Test Not Performed Lab Results: Top 5 Reasons for a No-Test (and How to Prevent Them)

February 13, 2024

The PharmChek® Sweat Patch has provided court-admissable proof of drug use patterns for over 30 years, with the results of our testing method affirmed by judges as reliable, accurate, and secure in multiple cases. But occasionally, a sample can’t be processed, resulting in a Test Not Performed (TNP) lab result.

These no-test results occur when either the sample itself is not adequately supplied or when the standard chain of custody process is not followed properly. When this happens, courts lose out on the evidence they need while incurring additional costs.

Want to avoid the pain of TNPs? Here are the top reasons our customers receive Test Not Performed lab results and how to prevent them.

What Is a Test Not Performed Lab Result?

PharmChek® provides consistently accurate and dependable drug testing results through a standardized sample collection process. Every step, from patch application to lab delivery, is designed to ensure results are court-admissible.

But when one or more of the required criteria for a valid sample isn’t met, that sample can’t be tested. Instead, agencies will receive a Test Not Performed lab result, as well as a no-test fee.

Why a TNP Lab Result?

No one wants to end up without a lab result after a sample is sent. But when drug courts receive results from questionable samples, that evidence could be thrown out. PharmChek®’s sample collection and testing standards help prevent this outcome.

So when a sample arrives at the lab in poor condition or without the proper chain of custody protocols, our lab rejects that sample rather than sending potentially non-defensible results back to agencies.

Top 5 Reasons for Test Not Performed Lab Results

In our 30-plus years of experience, there are really only five problems that cause the majority of Test Not Performed lab results we encounter:

  1. Adhesive on the pads
  2. Insufficient samples
  3. Missing specimen or chain-of-custody form
  4. Altered or mismatched labels
  5. Misapplied labels

TNP First Place: Adhesive on Pads

When trained observers collect the PharmChek® absorbent pad, they must remove all of the adhesive from the pad before sending it in. When that adhesive is still present, the lab can’t run the tests properly without risking contamination.

What To Do:

Trained observers need to carefully remove the adhesive using our standard process, starting with peeling back the top adhesive to expose the pad. Once it is more than 50% exposed, the observer uses the included tweezers to carefully detach the pad from the remaining adhesive before placing it in the specimen bag.

TNP Second Place: Insufficient Samples

If a sample arrives at the lab but is too small, the results may not be accurate. With too little pad to test, the sample must be rejected.

What To Do:

Our lab requires at least 75% of the absorbent pad to avoid a Test Not Performed lab result. The sample does not need to arrive in one piece, but it does need to include enough of the original pad to meet that minimum requirement.

TNP Third Place: Specimen Without COC Form or COC Form Without Specimen

In many cases, the TNP starts with missing components of the sample the lab receives—specifically, either a specimen without a chain-of-custody form or a chain-of-custody form without the specimen.

Senior Account Manager Matthew Hartley explains:

“90 percent of specimens going into DEFNON (eventually reported out as a TNP) are due to receiving a specimen with no COC form. The lab follows a strict process that requires that COC form.”

Likewise, a COC form with no sample can’t return a test result, and agencies instead receive the TNP result.

What To Do:

Before shipping your tests, ensure that each test pad has a coordinated and properly completed COC form and that both are placed in the larger clear transport bag.

TNP Honorable Mention: Mismatched, Altered, or Handwritten Labels

Occasionally, the label/seal number on the specimen bag arrives with alterations that void its reliability. Handwriting a specimen number is one reason our lab won’t accept a sample. While the sample could undergo testing, the TNP lab result has more to do with the potential for tampering in the chain of custody process.

Another common issue we see is that samples arrive with mismatched barcode numbers, where the security seal barcode and the COC barcode don’t match.

What To Do:

The best way to avoid a Test Not Performed result, in these cases, is to ensure the collection materials are coordinated with the PharmChek® chain of custody form. Take extra care in matching specimen labels with the correct patch ID number, so it’s unnecessary to handwrite the correct specimen number over the printed number.

TNP Honorable Mention: Misapplied or Damaged Label

Chain of custody is critical to evidence viability, so we maintain and document a specific process for collecting and sealing the absorbent pad before sending it to the lab. This process includes placing the security seal on the small clear specimen bag correctly.

We frequently encounter misapplied labels, where the label is placed on the larger clear transport bag instead of the smaller clear specimen bag, or labels that have been torn, ripped, or reapplied. The chain of custody can’t be proven in these cases, so the lab rejects the sample and returns a no-test result.

What To Do:

Agencies can avoid these label-related TNPs by reviewing our labeling and transport procedures so labels are placed correctly, eliminating the need to remove and reapply the labels.

How to Eliminate No-Tests

So how can trained observers and agencies avoid no-tests? We have a few simple tools that can bring better clarity to sample collection and transport processes, all of which come at no cost to you.

Online Training

The PharmChek® online training modules (required to become a certified trained observer) provide a thorough step-by-step review of all our standards for patch application, collection, transport, and testing. We also review the basics of patch construction, storage, and wear time to ensure agencies know everything they need to successfully implement sweat-based drug testing in their programs.

Training Tuesdays

Join Kimberly Henderson nearly every Tuesday for in-depth conversations about the PharmChek® Sweat Patch. These free, live, and interactive sessions offer agencies, case managers, and court officials the opportunity to ask questions, discuss challenges with peers, and receive additional training and support directly from PharmChek® experts. We cover many different topics, including sessions dedicated to sample collection and shipping.

Customer Support

Our experienced support specialists are a phone call or email away, bringing their expertise directly to our customers when they need it most. We’ll answer any questions you have, walk you through challenges, and make sure your trained observers, court officials, and case managers can use the PharmChek® Sweat Patch properly to ensure accurate and reliable results every time.