Tests to Diagnose Genital Herpes


Genital herpes is a common STD; however, many people who have this sexually transmitted disease don't know they have it. Genital herpes frequently has no symptoms, so you can be infected and contagious without knowing it. When symptoms do occur, they can easily be mistaken for something else. Without adequate testing you may be told you are infected with genital herpes and not be, or the other way around.

If you have sores on your genitals, your health care provider can perform tests to determine if you have genital herpes.

Genital Herpes Tests

Tests used to diagnose or screen for genital herpes include:

  • PCR blood test: The PCR blood test can tell if you have genital herpes even if you don't have symptoms. The PCR test looks for pieces of the virus's DNA. This is the most common test used to diagnose genital herpes and is very accurate.
  • Cell culture: During the exam, your health care provider can take a sample of cells from a sore and look for the herpes simplex virus (HSV) under a microscope.

Cell culture or PCR test may give a false-negative result if the sores have begun healing or if you are recently infected. It takes several weeks for HSV antibodies to show up in the blood. A false-negative test shows you don't have the condition when in fact you do. False-positive test results are possible, too. If you test positive, but your risk for getting the virus is low, you may need to be tested again.

PCR and cell culture tests show that you have been exposed to the virus at some point. It is difficult to tell from these tests when the exposure may have occurred. You may have had HSV for many years before you have your first noticeable outbreak. Or you may have never had an outbreak but still may be contagious to a sexual partner.


Other Genital Herpes Tests

Antibody tests are also used to diagnose genital herpes. Antibodies are proteins produced by the immune system in response to an infection. With direct fluorescent antibody testing, a solution containing HSV antibodies and a fluorescent dye is added to the sample of cells. If the virus is present in the sample, the antibodies stick to it and glow when viewed under a special microscope.

Antibody tests can tell the difference between the two types of HSV. It's important to know which type you have. If you're infected with type 2 (HSV-2), you may have outbreaks more often than you would with type 1 (HSV-1), which refers to cold sores that appear on the lips and around the mouth. What's more, knowing which type you have gives a clue as to how you were infected. HSV-1 usually infects the genitals through oral sex, and HSV-2 usually is passed on during vaginal or anal sex.

Unfortunately, an antibody test (usually done on blood samples) only tests whether you have been exposed or ever had herpes virus. It is helpful, but does not diagnose a specific outbreak.

Other tests include one that can detect HSV in saliva, tears, and urine.

Before you visit your health provider to be tested for genital herpes, first read Preparing for Your Doctor Visit. To get the most out of your exam, print and take along 10 Questions to Ask Your Doctor.

If you are diagnosed with herpes, you have many decisions to make. Do you want to take medication? Which one? Should you take medicine every day or only when you have symptoms? To better understand your choices, see Treatment Options and this helpful chart, Medications Chart.

For more information and help understanding words you may hear about genital herpes, see Resources and the Glossary.

WebMD Medical Reference Reviewed by William Blahd, MD on September 6, 2016




The Merck Manual of Diagnosis and Therapy. 

Reuters Health. 

Terri Warren, RN.

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