What condition leads to a rejection of the run according to the R4s rule?

The condition that leads to a rejection of the run according to the R4s rule is when both controls exceed a mean value of +2 standard deviations (SD). This rule is part of process control in laboratory settings, specifically for quality assurance.

When both control samples are outside the +2SD limit, it indicates that there may be a systematic error or an underlying issue with the analytical process. In a controlled process, results are expected to fall within ±2SD from the mean in a normal distribution. If both control results are beyond this threshold, it suggests that the analytical method is not functioning properly, and the run of tests should be rejected to ensure patient safety and accurate results.

This rule is pivotal in maintaining the integrity of test results. By adhering to it, laboratories can prevent the reporting of erroneous results that could adversely affect patient care. Understanding this helps laboratory managers and technologists ensure that processes remain reliable and consistent.

The other options deal with different scenarios that do not require immediate rejection of the run or describe acceptable ranges for control results. Therefore, the specific situation of both controls exceeding +2SD is the most critical for rejection in accordance with the R4s rule.