What ICSI does
In conventional IVF, eggs and sperm are put together and nature sorts it out. In ICSI the embryologist immobilises one sperm, draws it into a micropipette and injects it into the egg's cytoplasm. The rest of the cycle is identical.
When it is justified
- Severe sperm abnormality: very low count, very poor motility, overwhelmingly abnormal forms.
- Failed fertilisation in a previous conventional IVF cycle.
- Sperm retrieved surgically from the testis or epididymis, where they are few and barely motile.
- Previously vitrified eggs, whose outer shell hardens on freezing.
When it is not
This is what many couples learn too late. With normal sperm, ICSI improves the fertilisation rate but not the birth rate: trials show no advantage, for extra cost and extra handling. It has nonetheless become the majority technique in many countries, far beyond its indications. Asking why ICSI is being proposed in your case is a fair question, and a good clinic answers it without bristling.
IMSI and the other add-ons
IMSI is ICSI with the sperm selected at very high magnification. Its benefit remains disputed and it is not standard. The same goes for several options often billed as extras — assisted hatching, embryo glue, hyaluronic acid selection, time-lapse incubators. None has shown a clear effect on live birth in the general treated population.
And for the child?
Children conceived by ICSI do well. Follow-up studies find a small excess of certain malformations, part of which is explained by male infertility itself rather than by the technique: a man carrying a Y-chromosome microdeletion will pass it to his sons. That is why a karyotype and microdeletion screening are offered before ICSI for severely abnormal sperm.