During male sterilisation surgery (Vasectomy), the tube that carries sperms (Vas deferens) from each testicle is clamped, cut or sealed. This prevents sperms from mixing with the semen that is ejaculated from the penis. An ovum (egg) cannot be fertilised when there are no sperms in the semen. The testicles continue to produce sperms, but the sperms are re-absorbed by the body. Because the tubes are blocked before the seminal vesicles and prostate, one still ejaculates about the same amount of semen. Sexual desire, erectile function and ability to experience orgasm remain unaffected after this surgery.
Vasectomy is a permanent method of contraception (birth control method). Once your semen does not contain sperms, you need not worry about using any other contraceptive.