Quality Control in Clinical Laboratory

Your Guide to Ensuring Accuracy and Reliability in Lab Results

Discover how Quality Control (QC) safeguards clinical laboratory testing

What is Quality Control in Clinical Laboratories?

Quality Control (QC)(ISO 15189:2022) in clinical laboratories refers to the systematic processes used to ensure the accuracy, precision, and reliability of diagnostic test results. It involves monitoring and verifying the performance of laboratory instruments, reagents, and procedures to detect and correct errors.

QC is essential to maintain high standards in patient care, as inaccurate results can lead to misdiagnosis or improper treatment.

Example: A lab testing cholesterol levels uses QC samples to confirm that the analyzer is functioning correctly. If the QC sample result deviates significantly, the lab investigates before reporting patient results.

Key QC Procedures

Clinical laboratories implement several QC measures, including:

Control Samples: Running known samples with expected results alongside patient samples to verify instrument accuracy.
Calibration: Regularly calibrating equipment to ensure consistent performance.
Levey-Jennings Charts: Plotting QC data to monitor trends and detect deviations.
Westgard Rules: Applying statistical rules to identify systematic or random errors in QC data.
Proficiency Testing: Participating in external programs to compare results with other labs.

Figure 1: Levey-Jennings Chart Example - This chart plots glucose control sample results (mean: 100 mg/dL, SD: 3 mg/dL) over 5 runs, showing a trend within acceptable limits (±2SD).

Why QC Matters

Effective QC ensures:

Patient Safety: Accurate results lead to correct diagnoses and treatments.
Regulatory Compliance: Labs must meet standards set by organizations like CLIA and CAP.
Cost Efficiency: Early detection of errors reduces the need for retesting.
Trust: Reliable results build confidence among healthcare providers and patients.

By prioritizing QC, clinical laboratories uphold their commitment to excellence in healthcare.