Medical Review Officers

Short Answer

A Medical Review Officer (MRO) is a licensed physician responsible for receiving laboratory drug test results, reviewing them, and making a final determination about whether a result is verified positive, negative, cancelled, refusal to test, or another outcome recognized under Part 40. The MRO is the safeguard between a laboratory's technical result and the record that reaches the employer. This article is a quick reference entry point. For a full explanation of the MRO's role, see What Does a Medical Review Officer Do?

Key Facts About the MRO Role

Definition: A licensed physician responsible for receiving and reviewing laboratory drug test results and evaluating medical explanations for certain results.
Reviewing Refusals to Test: Certain events, such as an employee failing to cooperate with the collection process or admitting to adulterating a specimen, are treated as a refusal to test. The MRO's review process intersects with these determinations.
Handling Insufficient Specimens: When an employee cannot provide a sufficient urine or oral fluid specimen, the DER, after consulting the MRO, directs the employee to a medical evaluation to determine whether a medical condition explains the failure. The MRO's consultation is part of that process.
Cancelling Tests for Fatal Flaws: The MRO cancels a test when the laboratory reports an invalid result, a rejected specimen, or certain split specimen problems, among other fatal flaws that require cancellation regardless of the specimen's testing outcome.
Correcting Fixable Problems: Some paperwork problems, such as a missing collector or employee signature on the Custody and Control Form, can be corrected without cancelling the test. The MRO's office is involved in confirming whether a correctable flaw was actually corrected.

Applicable Regulations

Professional Observation

In my experience, employees often assume the laboratory makes the final call on a drug test result. It does not. The laboratory reports a technical finding, and the MRO applies medical and regulatory judgment before that finding becomes a verified result. Understanding this distinction matters most when an employee has a legitimate medical explanation to offer, since that explanation is reviewed by the MRO, not the lab.

Primary Authorities

Have a Question About Your MRO Review?

If you are waiting on an MRO determination or have a medical explanation to submit, a DOT qualified Substance Abuse Professional can help you understand the process.

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