Microinjecting one spermatozoon into the oocyte is a similar treatment to IVF except for the way in which the oocytes are inseminated. Only one living sperm cell is needed for each oocyte. It is suitable in cases of very low sperm count, including testicular biopsy.
The chances of success with ICSI are the same as with conventional IVF. However, it is important to take into account that couples undergoing ICSI have a much more serious primary problem: difficulty to achieve fertilization using the man’s sperm.