As for when to have the test: every year, every other year, every third year (or every fifth year which I do not recommend) will depend on your age, your prior tests and whether you are getting an HPV test also. The guidelines as to when to have a pap do vary very slightly from one medical society to the next. And you can have the discussion with your gyno as to which guideline applies best to you. So it's important if you are a mom of a young woman, ask your gyno what she currently recommends for your daughter, it's changed over what she recommended for you! The current guidelines can be summarized like this: get your first pap at age 21, and then begin getting every two years. After thirty, if you are low risk, and have been getting normal pap smears, you can get pap smears even every 3 years.
Pelvic exams to screen for STDs, to check your uterus and ovaries are still done every year. Women under the age of 25 and women with new partners should have tests for gonorrhea and chlamydia at the time of the pap, and it can often be tested for on the same swab. For those too young for pap smears (under the age of 21) STD testing can be done on urine. If you are age 65 or 70, you may be low enough risk to stop pap smears; you would not want to stop getting pelvic examinations. If you have had abnormal pap smears, if you have immune compromising conditions, or HIV, you need to keep getting pap tests every year.
The FDA has approved adding HPV testing to your pap after the age of 30, and it is a separate test you may need to ask for as most labs are set up only to do that test if your pap test comes back ambiguous. It is now also approved to have type specific HPV testing: so not just a pap or pap plus HPV but a typing of the HPV virus to see if you have HPV 16 or 18. It is also approved to have the activity of any HPV virus infection of the cervix tested which can tell you how likely it is that you have moderate or severe cervical dysplasia. HPV 16 and 18 are responsible for a large percentage of cervical cancers. If you had the HPV vaccine you have been immunized against these viruses. If you had your vaccine after you had sexual contact or intercourse, you may have already picked one or more of of these HPV types up. There is no specific cure, so it's important to have testing if you have had sex with a new partner in the past few years. Keep posted, as the guidelines do not yet say when to get pap tests if you have had the HPV vaccine, but we are anticipating that in the future they will recommend fewer pap smears if you were vaccinated.