The test is able to detect in urine the presence of marijuana, PCP, amphetamines, cocaine, heroin, codeine and morphine. Urine samples collected at home are sent to a special laboratory for extensive testing. Test results may be obtained by calling a toll-free number and using an anonymous identification number supplied in the kit. Counselors carefully explain tests results, including false positives and negatives, and will make referrals for drug abuse counseling or medical treatment. When performed correctly, home pregnancy tests are about 95-100 percent accurate, says Richard White, M.D., a gynecologist and obstetrician at The Emory Clinic Perimeter.
Most tests ask users to test first morning urine on the first day after a missed period.
False negative results may occur if insufficient time has elapsed since conception, reading results before the allotted time or excessive shaking of the urine sample. If the test reads negative after instructions were carefully followed, manufacturers usually recommend users wait a specified number of days before retesting. The same mercury or aneroid sphygmomanometers used in conjunction with stethoscopes by health professionals to gauge blood pressure are available to the consumer to test ones' own blood pressure. The devices are highly accurate, but may be a challenge to the untrained. The automated electronic or digital meters also available are much simpler to use, says internist Warren Davis, M.D., of The Emory Clinic Perimeter, and still serve the purpose of allowing patients to monitor any significant changes in their own blood pressure.