Infertility in some men may be due to an interruption in the sperm transport passages as a result of either a previous male sterilization operation (vasectomy), an anatomical birth abnormality (absence of the vas deferens), or a spinal/pelvic injury or operation.
In these cases sperm may need to be surgically collected from inside a man’s genitals instead of waiting for the sperm to be ejaculated out. The sperm requirement for egg fertilization has dropped from hundreds of thousands for in vitro fertilization (IVF), to one viable sperm required for ICSI when combined with IVF. Sperm can be aspirated with a needle from the testicle or from the vas deferens (the tube that carries the sperm from the testicle).
The man is given some drugs to sedate him and some local anesthesia is also used to numb the area. Then a small needle is inserted and sperm is aspirated. There should be no severe pain. The procedure generally takes about 30 minutes.