In some individuals sperm cannot reach the semen because there is a blockage somewhere in the testicle or part of one area is absent or abnormal. In cases such as this the diagnostic semen analysis will show that there were no sperm present this is known as Azoospermia.
In such cases sperm can be artificially removed from the area situated directly before the blockage. Sperm recovered from the testes in this manner are less mature than those normally found in semen because they have had less time to develop. They are usually not capable of fertilising an egg naturally. For this reason the sperm will be used in conjunction with ICSI (intra-cytoplasmic sperm injection).