Intracytoplasmic sperm injection (ICSI) is the most signiﬁcant therapeutic advance in male INFERTILITY treatment in the past 30 years. The technique is used when in vitro fertilisation (IVF – see under ASSISTED CONCEPTION) is not possible because the man has very few, motile, normal sperm (see SPERMATOZOON), or when previous attempts at IVF have not produced a fertilised EMBRYO. ICSI requires a single sperm which is injected directly into the cytoplasm of an egg previously retrieved from the woman. Once fertilised, the embryo is transferred to her UTERUS. For men with no sperm in the semen, it may be possible to retrieve sperm by needle aspiration of the EPIDIDYMIS under local anaesthetic (see ANAESTHESIA). Other techniques involve microsurgical retrieval from the epididymis or TESTICLE under a general anaesthetic. Potential complications include scrotal pain, bruising, HAEMATOMA formation and infection. ICSI and surgical sperm-retrieval require extensive training and expertise and is currently available in only a few selected
infertility units. Safety concerns relate to a higher-than-expected rate of abnormalities in the SEX CHROMOSOMES after ICSI, and also the potential risk of transmitting paternal genetic defects in the Y chromosome to sons born after ICSI.