When we think about diagnostic testing, we tend to expect a straightforward answer: positive or negative. But sometimes a result is neither. An inconclusive result means that the test has not provided enough information to confidently confirm or rule out a particular condition.
For patients, this can be frustrating and unsettling, particularly when they are expecting a clear answer. For those developing, validating and delivering diagnostic tests, it highlights an important point: a reliable result depends on much more than the test itself.
Why can a test result be inconclusive?
There are several reasons why a diagnostic test may not produce a clear result.
The sample may not be suitable: The amount or quality of a sample can affect whether a test can detect what it is looking for. Issues with collection, handling or storage can also influence the result.
Timing can matter: Some conditions or biomarkers change over time. Testing too early, for example, may mean there is not enough of the target to produce a definitive result.
The result may sit close to a threshold: Many diagnostic tests use defined cut-offs to determine whether a result is positive or negative. Results close to that boundary can be more difficult to interpret with confidence.
Testing processes can introduce variability: Laboratory procedures, equipment, reagents and other factors can all contribute to variation in results, which is why robust processes and quality controls are important.
An inconclusive result does not necessarily mean something has gone wrong. It can simply reflect the limitations of what that particular sample and test combination can tell us at that point in time.
What happens after an inconclusive result?
The next step will depend on the test, the clinical situation and why the result was inconclusive.
A repeat test may provide a clearer answer, particularly if there were concerns about the original sample or the timing of testing. In other cases, a different test or additional clinical information may be needed to build a more complete picture.
This is where interpretation becomes particularly important. A diagnostic result should not always be viewed in isolation; it needs to be considered alongside the quality of the sample, the circumstances in which the test was performed and the wider clinical context.
Reliable diagnostics depend on the whole testing pathway
For developers, laboratories and healthcare professionals, an inconclusive result is a reminder that reliable diagnostics depend on the whole testing pathway – from sample collection to final interpretation.
A test may demonstrate strong analytical performance, but that is only one part of the picture. The quality and handling of the sample, the conditions in which the test is performed, the processes supporting it and how the result is ultimately interpreted can all influence the outcome.
This is why diagnostic development and validation need to look beyond whether a test can detect a particular target under controlled conditions. Understanding how it performs in its intended setting – and where uncertainty or variability may arise – is equally important.
Clear instructions for use, appropriate quality controls and defined approaches for handling inconclusive results can help ensure that uncertainty is recognised and managed rather than overlooked.
For patients, an inconclusive result can mean waiting longer for an answer. For those responsible for developing and delivering diagnostics, it is a useful reminder that the reliability of a result is built across the entire testing pathway, not just at the point where the result is produced.
Back to News + Insights