I am a 37 year old healthy female. This year I had a normal pap smear but a positive HPV-18 test. My doctor is performing a follow up colposcopy as a precautionary measure. I'm looking for more information about exactly what my results mean. I've never had an abnormal or inconclusive pap smear in my life. At age 30 I had a positive high-risk HPV test, but I had negative high-risk HPV tests at ages 31 and 34. Furthermore, I was vaccinated against HPV in my late teens/early 20's. 

I suppose my main questions are the few listed below, and I am grateful for any insight you can provide:

This is actually a pretty common situation. There probably is little if any important health risk in this situation. STD specialists don't typically manage cervical HPV infections or pap smears, however; of course you also should discuss this with your gynecologist. His or her plan for colposcopy is, I believe, a cautious and conservative plan; with otherwise normal cervical cytology (pap smear), I'm not sure how many gyns would do colposcopy as opposed to just periodic repeat paps with HPV testing.

It's quite common for HPV to reactivate after intervening negative test results. In other words, new appearance of HPV doesn't necessarily mean a new infection. Having a positive result for HPV198 despite being vaccinated against HPV suggests you acquired it before you were immunized, and that this represents late recurrence of that infection. New acquisition of a vaccine-protected HPV type is virtually unheard-of:  all research indicates the vaccine is 100% effective against the types covered by the vaccine.

Those comments partly address your specific quesitons, but to be explicit:

1. Many or most cervical HPV infections do not cause abnormal cellular changes. Your normal pap smear is a good sign, suggesting a very low risk of future cervical cancer.

2. As I said, I can't say how many gyns would do colposcopy in this situation. I would have thought it uncommon, but as I also noted, we STD specialists generally don't manage abnormal pap smears or cervical HPV infections.

3. In absnce of cellular changes, the chance of cancer is low.

4. Intermittent reactivation of a chronic HPV infection isn't rare. As best known from available research, long delayed reactivation is not known to imply high risk for repeated reactivations in the future.

5. If you received less than 3 doses -- and especially if you got only one dose -- it is possible you were incompletely protected. With 3 doses of the vaccine completed within a year. As noted above, your HPV18 infeciton probably pre-dates vaccination -- assuming you had become seually active before the vaccine series was completed.

Sorry that some of these replies may not be entirely satisfying; there's a lot still unknown about HPV and how it behaves. But I ihope these comments are somewhat helpful. Let me know if anything isn't clear.

HHH, MD

Thank you very much for answering my questions even though they fall outside the 'standard' realm of your expertise. I once saw a presentation on female sexual health by a physician whose first slide stated "cervical cancer is a sexually transmitted disease." Even though I knew immediately that this was an un-nuanced view, and that it's the HPV and not the cancer that's transmitted, I've never been able to "un-see" her presentation. That may explain why I came here first. 

Your information did a lot to dispel my anxiety. 

Interesting to hear of the new ACS guidelines. I'll check it out. Most of your comments indicate your evolving and correct understandings.

In principle, anyone with any newly diagnosed STD should be tested for other common or serious ones. However, HPV is a semi-exception:  because so many newly diagnosed infiections are not recently acquired, and because HPV is so prevalence regardless of sexual history, it's a very poor predictor of other STDs. If you've otherwise been at risk (new partner, uncertainty about a partner's risks, etc), having routine testing for gonorrhea, chlamydia, HIV and syphilis makse sense. But not because of your HPV infection per se. Another safety factor is that you've obviously had direct inspection of your cervix, presumably without visible abnormality. That doesn't exclude gonorrhea, chlamydia, trichononas, etc, but significatly reduces the chance. And your test results from 2 years ago also essentially eliminate any serious chance you're infected now, if no risky exposure in the meantime. That said, if these experiences have raised your concern, no matter how low your risk, I'm sure your Gyn would do it.