Vasectomy is a small operation that prevents sperm from reaching the semen that ejaculates from the penis. Sperm is still present, but not sperm. After vasectomy, the testicles still produce sperm, but they are sucked up by the body. Each year, more than 500,000 men in the United States choose vasectomy for contraception. Vasectomy prevents pregnancy better than non abstinenc contraceptive methods.