Drug tests are common procedures used to detect specific substances in a person’s system, serving purposes like pre-employment screening or monitoring. While results are typically “positive” or “negative,” an “inconsistent” result means a definitive interpretation is not immediately possible. This outcome requires further investigation.
Defining “Inconsistent”
An “inconsistent” drug test result means the laboratory cannot definitively determine if a sample is positive or negative for a tested substance. This differs from a “positive” result, which confirms a drug above a specific cutoff, or a “negative” result, indicating no drug was detected or levels were below cutoff. It also varies from an “invalid” result, which suggests an issue with the test procedure or sample integrity, or a “diluted” result, where the sample’s concentration is too low. An inconsistent result points to an anomaly preventing a clear interpretation, necessitating additional review.
Reasons for Inconsistent Results
Several factors can contribute to an inconsistent drug test result. These include issues with sample integrity, such as adulteration (substances added to the sample) or dilution (lowering detectable compound concentration). Intentional tampering, like adding household products or using synthetic urine, can interfere with test mechanisms, leading to unclear results.
Laboratory processing errors are another cause. These can include equipment malfunctions, mislabeling of samples, calibration issues, or human error during analysis. Different laboratories may also employ slightly varying testing processes or cutoff levels, which can sometimes lead to conflicting results.
Certain interfering substances or medications can also produce inconsistent outcomes by interacting with initial screening tests. Prescription drugs like pseudoephedrine, ibuprofen, or some antidepressants can trigger “false positives” on initial immunoassay screens. Their chemical structures can cross-react with screening antibodies, leading to a non-negative result requiring further confirmation. Physiological factors, such as unusual body chemistry or rare metabolic conditions, can also influence test results.
The Next Steps After an Inconsistent Result
When a drug test yields an inconsistent result, a standardized process follows to resolve the ambiguity. The sample is usually sent for confirmatory testing, utilizing more precise methods such as Gas Chromatography/Mass Spectrometry (GC/MS) or Liquid Chromatography/Mass Spectrometry (LC/MS). These advanced techniques accurately identify specific substances and their concentrations, helping to differentiate between true positives and interferences.
A Medical Review Officer (MRO), a licensed physician with specialized knowledge in drug testing, plays a central role. The MRO receives and reviews all non-negative or inconsistent laboratory results. They contact the individual to discuss potential medical explanations, such as prescription medications or other factors. This confidential conversation allows the individual to provide relevant documentation, like prescriptions, which the MRO evaluates. If a valid medical explanation is provided, the MRO may then report the result as negative.
Potential Consequences of an Inconsistent Result
An inconsistent drug test result, while not a confirmed positive, can still lead to various consequences, particularly in employment or legal contexts. If the inconsistency cannot be resolved, it may delay employment or a job offer. Employers often require clear drug test results, and an unresolved inconsistent result might necessitate further testing or a medical evaluation to clarify the situation.
If the inconsistency remains unexplained or is deemed tampering, it could be treated as a refusal to test or even a confirmed positive, depending on employer policies. For instance, a repeated diluted result might lead to withdrawal of a job offer if the individual was instructed not to dilute the sample. Cooperating with the MRO and providing necessary documentation, such as prescriptions, is important to resolve the inconsistency and mitigate potential adverse outcomes.