How ICSI Works. Since ICSI is always used with in vitro fertilisation, the process starts with preparation for this procedure. The woman is given fertility drugs to stimulate egg follicle development and ovulation.Her mature ova are then retrieved to use during ICSI.In additional preparation for ICSI, sperm is collected from the man.CSI is currently the most successful treatment for male infertility, with fertilisation rates of 60%-70% depending on quality of the sperm used. However, once the egg is fertilised, the success rates of ICSI in conjunction with IVF remain the same as conventional IVF – a 20%-25% chance of live birth.