Pap smears are routine screening tests that are done to detect changes in the cells of the cervix that either represent cancer or that may predispose to the formation of cervical cancer. Cells are sampled by using a brush and spatula and are examined under a microscope. If certain atypical changes are seen in the cells, then the presence of HPV (Human Papilloma Virus) may be tested for on the same specimen. This is done because persistent HPV infection (with a high-risk strain of the virus) has been shown to be a central factor in the development of cervical cancer. Depending on the results of the cell examination and the HPV testing, further examination may be recommended (such as with a colposcopy or biopsy
As sexual activity and HPV transmission are so closely linked, it is recommended that all women start receiving Pap smears starting within 3 years of having sexual intercourse or at age 21, whichever comes first. Generally Pap smears are repeated on an annual basis until the age of 30; at that point some doctors
recommend that they can be spaced out to every 2-3 years if there are 3 consecutive negative tests.