Most health care organizations recommend women begin regular Pap testing at age 21. If you're a virgin — meaning you haven't had sexual (vaginal) intercourse — you may have a low risk of cervical cancer, but you can still consider testing.
The purpose of a Pap smear is to collect cells from your cervix, which is the lower end of your uterus. The cells collected in a Pap smear can detect if you have cervical cancer or suspicious cells that indicate you may develop cervical cancer.
In most cases, cervical cancer is caused by a sexually transmitted infection called human papillomavirus (HPV). If you've never had any type of sexual intercourse, you're unlikely to have HPV. However, there are other risk factors for developing cervical cancer, such as family history and smoking, so talk to your doctor if you have concerns.
For effective cervical cancer screening, many organizations recommend an initial Pap smear at age 21. Discuss when to begin cervical cancer screening with your doctor. Together you can decide what's best for your particular situation.
http://www.mayoclinic.org/tests-procedures/pap-smear/expert-answers/pap-smear/faq-20057782
