Section C

Tests & Diagnostic Pathways

What tests are for, how they are read, and where they fall short.

A useful test begins with a clear question about what information is needed and how it could affect care.

Screening, diagnosis and monitoring ask different questions and require evidence suited to their intended use.

A laboratory result depends on a connected process of collection, identification, transport, processing and reporting.

Preparation, collection and handling can change a sample before laboratory measurement begins.

Laboratory methods measure different features of a sample, each with its own strengths and limits.

Imaging methods use different physical signals to answer questions about body structure or function.

Examining cells and tissue can reveal patterns that help identify disease and guide its classification.

Biomarkers are measurable characteristics that can provide different kinds of information about biological processes or responses.

Reference intervals describe results in a selected population, while decision thresholds help guide particular clinical decisions.

Sensitivity and specificity describe how a test classifies people with and without a defined condition.

The meaning of a positive or negative result depends partly on how likely the condition was before testing.

Results may remain uncertain or disagree because of biological differences, timing, sampling or limitations in the testing methods.

Follow-up combines test findings with symptoms, prior evidence and the remaining uncertainty to determine what happens next.