A vasectomy is a surgical procedure to tie the vas deferens of a man to cause sterility by preventing the sperm from leaving the testes. The vas deferens is located in the testicle as a small tube that carries the sperm to the semen. The procedure is recommended for adult men who are certain that they wish to prevent future pregnancies (permanent sterilization). There will still be a fluid ejaculate, but no sperm will be in the fluid, so the man cannot impregnate his partner.