Other causes include: 1  A fall against a hard surface in the seated position, such as a fall from a horse. 2  A direct blow to the coccyx, such as in contact sports.  Straining or dislocating the coccyx. This can happen due to poor posture while driving, or repetitive injury from sports such as rowing or cycling.
1 Positive test results also can mean that the amount of a substance being tested for is higher or lower than normal. 2  A negative test result means that the substance or condition being tested for was not found. false-negative test result may suggest that a person does not have a disease or condition being tested for when he or she does have it. For example, a false-negative pregnancy test result would be one that does not detect the substance that confirms pregnancy, when the woman really is pregnant.
You will note below that a saliva drug test can positive drug results in a matter of hours. A urine drug test can show positive results in a matter of days. *There are many factors that affect the actual window of detection (see How Long Do Drugs Stay In Your System - Drug Detection Times for more information). This chart is meant to give relative results for the majority of cases. There are always situations that affect the actual drug test window.