35 Year 3: Chemical Pathology exam questions on Chemical Pathology for medical students. Includes MCQs, answers, explanations and written questions. Sample: The
This MCQ set contains 35 questions on Chemical Pathology in the Year 3: Chemical Pathology unit. Each question includes the correct answer and a detailed explanation for active recall and exam preparation.
Correct answer: B – QA is broader and encompasses QC
Quality Assurance (QA) is a comprehensive approach that encompasses all aspects of laboratory operations including policies, procedures, training, and compliance. Quality Control (Q
Correct answer: B – Levey-Jennings charts
Levey-Jennings charts are the most common tool used in clinical chemistry QC to plot control sample results over time. They help visualize variations and trends in test performance and are used with Westgard rules for interpretation.
Correct answer: C – Proper storage temperature and transport time
The pre-analytical phase occurs before sample analysis. Proper storage temperature and timely transport are crucial to prevent sample degradation, hemolysis, or analyte instability, which can significantly impact test accuracy.
Correct answer: B – Verify that the test method can detect the analyte correctly
Positive controls contain known concentrations of the analyte and are used to verify that the test method is functioning properly and can accurately detect the analyte at expected levels.
Correct answer: B – Westgard rules
Westgard rules are specific statistical rules applied to QC control chart data to identify acceptable performance and signal potential analytical problems. These rules help determine when corrective action is needed.
Correct answer: B – Compare laboratory performance with other labs or reference values
EQA involves proficiency testing where laboratories analyze the same samples and compare results with other laboratories or established reference values. This helps identify issues with analytical procedures and provides opportunities for improvement.
Correct answer: C – Instrument calibration and test performance monitoring
The analytical phase involves the actual testing process, including instrument calibration, maintenance, running control samples, and monitoring test performance to ensure accurate measurements.
Correct answer: B – Calibration and method validation with well-documented values
CRMs are materials with well-documented and certified values that serve as benchmarks for calibration of analytical methods and validation of test procedures, ensuring traceability to recognized standards.
Correct answer: C – Pre-analytical phase
Studies consistently show that 60-70% of laboratory errors occur in the pre-analytical phase, involving issues with sample collection, handling, transport, and processing before the actual analysis begins.
Correct answer: C – Custom-prepared using the laboratory's own methods and materials
In-house controls are prepared by the laboratory using their own methods and materials, allowing customization for specific needs, while commercial controls are pre-prepared solutions purchased from suppliers.
Correct answer: B – Test volume, variability, and criticality
QC frequency is determined by multiple factors including the test's volume and frequency, method stability, analytical variability, and clinical criticality of the results. High-volume or critical tests may require more frequent QC monitoring.
Correct answer: B – Assess performance across different analyte concentration ranges
Multi-level controls contain different concentrations (low, normal, high) of analytes to assess method performance across the entire analytical range, ensuring accuracy at all clinically relevant levels.
Correct answer: B – Highly pure substances used to prepare calibration solutions
Primary standards are highly pure substances with known compositions used to prepare calibration solutions with precise, known concentrations. They serve as the fundamental reference for analytical measurements.
Correct answer: C – Sample centrifugation
Sample centrifugation occurs in the pre-analytical phase during sample processing. The post-analytical phase involves activities after test results are generated, including validation, reporting, and data management.
Correct answer: B – Provide unbiased evaluation of laboratory performance
Blind samples are sent to laboratories without prior knowledge of their content, ensuring unbiased testing and evaluation of true laboratory performance without preconceived expectations affecting results.
Correct answer: B – Clinical and Laboratory Standards Institute (CLSI)
CLSI develops and publishes standards and guidelines for clinical laboratory testing, including quality control procedures. Other important bodies include CAP (College of American Pathologists) and ISO.
Correct answer: B – Prevent failures and ensure consistent performance
Routine maintenance prevents equipment failures, ensures consistent analytical performance, extends instrument life, and maintains the reliability and accuracy of test results over time.
Correct answer: B – Precision only
The coefficient of variation (CV) measures the relative standard deviation and is used to assess precision (reproducibility) of analytical methods. Accuracy is assessed by comparing results to known true values.
Correct answer: A – Identifying and mitigating potential risks to testing quality
Risk management in QA involves systematically identifying potential risks that could affect the quality of laboratory testing and implementing strategies to mitigate or eliminate these risks.
Correct answer: A – Ensure consistency and standardization in laboratory processes
SOPs provide detailed, standardized procedures for all laboratory processes, ensuring consistency across different operators and shifts, reducing variability, and maintaining quality standards.
Correct answer: B – Relate instrument response to analyte concentration
Calibration curves establish the mathematical relationship between instrument response (signal) and analyte concentration, enabling accurate quantitative measurement of unknown samples.
Correct answer: B – Assess compliance and identify improvement areas
Internal audits systematically evaluate laboratory compliance with QA procedures, identify areas for improvement, and ensure adherence to regulatory requirements before external inspections.
Correct answer: B – Proper identification to prevent mix-ups
Proper sample labeling with unique patient identifiers is crucial to prevent sample mix-ups, which can lead to incorrect results being reported to the wrong patients, potentially causing serious clinical consequences.
Correct answer: C – Shelf-life and stability of reagents and controls
Stability testing determines how long reagents, controls, and samples remain stable and effective under various storage conditions, helping establish appropriate expiration dates and storage protocols.
Correct answer: B – Periodic evaluation of staff proficiency and adherence to protocols
Competency assessment regularly evaluates staff abilities to perform procedures correctly and consistently, ensuring they maintain proficiency and follow established protocols throughout their employment.