18 Questions
What type of errors occur during sample collection, transport, or processing prior to the analysis step?
Preanalytical errors
Which of the following is an example of a preanalytical error related to specimen collection?
Specimen mislabeled
When do postanalytical errors occur?
After the analysis has taken place
Which type of error may involve issues like interfering substances present and not recognized or bubbles or particles in the sample?
Analytical errors
What could be a consequence of a preanalytical error related to a patient being improperly prepared?
Specimen collected in wrong container
Which error category involves issues like the result reported incorrectly or with inappropriate units of measure?
Postanalytical errors
What is one negative consequence of particulate matter, like microclots, in a plasma sample?
Impedes the measurement by clogging the sampling probe
Which error is likely to occur if a laboratory uses less than the required volume of patient specimen in the reaction mixture?
Analytical error
In the context of automation in laboratories, what does 'Reference Range' refer to?
The range of values considered normal for a particular test
How does automation impact the modern laboratory's efficiency and capacity?
Increases efficiency and capacity by automating manual steps
Which phase of the analytical process involves controlled operation by mechanical or electronic devices without human intervention?
Analytical phase
'Short sampling' in laboratory procedures can lead to which type of error?
Random error
What are the three most common interferents in a serum or plasma sample?
Hemoglobin, Icteric (or Bilirubin), Lipemia
Which condition is characterized by the presence of extremely high triglycerides making the sample turbid?
Lipemic
What is the term used to refer to samples with high bilirubin content?
Icteric
What type of errors occur as a result of unpredictable events that affect the measurement of the signal?
Random errors
Which of the following examples represents a random error in laboratory testing?
Air bubbles in the sample leading to an incorrect volume measurement
How can a bubble in the light path of a spectrophotometer affect test results?
Lead to underestimation or overestimation of analyte concentration
Study Notes
Sources of Error
- Sources of error are typically divided into three categories: preanalytical, analytical, and postanalytical.
Preanalytical Errors
- Occur during sample collection, transport, or processing prior to analysis
- Examples:
- Wrong test ordered
- Test order misunderstood
- Patient improperly prepared or misidentified
- Specimen collected in wrong container or with incorrect additive
- Inadequate amount of specimen collected
- Specimen transport under improper conditions
- Delay in processing and transport time
Analytical Errors
- Occur during analysis
- Examples:
- Instrument not calibrated correctly
- Interfering substances present and not recognized
- Dilution error
- Bubbles or particles present in sample
- Hemoglobin, Icterus (Bilirubin), and Lipemia are common interferents in serum or plasma samples
Postanalytical Errors
- Occur after analysis
- Examples:
- Result reported incorrectly or with inappropriate units of measure
- Result sent to wrong location
- Report delayed or incomplete
Random Errors
- Errors that occur due to unpredictable events affecting the measurement of the signal
- Examples:
- Air bubbles or particulate matter in the sample
- Pipetting a too-small volume of sample
- Particulate matter (e.g., microclots) in a plasma sample
Automation
- Defined as the mechanization of steps in procedures or the use of machines to follow a predetermined sequence of individual operations with minimal human involvement
- The modern laboratory uses a high degree of automation, allowing operators to focus on tasks that cannot be readily automated
- Automation is applied to the analytical process, which can be divided into three phases: preanalytical, analytical, and postanalytical
Learn about precision, accuracy, and bias in laboratory analysis. Explore the three divisions of error sources: preanalytical, analytical, and postanalytical. Test your knowledge on common errors that can occur during sample collection, analysis, and post-analysis stages.
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