What Does An Inconclusive Drug Test Mean

By Bella Sungkawa | Published: | Drug Testing | 2 min read

Short Answer

An inconclusive drug test result occurs when a laboratory cannot definitively confirm or reject the presence of prohibited substances. This outcome may stem from low drug concentrations, sample issues, or procedural errors, and it typically leads to retesting or additional analysis.

Complete Explanation

An inconclusive drug test result indicates that the testing laboratory was unable to reach a clear positive or negative determination for the targeted substances. This uncertainty can arise at the initial screening stage or during confirmatory analysis and does not automatically imply drug use.

  • Definition:
    An inconclusive drug test result indicates that the analytical laboratory was unable to reach a clear positive or negative determination for the target substances.
  • Common Causes:
    Low drug concentrations near the detection limit, sample degradation, adulterants, or procedural errors during collection, handling, or analysis.
  • Testing Process:
    Initial immunoassay screens are followed by confirmatory methods such as gas chromatography‑mass spectrometry (GC‑MS); an inconclusive result may arise at either stage.
  • Implications:
    Employers, clinicians, or legal authorities may request a retest, a new specimen, or additional confirmatory testing before making decisions.
  • Recommended Actions:
    The individual should be informed of the result, offered a chance to provide a new sample, and advised on any relevant policies or medical considerations.

Common Misconceptions

Myth

An inconclusive result means the person definitely used drugs.

Fact

It only indicates uncertainty; the result could be due to technical factors rather than actual drug use.

Myth

Inconclusive results are rare and only happen with cheating.

Fact

They occur with measurable frequency in both employment and clinical settings, often because of low concentrations or sample issues.

FAQ

What should I do if I receive an inconclusive drug test result?

You should be notified in writing about the inconclusive status, be offered a chance to provide a new specimen, and be informed of any retesting procedures required by the testing program or employer.

Can an inconclusive result be appealed or contested?

Yes. Most testing programs allow the individual to request a review, which may include a repeat analysis of the original sample (if retained) or collection of a fresh specimen for confirmatory testing.

Do inconclusive results affect employment decisions?

Policies vary, but most reputable employers treat an inconclusive result as a non‑definitive outcome and will typically wait for a conclusive result before taking disciplinary action.

References

  1. U.S. Department of Transportation, Drug and Alcohol Testing Handbook, 2022.
  2. Substance Abuse and Mental Health Services Administration (SAMHSA), Guidelines for Workplace Drug Testing, 2021.
  3. World Anti‑Doping Agency (WADA), Technical Document TD2023, 2023.
  4. Miller, J. & Smith, L., ‘Interpretation of Inconclusive Drug Test Results’, Journal of Analytical Toxicology, vol. 45, no. 2, 2020.
  5. American Society for Testing and Materials (ASTM), Standard Practice for Drug Testing, ASTM E2775‑20.

Related Terms

Immunoassay
A rapid screening technique that uses antibodies to detect the presence of specific drug metabolites in a biological specimen.
Confirmatory testing
A more specific analytical method, such as GC‑MS, used to verify positive or ambiguous screening results.
Detection limit
The lowest concentration of a substance that can be reliably distinguished from zero by a particular analytical method.

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