As for the frequency of fertility testing to verify a successful vasectomy, there is no clear consensus on this matter. It is generally recommended to wait three months after the vasectomy before undergoing a semen analysis to allow all sperm to clear the system. Depending on the results, a repeat test may be needed to ensure that the sperm count has remained at zero. After this initial test, your doctor can advise on when you should undergo subsequent testing to ensure that the vasectomy remains effective. If you have any concerns or questions, it is best to speak with your doctor, who can provide personalized recommendations based on your individual circumstances.