Q: I had a herpes test done about three months ago when I started dating my new girlfriend. The results came back negative. I have been faithful to her, and I am certain she has been faithful to me. However, I noticed some sort of blister in my genital area. Before I go back to my doctor and get tested again, I’d like to ask a few questions. Could this be herpes? If so, how come the test I took a few months ago did not give me a positive result? Is it possible to carry the herpes virus and not know it for several months?

J. Godfrey

Phoenix, Arizona

A: While it is a great sign that your test came back negative, there is still a possibility that you could have herpes. The important thing to realize about blood tests is that they have a window period. The window period is how long after an exposure you need to wait before getting a reliable test result. With traditional herpes tests, the window period is usually 6-12 weeks.

That said, if you were to take a test one or two weeks after your exposure the test would probably come back negative because you tested too early. If this is a possibility in your case, a follow up test is definitely a good idea. If you do not want to visit your personal doctor again for the test, we can provide the exact same screen at a reasonable cost and everything is completely private and confidential.