Intracytoplasmic sperm injection (ICSI) for non-male factor indications: a committee opinion (asrm.org)
- ICSI has no outcome benefits over conventional IVF in routine non-male infertility cases (eshre.eu)
- Treatment add-ons (hfea.gov.uk)
- Assistance médicale à la procréation : aspects biologiques, médicaux et éthiques (larevuedupraticien.fr)
- L’assistance médicale à la procréation (guide) (agence-biomedecine.fr)
- Rapport médical et scientifique : AMP 2023 (rams.agence-biomedecine.fr)
This article is for information only. It does not replace a medical consultation: if in doubt, talk to your doctor.
