What is the purpose of Westgard rules in laboratory QC?

What is the purpose of Westgard rules in laboratory QC?

• A. To calibrate instruments before runs.
• B. To interpret run data from control materials and decide whether a run should be accepted, rejected, or investigated.
• C. To set target reference ranges for patient results.
• D. To determine which control materials to use in an assay.

Answer: (B)

Westgard rules are a structured way to judge QC data and decide what to do with a run. They provide a decision framework for interpreting control measurements run alongside patient samples. By plotting control results on a chart and applying predefined criteria, you can tell when performance is still in control or when it’s out of control due to random variation, a shift, or a drift. When the data meet the rules, the run is considered acceptable and patient results can be reported. If the data violate any rule, the run should be investigated, possibly re-run, or stopped to prevent reporting inaccurate results. This approach emphasizes how control data behave over time, rather than calibrating instruments, setting patient reference ranges, or choosing which control materials to use.

Westgard rules are a structured way to judge QC data and decide what to do with a run. They provide a decision framework for interpreting control measurements run alongside patient samples. By plotting control results on a chart and applying predefined criteria, you can tell when performance is still in control or when it’s out of control due to random variation, a shift, or a drift. When the data meet the rules, the run is considered acceptable and patient results can be reported. If the data violate any rule, the run should be investigated, possibly re-run, or stopped to prevent reporting inaccurate results. This approach emphasizes how control data behave over time, rather than calibrating instruments, setting patient reference ranges, or choosing which control materials to use.