My Driver Tested Positive and Requested a Split Specimen Retest. Now What?
TRANSPORTATION EMPLOYER COMPLIANCE SERIES
You’ve received a verified positive result from your MRO. Before you could take next steps, your driver contacted the MRO and requested that the split specimen — Bottle B — be sent to a second laboratory for retesting. Now you’re waiting, and you’re not sure what happens next, what you’re required to do, or how likely it is that the result changes.
This is a normal part of the DOT drug testing process. The split specimen retest is a federally protected right under 49 CFR Part 40, and understanding how it works — and what your obligations are while it’s pending — will help you manage the situation correctly.
What Is the Split Specimen Process?
Every DOT-regulated urine collection produces two specimens from a single void: Bottle A (the primary specimen) and Bottle B (the split specimen). Both bottles are sealed and sent to the primary laboratory at the time of collection. Bottle A is tested; Bottle B is kept frozen and held in reserve.
When the primary lab returns a non-negative result and the MRO issues a verified positive, the driver has the right under 49 CFR Part 40.171 to request that Bottle B be shipped to a second DHHS-certified laboratory for independent confirmation testing. This request must be made within 72 hours of the driver being notified of the verified positive by the MRO.
The split specimen process is not an appeal. It is not a challenge to the MRO’s medical judgment. It is a scientific retest of the same collection — a second laboratory testing the second bottle to confirm or contradict what the first laboratory found.
| The split specimen request is a federally protected right. Employers cannot discourage, delay, or penalize a driver for exercising it. |
The Process Step by Step
Here is how the split specimen process unfolds under 49 CFR Part 40, from verified positive to final result:
| Step | Who Acts | Timeframe | Regulatory Basis |
|---|---|---|---|
| MRO reports verified positive to employer | MRO | Before driver is notified | 49 CFR Part 40.163 |
| MRO informs driver of right to request Bottle B test | MRO | At time of verified positive notification | 49 CFR Part 40.170 |
| Driver requests split specimen retest | Driver | Within 72 hours of MRO notification | 49 CFR Part 40.171 |
| Driver arranges payment for retest | Driver | Before retest is initiated | 49 CFR Part 40.173 |
| MRO directs primary lab to ship Bottle B to secondary lab | MRO | Promptly after payment confirmed | 49 CFR Part 40.175 |
| Secondary lab tests Bottle B | Secondary lab | No regulatory deadline; typically 3–5 business days | 49 CFR Part 40.177 |
| Secondary lab reports result to MRO | Secondary lab | Upon completion | 49 CFR Part 40.179 |
| MRO issues final verified result to employer | MRO | Upon receipt of Bottle B result | 49 CFR Part 40.187 |
The 72-hour window runs from when the MRO notifies the driver — not from when the employer receives the result. The MRO is required to inform the driver of the split specimen right at the time of notification, and to provide the name of the laboratory that tested Bottle A.
Who Pays for the Retest?
Under 49 CFR Part 40.173, if the driver cannot pay for the split specimen retest, the employer must ensure the cost is covered so the process moves forward without delay. The employer may seek reimbursement from the driver afterward.
However, if the split specimen retest returns a result that cancels the original positive — either a negative result or an untestable specimen — and the employer has a policy or agreement that addresses reimbursement in that scenario, that is a separate employment matter between the employer and driver. The regulation itself places the cost on the driver regardless of outcome.
What Are You Required to Do While the Retest Is Pending?
This is where employers most commonly make mistakes. Under 49 CFR Part 382.305 and Part 40.191, a verified positive result requires immediate removal from safety-sensitive functions. That obligation does not pause while the split specimen retest is pending.
The driver must be removed from safety-sensitive duty — driving a CDL vehicle — as soon as the verified positive is reported. The split specimen request does not suspend that requirement. The driver remains out of safety-sensitive functions until the split specimen result is reported and the MRO issues a final determination.
| A pending split specimen request does not allow the driver to continue driving. Removal from safety-sensitive duty is required immediately upon the verified positive — and stays in effect until the MRO closes the process. |
Do not allow the driver to return to a CDL seat while Bottle B is being tested. If the split specimen ultimately cancels the result, the driver can return at that point. But operating a CDL vehicle on a pending positive — regardless of the driver’s confidence in the outcome — creates significant liability for the employer.
What Are the Possible Outcomes?
When the secondary laboratory reports its finding to the MRO, there are several possible outcomes, each with different consequences:
| Bottle B Result | MRO Final Report | Effect on Employer Action |
|---|---|---|
| Confirmed positive for same substance | Verified positive stands | No change — removal from safety-sensitive duty remains in effect |
| Negative | MRO cancels the test | Employer must reinstate driver; test is treated as if it never occurred |
| Bottle B insufficient / untestable | MRO cancels the test | Employer must reinstate driver; no action can be taken on the cancelled result |
| Bottle B confirms different substance | MRO reports only confirmed substance | Verified positive for confirmed substance only |
The most important outcome to understand is the cancelled test scenario. If Bottle B comes back negative, or if it cannot be tested due to insufficient volume or other integrity issues, the MRO is required to cancel the entire test under 49 CFR Part 40.187. A cancelled test is not a negative — it carries no result at all. The employer cannot treat it as a positive, cannot use it in a SAP referral, and must allow the driver to return to safety-sensitive duty.
In practice, split specimen retests that cancel the original positive are uncommon. When the primary laboratory’s finding is confirmed by the secondary laboratory in the large majority of cases, the verified positive stands. But the process exists precisely because laboratory error, chain-of-custody issues, and specimen integrity problems can and do occur — and a driver’s career should not end on a result that a second test would have contradicted.
What If the Driver Misses the 72-Hour Window?
If the driver does not request the split specimen retest within 72 hours of MRO notification, the right to request it is forfeited. The MRO’s verified positive stands as the final result, and the employer proceeds with the consequences of a confirmed positive: the driver must complete a SAP evaluation, cannot return to safety-sensitive duty until all return-to-duty requirements are met, and is subject to follow-up testing upon reinstatement.
Under 49 CFR Part 40.171, the MRO has discretion to honor a late request if the driver provides a legitimate explanation for missing the window — documented illness, for example. But this is the MRO’s call, not the employer’s, and it is not guaranteed.
Practical Guidance for Employers
When your driver requests a split specimen retest, the right approach is straightforward:
- Keep the driver out of safety-sensitive functions. Do not allow driving pending the outcome.
- Do not interfere with the process. The split specimen right belongs to the driver, and the MRO manages it. Your role is to wait for the MRO’s final determination.
- Document the timeline. Note when you received the verified positive, when you removed the driver from duty, and when you were notified of the split specimen request.
- Do not initiate the SAP referral process until the MRO issues a final result. If the test is ultimately cancelled, a SAP referral based on that test would have no regulatory basis.
- Be prepared for either outcome. Have a plan for reinstatement if the result is cancelled, and have your SAP referral process ready if the positive is confirmed.
| The split specimen process is designed to protect both the driver and the integrity of the testing program. A well-run employer program treats it as exactly that — not as an obstacle, and not as a reason to delay acting on a confirmed positive. |
TrueTest Labs Can Walk You Through It
A verified positive and a split specimen request involve multiple moving parts — the MRO, two laboratories, regulatory deadlines, and employment decisions that carry real consequences. TrueTest Labs works with transportation employers to make sure the process is handled correctly at every step, from initial result notification through final MRO determination.
If your driver has requested a split specimen retest and you have questions about your obligations, contact us at mgammel@truetestlabs.com or visit truetestlabs.com.
TrueTest Labs | Elk Grove Village, Illinois | truetestlabs.com | mgammel@truetestlabs.com