Invalid Result
A drug test outcome reported when the laboratory cannot obtain a scientifically valid reading from the specimen and cannot identify a specific adulterant.
Key Facts
- The lab cannot obtain a valid, scientifically interpretable result
- Not the same as positive, negative, adulterated, or substituted
- Usually triggers a recollection, often under direct observation
- Causes include interfering substances, abnormal pH, or immunoassay interference
An invalid result means the laboratory detected something abnormal — unusual pH, possible interfering substances, inconsistent immunoassay responses — but could not establish an interpretable positive, negative, adulterated, or substituted result. The MRO contacts the donor to determine whether a medical explanation (such as a prescribed medication) accounts for the finding. If there is no legitimate medical explanation, the donor is typically sent for an immediate recollection under direct observation. An invalid result by itself is not a violation, but refusing the recollection is a refusal to test.
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