Azoospermia is one of the possible results of semen analysis. It is a condition during which there are no sperms present in the ejaculate.
Some of the usual causes are:
-primary failure of the testes
-ejaculatory duct obstruction
-previous vasectomy
-missing reproductive cells
It is often interchangeable with aspermia, which is the state of the complete absence of ejaculate during an orgasm.