Idiopathic secondary azoospermia occurrence in men with oligospermia over time.

Men with ≤ 1 M/ml, especially those with low testosterone levels, have a dramatically increased chance of becoming azoospermic with time. Therefore, sperm banking should be recommended in these cases. Men with a sperm concentration above 1 M/ml have low chances of becoming azoospermic, even after 3 or more years.