How It Works

How drug test screening is conducted

The most common method of drug testing, urinalysis, can be done at the workplace (at a health unit, for example), a doctor’s office or any other site selected by the employer.  An employee or applicant provides a sample to be tested.  Usually precautions are taken, such as putting blue dye in the toilet and turning off the water supply, to prevent adulteration or substitution of specimens so that collection can be completed in privacy without any direct visual observation by another person.

Under SAMHSA’s guidelines, once a sample is provided, it is sent to a certified laboratory.  The accuracy of drug tests done by certified laboratories is very high, but this certification applies only to the five substances tested for in Federal drug-testing programs and alcohol.

Below are certain procedures required by SAMHSA’s guidelines to ensure accuracy and validity of the testing process:

Chain of Custody: A chain-of-custody form is used to document the handling and storage of a sample from the time it is collected until the time it is disposed.  It links an individual to his or her sample and is written proof of all that happens to the specimen while at the collection site and the laboratory.

Initial Screen: The first analysis done on a sample is called an initial screen.  This one test alone is not always accurate or reliable; there is a possibility of a false positive.  Thus, in the event that the initial screen is positive, a second confirmatory test should be done.

Confirmation Test:  A second, confirmation test (by gas chromatography/mass spectrometry or GC/MS) is highly accurate and provides specificity to help rule out any false positives (mistakes) from the initial screen.  For a test result to be reported as positive, the initial screen and confirmation test results must agree.

Split Sample:  A split sample is created when an initial urine sample is split into two.  One sample is used for the initial screen and, if positive, the second sample is used for the confirmation test.  If there is a positive result, the individual being tested may request the confirmation test be done at a different laboratory.  DOT's alcohol and drug-testing regulations require all tests be performed using a “split sample” collection process.

MRO: In the event that the initial screen and confirmation test are both positive,  MRO, a licensed medical doctor who has special training in the area of substance abuse, then reviews the results, makes sure the chain-of-custody procedures were followed, and contacts the individual to make sure there are no medical or other reasons for the result.  It is only at this point that the MRO may report a positive test result to the employer.  Certain medications can sometimes cause a positive result.  If this is the case, and a doctor prescribed the medicine and the employee used it in the proper amount, the test is reported as negative.

Who benefits from drug testing?



  • Safe working environment
  • Workplace productivity
  • Quality of work
  • Reduce:

  • Health insurance costs
  • Absenteeism and turnover
  • Work related accidents
  • Workplace conflict
  • Thefts and claims



  • Desirability to employers
  • Quick hiring
  • Personal confidence
  • Offer employers:

  • High productivity
  • Stability
  • Safe workplace
  • Reliability
  • Decreased expenses



  • Open discussion about drugs
  • Honesty about drug use
  • Consideration of consequences
  • Provide:

  • A reason to say “no” to drugs
  • Consistent parenting
  • Intervention
  • Opportunity for help
  • Guidance