This technique is used to deal with male INFERTILITY 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.