A vasectomy doesn't provide immediate protection against pregnancy. Use an alternative form of birth control until your doctor confirms there are no sperm in your semen. Before having unprotected sex, you'll need to wait up to three months or longer and ejaculate 20 times or more to clear any sperm from your semen.

Most doctors do a post-surgery check three months after surgery to be certain that no sperm are present. You'll need to give your doctor sperm samples to examine. To produce a sperm sample, your doctor will have you masturbate and ejaculate into a container. Your semen is then examined under a microscope to see whether sperm are present.

Vasectomy is an effective form of birth control, but it won't protect you or your partner from sexually transmitted infections, such as chlamydia or HIV/AIDS. For that reason, you should use condoms if you're not in a committed relationship — even after you have a vasectomy.

Feb. 09, 2013