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Drug Test Results Explained: Negative, Positive, Pending, Dilute

A lab drug test result goes through two stages. First the lab reports what it found. Then, for any result that isn't a plain negative, a medical review officer (MRO) reviews it and decides the final result. The words you see, such as pending, non-negative, dilute or cancelled, depend on which stage the test is in. This guide explains each term for a lab urine test like Pact's $40 10-panel. For how long each step takes, see our guide to how long drug test results take.

Updated October 24, 2026 · Checked against the official sources listed at the end

Two stages: the lab result and the verified result

Quest tests urine in two tiers. A screen on one portion sorts out negatives. A specimen that isn't negative is confirmed on a different portion with a more specific test. Quest says negative screens are often released within 24 hours, and non-negative screens typically take an additional 24 to 72 hours.

Federal DOT rules give the clearest public definitions of each result. They don't govern Pact's non-DOT test, but the terms are widely used. Under 49 CFR 40.97, a DOT lab reports results only to the MRO. Under 40.129, the MRO then verifies a non-negative lab result as negative, cancelled, or positive or a refusal to test. On Pact's 10-panel, a lab result that isn't negative goes to the MRO, who contacts the person tested about prescriptions before the result is final.

Negative

No drug on the panel was found at or above its cutoff. It doesn't mean the level was zero. Below the cutoff, the lab reports negative. Quest says negative results are often released within 24 hours after the specimen reaches its lab.

Pending, in process or non-negative

These words mean the result isn't final yet. A test can be waiting for several reasons:

The specimen is still on its way to the lab.
The screen wasn't negative, so the lab is running the confirmation test.
The lab has reported to the MRO, and the MRO is reviewing it or trying to reach you.
A "non-negative" screen is not a positive. Federal guidance notes that screening tests can react to things other than the target drug, and confirmation sorts that out.

Positive

At the lab, positive means the confirmation test found the drug at or above the confirmation cutoff. That is the lab's finding, not the final result. Under DOT rules, the MRO must give the person a chance to explain, such as with a valid prescription. If there is a legitimate medical explanation, the MRO verifies the test as negative (40.137). If not, it is verified positive. Our guide on why an MRO may call you explains that conversation.

Negative-dilute and positive-dilute

Dilute means the urine was more watery than normal, based on its creatinine and specific gravity (40.88). A negative-dilute found no drugs at or above the cutoffs. A positive-dilute found a drug anyway, and under DOT rules it is treated as a verified positive (40.197(a)). For non-DOT tests, the employer's policy decides whether a negative-dilute needs a retest. Our guide to negative-dilute results covers the details.

Invalid, adulterated and substituted

Invalid: something in the specimen kept the lab from getting a valid result. Quest says all invalid results are automatically tested twice. Under DOT rules, the MRO asks about medicines and may cancel the test and order a new collection (40.159).
Adulterated: a substance was found that isn't normally in urine, or a normal substance was at an abnormal level. Quest uses this definition from federal guidelines.
Substituted: creatinine and specific gravity so far off that the specimen isn't consistent with human urine (40.88(b)). Under DOT rules, the MRO reports adulterated and substituted results as a refusal to test (40.129(f)).

Cancelled and rejected

Cancelled means the test doesn't count as either a negative or a positive. Under DOT rules, the MRO may cancel a test for an invalid result or for certain errors on the custody form (40.129 and 40.159). For an invalid result, DOT rules say a new test is needed when a negative result is required, such as before hire.

Rejected for testing means the lab didn't test the specimen and reports why (40.97). In both cases, the employer or program will tell you whether you need a new test. On a Pact order, call Pact before you order again.

Who sees your result, and who to ask

On a Pact order, the result is reported to the person tested and to the employer or program named at checkout. Quest says that once the test is done, it can't give information about specimen status or the result. So don't call the collection site. Ask whoever ordered the test. For a Pact order, call Pact at 901-666-6970.

Common questions

What does a pending drug test mean?

The result isn't final yet. The specimen may still be in transit, in confirmation testing at the lab, or with the medical review officer. A longer wait alone doesn't tell you the result.

Does non-negative mean I failed?

No. A non-negative screen goes on to a confirmation test, and any confirmed result goes to the MRO before it's final. Screens can react to other substances.

Is a negative-dilute a pass?

No drugs were found at or above the cutoffs. Whether a new test is needed depends on the employer's policy, or on DOT rules for DOT tests.

Can the collection site tell me my result?

No. Quest says it can't give specimen status or results after the test. Ask whoever ordered it. For a Pact order, contact Pact.

What does refusal to test mean on a drug test?

Under DOT rules, the MRO reports an adulterated or substituted specimen as a refusal to test (49 CFR 40.129(f)). Your employer or program will tell you what their policy does with that result.

What happens after a positive lab result?

The MRO contacts you to ask about prescriptions or other medical explanations before the result is final. Answer calls from unknown numbers and have your prescription details ready.