The venereal disease research laboratory (VDRL) test is designed to assess whether you have syphilis, a sexually transmitted infection(SIT). Syphilis is caused by the bacterium Treponema pallidum. The bacterium infects by penetrating into the lining of the mouth or genital area.

The VDRL test doesn’t look for the bacteria that cause syphilis. Instead, it checks for the antibodies your body makes in response to antigens produced by cells damaged by the bacteria. Antibodies are a type of protein produced by your immune system to fight off invaders like bacteria or toxins. Testing for these antibodies can let your doctors know whether you have syphilis.