Laboratory Operations and Quality
Quality systems and statistical control
Laboratory operations questions test the difference between quality control, calibration, and proficiency testing. Calibration establishes the analyzer's response curve; QC monitors ongoing performance; proficiency testing evaluates the laboratory against peers. Levey-Jennings charts display QC values around the mean, and Westgard rules flag random or systematic error. 1_2s is usually a warning; 1_3s, 2_2s, R_4s, 4_1s, and 10x indicate rejection or investigation depending on the laboratory's validated policy. Document corrective action, root cause, and patient impact. Patient identification, specimen labeling, critical-value reporting, delta checks, and turnaround time are pre- and postanalytical quality indicators. Biosafety and chemical hygiene require risk assessment, PPE, engineering controls, and spill response. Competency assessment is ongoing, not a one-time checklist.
Traps and worked rule
A common trap is treating a 1_2s QC flag as automatic rejection; another is using a new lot of reagent without calibration/verification or ignoring a shift on the Levey-Jennings chart. Worked rule: when one QC level exceeds 1_3s, stop, repeat the control, check reagent and calibration, and do not report patient results until acceptability is documented. Rule of thumb: QC failures are investigated before results are released; proficiency-testing failures trigger corrective action, not result deletion alone.