Serum herpes simplex antibodies is a blood test that looks for antibodies to the herpes simplex virus.

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm.

Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

The sample is taken to the laboratory and tested for the presence and amount of antibodies.

No special preparation is needed for this test.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

The test is done to find out whether a person has ever been infected with oral or genital herpes.

It looks for antibodies to herpes simplex virus 1 (HSV-1) or herpes simplex virus 2 (HSV-2). This test does not detect the virus itself.

A negative test means you have not been exposured to the herpes virus.

A positive test means you have been infected with the herpes simplex virus recently or at some point in the past. Certain patterns of antibodies can sometimes help determine whether the infection is recent.

Approximately 70% of adults have been infected by HSV-1 and have antibodies against the virus. About 20% of adults will have antibodies against the HSV-2 virus.

If the infection occurred very recently (within a few weeks to 3 months), the test may not pick up antibodies, but you may still be infected. This is called a false negative.

Herpes simplex virus stays in your system once you have been infected. It may be dormant and cause no symptoms, or may flare up and cause symptoms. This test cannot tell whether you are having a flare-up.

HSV-2 usually causes genital herpes, whereas HSV-1 usually causes cold sores (oral herpes). However, some cases of genital herpes are caused by HSV-1 and vice versa. Because certain antibody tests for herpes simplex can't tell HSV-1 from HSV-2, the results of the tests should be interpreted carefully and you should discuss them with your health care provider.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

While HSV-1 and HSV-2 are usually only active from time to time, once they're in your system, they stay there for the rest of your life.

Ask your doctor what steps you need to take if you develop symptoms. Ask how to decrease your risk of spreading the virus to other people. Condoms may not fully protect against HSV.

Wald A, Ashley-Morrow R. Serological testing for herpes simplex virus (HSV)-1 and HSV-2 infection.Clin Infect Dis 2002;35 (Suppl 2):S173-82.

Turner KR, Wong EH, Kent CK, et al. Serologic herpes testing in the real world.  Validation of new type-specific serologic herpes simplex virus tests in a public health laboratory. Sex Trans Dis 2002;29:422-425