Medical Laboratory Technician Exam Medical Laboratory Technician Laboratory Operations and QC 1

Question 1

A QC chart shows seven consecutive control values all falling on the same side of the mean. Which Westgard rule does this pattern violate?

Accepted Answer

10x rule

Answer

The 10x rule is triggered when ten consecutive control measurements fall on the same side of the mean, indicating a systematic shift or bias in the method. Seven consecutive points on one side is an early warning of the same trend, and the 10x rule specifically addresses this systematic error pattern.

Question 2

Which of the following best describes the chain of custody in a laboratory setting?

Accepted Answer

A record documenting every individual who handled a specimen from collection to final disposal

Answer

Chain of custody is the documented record tracking every person who collected, transferred, received, or tested a specimen. It is essential in medicolegal cases to ensure specimen integrity and admissibility of results in legal proceedings.

Question 3

A technician notices that a reagent bottle has been open for three weeks, but the manufacturer's stability after opening is listed as two weeks. What is the most appropriate action?

Accepted Answer

Discard the reagent and open a new bottle

Answer

Reagents used beyond their open-vial stability period must be discarded regardless of current QC performance, because degradation may not yet be detectable but can compromise result accuracy. Following manufacturer guidelines for stability is a fundamental QC principle.

Question 4

What is the purpose of a calibration verification procedure in the clinical laboratory?

Accepted Answer

To confirm that the measuring system can accurately reproduce results across its reportable range

Answer

Calibration verification confirms that a calibrated instrument continues to accurately report patient values across its entire analytical measurement range (AMR). It is required at defined intervals and whenever calibration is performed, a major maintenance event occurs, or QC repeatedly fails.

Question 5

Which of the following is an example of a pre-analytical error?

Accepted Answer

A blood sample collected in the wrong tube type for the ordered test

Answer

Pre-analytical errors occur before the specimen enters the testing phase and include mistakes in collection, labeling, transport, or tube selection. Using the wrong anticoagulant tube can falsely alter test results, making this a classic pre-analytical error.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Medical Laboratory Technician Laboratory Operations and QC 1