False-positive drug tests

Biological false positive serological tests for syphilis among drug addicts.

False Positive and False Negative Results in Urine Drug Screening Tests: Tampering Methods and Specimen Integrity Tests

Urine drug screening can detect cases of drug abuse, promote workplace safety, and monitor drugtherapy compliance. Compliance testing is necessary for patients taking controlled drugs. To order and interpret these tests, it is required to know of testing modalities, kinetic of drugs, and different causes of false-positive and false-negative results. Standard immunoassay testing is fast, cheap, ...

False-positive and false-negative rates in meconium drug testing.

To determine the number of false-negative results produced by inefficient extraction of drugs from meconium, three published procedures were compared by using previously confirmed positive and negative meconium specimens. The methods were not equivalent in their ability to extract drugs from the matrix. To determine the number of false positives reported by the use of screen-only (unconfirmed) ...

False-positive urine pregnancy tests - clinicians as detectives

Reliably diagnosing pregnancy in women presenting with nonspecific abdominal pain can be lifesaving. If diagnostic tests are unreliable, however, valuable time and resources can be wasted pursuing unnecessary and potentially harmful interventions. After four false positive-urine pregnancy tests in one week, we began investigating the laboratory's entire process involving the UPreg tests. We dis...

The biological false positive reaction to serological tests for syphilis.

Acute and chronic biological false positive reactions to serological tests for syphilis are discussed. Three cases are presented, one showing an acute and one a chronic reaction, and one in which it was not possible to determine if the reaction was acute or chronic. Once a biological false positive reaction is found, serum from the patient should be tested at intervals for at least six months t...