Workplace drug screening uses a standardized coding system to communicate results efficiently to employers and agencies. Understanding the specific meaning of these designations is necessary to correctly interpret the final report.
What the Code XM Signifies
The code XM, or a similar designation, signifies that the test has been officially “Canceled” or resulted in an “Invalid Result.” This outcome is fundamentally different from a positive or negative finding, as it means the laboratory or the Medical Review Officer (MRO) could not make a determination about the presence or absence of substances. A canceled test is rendered null and void, meaning the process was compromised and yielded no usable information. It indicates a procedural failure rather than clearance or a positive result. The MRO is the physician responsible for reviewing laboratory results and is the only party authorized to confirm the cancellation.
Reasons for an XM Designation
A test is designated as canceled when a “fatal flaw” or uncorrectable error occurs during the collection or analysis process, compromising the specimen’s integrity or the chain of custody. One common issue involves compromised sample integrity, such as a urine specimen whose temperature is outside the acceptable range of 90°F to 100°F immediately after collection. A temperature outside this range suggests the sample may have been tampered with or substituted, leading to immediate rejection. Another physical flaw is insufficient specimen volume, where the collected urine is less than the required 45 milliliters needed for both initial screening and a potential confirmatory test.
Most fatal flaws relate to documentation and procedural lapses that break the legal Chain of Custody (COC). These breaches ensure the sample cannot be legally verified as belonging to the donor throughout the entire process. Examples include the collector failing to print and sign their name on the Custody and Control Form (CCF), or the specimen’s unique identification number on the bottle seal not matching the number recorded on the CCF paperwork. The MRO will cancel the test if the security seal is broken, missing, or shows evidence of tampering, suggesting the sample’s integrity was compromised after collection.
Required Actions Following a Canceled Test
When a test result is designated as XM, the Medical Review Officer reports the cancellation to the employer or requesting agency and provides instructions for the next steps. For pre-employment, return-to-duty, or post-accident tests, a canceled result is unacceptable because a verified final result is necessary to comply with regulatory requirements or company policy. Therefore, the employer is required to mandate an immediate re-test, as the original collection did not satisfy the testing requirement.
The MRO communicates the need for a re-collection. Depending on the reason for the initial cancellation, they may require the second collection to be directly observed. This often occurs if the original specimen was canceled due to temperature being out of range or other signs of potential tampering. The re-test must be conducted promptly and without prior notice to the employee to ensure the integrity and accuracy of the new sample. A canceled test is a procedural restart intended to secure a legally valid result.