ICSI (intra-cytoplasmic sperm injection) involves the injection of a single sperm directly into the oocyte. This procedure is used for men with poor quality sperm, or in whom sperm has had to be collected directly from the testicle. The process is initially the same as for an IVF cycle up until the fertilisation stage of the cycle, where the scientist performs ICSI. 

On average, about 70% of injected eggs are successfully fertilized by the ICSI process.  This has been successful in overcoming previously hopeless situations for couples with severe male sub-fertility.  It can also be used in situations where there has been unexplained failure of fertilization of apparently normal eggs by normal looking sperm.