In men who have no spermatozoa in the ejaculate, sperm need to be retrieved either form the epididymis or the testes. When the etiology of azoospermia is obstructive (blockage to the canals bringing the spermatozoa from the testes to the ejaculate) sperm can be retrieved from the epididymis using a needle aspiration technique. (TESA)
In men with azoospermia due to defective sperm production, sperm can be obtained from the testes usually with an open surgical procedure (TESE). Both procedures are performed under general anesthesia.
While sperm can be retrieved in almost 100% of subjects with obstructive azoospermia, only 40-50% of the subjects with nonobstructive azoospermia will yield viable spermatozoa.
Azoospermia may be associated with certain genetic disorders. There may be mutations in the cyctic fibrosis gene in men with obstructive azoospermia. Chromosomal abnormalities and Y-chromosome microdeletions may be associated with nonobstructive azoospermia. It is advised that genetic testing be undertaken in all men with azoospermia.