How is an AIDS Test Performed?

Getting the Sample

Usually, an AIDS test is performed by taking a blood sample and evaluating it in a laboratory. To pull the sample, blood is drawn into a syringe via a needle injected into the arm. The blood sample is sent to a laboratory, where it is evaluated and the results determined.

Blood and Urine Testing

Though a blood test is the most common method for an AIDS test, some tests may also be done using a sample of saliva or urine. A saliva sample can be taken by swabbing the outside of the gums with a special tool, and a urine sample can be collected in a cup.

What the Test Looks for

In either a blood, saliva or urine sample, the test looks for antibodies to HIV. When the human immunodeficiency virus enters the body, the immune system in response creates antibodies to defend against the virus. If these antibodies are found in the body's fluids, then the person has HIV or AIDS. These antibodies are typically evident in bodily fluids between three and eight weeks after you've been exposed to the HIV virus. Earlier than that, more sensitive tests (like the p24 antigen test or HIV RNA test) may be needed to test for AIDS and HIV.

Usually, results can be available in as little as 20 minutes, according to the National HIV and STD Testing Resources. But, some tests may take several days. If your test shows a positive result, you'll need a second test to confirm the diagnosis.