The VDRL test checks blood or spinal fluid for an antibody that can be produced in people who have syphilis. This antibody is not produced as a reaction to syphilis specifically, so the test result could be abnormal for reasons other than syphilis. Rapid plasma reagin (RPR) test. Negative: Nontreponemal antibodies not detected. Positive: Specimen reflexed to determine rapid plasma reagin titer.