A cancelled drug test is a determination made by a Medical Review Officer (MRO) that the result is neither positive nor negative. This outcome signifies a procedural or technical flaw so serious that the integrity or validity of the specimen or the testing process cannot be guaranteed. The test is essentially voided, meaning it cannot be used by an employer to take action against an individual or to fulfill a requirement for a verified negative result. A cancelled result prevents the MRO from making a definitive finding.
Errors During Specimen Collection
Cancellation can originate immediately at the collection site due to observable physical issues with the specimen itself. One common error is a Quantity Not Sufficient (QNS) finding, where the donor fails to provide the minimum required volume of urine. For a proper split specimen collection, at least 45 milliliters is necessary. If the donor is unable to produce this volume, the collection is discarded, the test is cancelled, and a new collection attempt is required.
The temperature of the specimen is another immediate integrity check. Freshly collected urine must register a temperature between \(90^\circ\text{F}\) and \(100^\circ\text{F}\) (\(32^\circ\text{C}\) and \(38^\circ\text{C}\)) within four minutes. A temperature outside this window suggests the sample was substituted or altered externally. If the temperature is out of range, the collector initiates an immediate, directly observed recollection.
Procedural errors committed by the collector can also invalidate the test. Failure to properly observe the donor when required, or not completing all necessary steps on the Custody and Control Form (CCF), creates a fatal flaw. These mistakes compromise the ability to prove the specimen belongs to the donor and was collected without tampering. Such errors prevent a definitive result from being issued, resulting in cancellation by the MRO.
Breaks in the Chain of Custody
The Chain of Custody (COC) is the administrative paper trail that legally documents the handling and transfer of the specimen. Any break in this protocol can lead to a cancelled test because the MRO cannot confirm the sample’s identity or integrity. Missing or mismatched signatures are frequent causes, such as the collector or donor failing to sign the Custody and Control Form (CCF) at designated transfer points. Every individual who handles the specimen must sign and date the form, creating an unbroken accountability record.
Improper labeling or identification is another administrative fatal flaw. If the unique specimen identification number on the collection bottle seal does not match the number recorded on the CCF paperwork, the sample cannot be definitively linked to the donor. This discrepancy makes the result legally unverifiable, regardless of the chemical analysis performed. The MRO must cancel the test because the fundamental link between the person and the sample is broken.
Security breaches during handling and transport also constitute a break in the chain of custody. Specimen bottles are sealed with tamper-evident tape that must remain intact until the lab receives them. If the security seal is broken, damaged, or missing upon arrival, it suggests the sample could have been accessed and compromised. Furthermore, the use of expired collection kits or a non-standard CCF can result in automatic cancellation by the MRO.
Laboratory Validity Testing Failures
When a specimen reaches the laboratory, it undergoes integrity checks known as specimen validity testing (SVT) before drug analysis begins. If these checks fail, the lab reports an “Invalid Result,” which the MRO uses to cancel the test. One primary validity check is for abnormal pH levels, which measure the acidity or alkalinity of the urine. Normal human urine pH typically falls between \(4.5\) and \(8.0\); a pH outside this physiological range, such as below \(3\) or above \(11\), indicates the presence of a chemical adulterant intended to mask drug presence.
Specific gravity (SG) is another measure that assesses the concentration of dissolved solids. The normal SG range is typically between \(1.003\) and \(1.030\). An SG that is too low, combined with low creatinine, suggests excessive dilution. If the SG is outside the acceptable parameters, the lab reports the specimen as substituted or adulterated, preventing a valid drug result.
The concentration of creatinine, a waste product of muscle metabolism, is always measured as a marker of a true urine specimen. A creatinine concentration below \(20 \text{ mg/dL}\) is considered dilute. If the level is extremely low, such as below \(2 \text{ mg/dL}\), it is physiologically inconsistent with normal human urine, leading to a report of “substituted.” The lab also tests directly for oxidizing adulterants, such as nitrites or glutaraldehyde, which are foreign chemicals designed to destroy drug metabolites.
In rare instances, technical laboratory issues can also lead to a cancelled test. These include equipment malfunction, contamination of reagents, or an inability to confirm the initial result when the split specimen is tested. When the laboratory reports a finding of “rejected for testing” or “invalid result” due to these technical problems, the MRO must cancel the test.