Behind every DOT drug test is a licensed physician called the Medical Review Officer, or MRO. Many drivers and employers never hear about this step, but it is a required safeguard that protects both sides.
What the MRO Does
The MRO is an independent, licensed physician trained to interpret drug test results. When a lab reports a non-negative result, the MRO reviews it before it is reported to the employer. The MRO verifies the chain of custody, contacts the donor, and asks whether there is a legitimate medical explanation (for example a valid prescription).
Why the MRO Matters
The MRO step prevents a legitimate prescription from being reported as a positive. It also confirms that the lab result is accurate and that the collection was handled correctly. Only after the MRO verifies the result does the employer receive a final, official outcome.
What Happens on a Non-Negative
- The lab flags the specimen and sends it to the MRO
- The MRO attempts to reach the donor to discuss the result
- The donor may provide prescription documentation
- The MRO reports a verified positive or negative to the employer
Frequently Asked Questions
Is an MRO required for every DOT drug test? An MRO must review every non-negative DOT result, and MRO services are a required part of a compliant DOT testing program.
Can the MRO change a positive to a negative? Yes. If the donor provides a valid medical explanation such as a legitimate prescription, the MRO can verify the result as negative.
Does Test Pro provide MRO services? Yes. Our DOT testing program includes MRO review, so every result you receive is physician-verified.
Let Test Pro Handle It
Test Pro LLC in Kent, WA helps owner-operators, motor carriers and employers stay compliant across Washington and beyond — drug and alcohol testing, random pools, IFTA, filings and driver files. Call (206) 518-2097 or book an appointment. Questions first? Contact us.