How Accurate is a Single Pap?
Whenever you are getting screened, those at risk for abnormal tests are probably going to get the most accurate testing. In other words, the tests themselves are very accurate. Pap tests can pick up precancers, cancers, infections, and irritations. The infections that can be tested for include the Human Papilloma Virus (HPV). If you want to know how accurate your personal pap test is, there are a lot of considerations, such as are you at high or low risk, and basically you and your gyno will have to discuss your specific case to really get this answer together.
HPV is a DNA virus that infects skin and mucousal tissues and causes cell changes that lead to what is known as cell proliferation (overgrowth) and conversion to neoplastic changes (premalignant and malignant). HPV is the source of virtually all of cervical cancer. If we add tests for the most cancer causing HPV we can almost double the rate of pick up of the abnormal pap that are missed by the single screen. More precise tests are coming, you may want to know, do you have HPV16, 18, 45, or perhaps do you have p16NK4a34. Now it will be awhile until we can tell you the latter.
Degree of accuracy of the pap test depends if you are talking a single pap test, ever, or just one pap in a series of pat tests. You should have confidence in your pap, by getting a pap test you are likely to prevent cervical cancer, even if a precancerous condition arises. Basically the pap test reduces the rate of cervical cancer by about 75%, by alerting testing in the precancerous, non-invasive stage. A pap can be fairly insensitive at picking up what is wrong on any single test, inaccuracy can be as high as missing 5 to 15% of cases. But once you have had several tests, it would be very rare to have a serious problem with the cervix that is missed.
Women are exposed to the HPV virus when they are first sexually active. Most abnormal pap smears thus occur in young women. However, as we age, our immune systems weaken as we get older, and we begin to see HPV infections again as women enter their menopause.