There are two types of azoospermia, considering where the problem takes place. Therefore, we distinguish between secretory azoospermia (a.k.a. non-obstructive azoospermia) and obstructive azoospermia.
The secretory azoospermia or non-obstructive is the most serious type, as the testis do not produce spermatozoa. The causes can be either hormonal or testicular.
The other type, obstructive azoospermia, refers to an effective production (the testicles of the patient do produce sperm), that is not ejaculated because of a problem with delivery; the ducts that transport sperm to the urethra are not working properly.