Quality Control in the Laboratory

Quality Control in the Laboratory

• Quality Control (QC) is the process of detecting errors.
• Good quality control provides confidence in clinical data generated by the laboratory.
• Diagnostic testing accounts for 60-70% of medical decision-making.

Internal Quality Control (IQC)

• IQC involves daily monitoring of the precision and accuracy of analytical methods using quality control sera with known values.

External Quality Assessment (EQA)

• EQA compares laboratory performance to other laboratories using sera with unknown concentrations.
• EQA maintains the long-term accuracy of analytical methods.

Quality Assurance

• Quality Assurance (QA) refers to systems or procedures in place to prevent errors from occurring.
• QA and QC work together to ensure the reliability of test results.

Error Classification

• Pre-analytical Errors: Errors occurring before a sample reaches the laboratory.
• Analytical Errors: Errors occurring during the analysis of a sample.
• Post-analytical Errors: Errors occurring after the analysis of a sample.

Types of Pre-Analytical Errors

• Patient preparation: Factors such as fasting, stress, and anxiety can affect test results.
• Sample Collection: Improper collection, hemolysis, insufficient volume, and timing errors can impact results.
• Sample Storage: Leaving samples at room temperature can affect results.
• Unstable analytes require fast handling and analysis.
• Other factors: Age, sex, dietary effects, medical history, pregnancy, drug and alcohol use can all influence results.

Types of Analytical Errors

• Sample handling: Incorrect labeling, processing, or storage.
• Equipment: Improper use, contamination, calibration, and reuse of pipette tips.
• Reagents: Poor quality, expired reagents, improper preparation, incorrect temperature.
• Assay protocol: Incorrect application of assay protocol.
• Instrument use: Operational limitations, maintenance issues, and calculation errors.

Types of Post-Analytical Errors

• Report delivery: Timely and accurate delivery of reports to the correct patient and doctor.
• Data Interpretation: Correct interpretation of results by the doctor.

QC Frequency

• Factors determining QC frequency include the quantity of tests, test risk, staff competency, equipment, reagents, method in use, available time, and assay stability.
• QC is often recommended at the beginning and end of each analytical run or when reagents are changed.
• ISO 15189 regulations recommend that QC materials are examined periodically based on the stability of the procedure and the risk of harm to the patient.
• Laboratories must consider all factors to determine the appropriate QC frequency to ensure confidence in their results.

This quiz covers the essential concepts of quality control, assurance, and error classification in laboratory settings. Dive into internal and external quality control processes that are crucial for reliable diagnostic testing. Learn how effective QC and QA frameworks ensure the accuracy of clinical data.