This is the last alternative to find sperm. A testicular biopsy consists of taking a small sample of tissue from one or both testicles and examining it under a microscope to evaluate if there are any sperm available.
The previously described procedures can also be carried out in those cases were an ICSI will take place later on, for which the obtained tissue can be frozen; it has also come to help in a great extent on patients with a non-obstructive azoospermia.