Azoospermia is the complete absence of sperm in the semen and as such means that a man will be completely infertile. The diagnosis of azoospermia is sometimes still made even though as many as 500,000 sperm per ml of semen may have been seen because it is extremely unlikely that the man will be able to father a child naturally with this number of sperm. It’s incredible to realise that millions are needed for any chance of natural conception!