Phlebotomy Test Quality Assurance and Quality Control 2

Question 1

Which of the following BEST describes the purpose of a quality assurance (QA) program in a laboratory?

Accepted Answer

To monitor and improve all processes affecting the quality and accuracy of patient test results

Answer

QA encompasses the entire system of monitoring, evaluating, and improving all laboratory processes—pre-analytical, analytical, and post-analytical—to ensure accurate, reliable results.

Question 2

A QC control value plots at +2.3SD on the Levey-Jennings chart. According to Westgard rules, this result is:

Accepted Answer

A warning (1₂s violation)—investigate before running patient samples

Answer

A value between ±2SD and ±3SD triggers the 1₂s warning rule—not an automatic rejection, but a signal to investigate before proceeding with patient testing.

Question 3

A laboratory is investigating a systematic positive bias in sodium results compared to proficiency testing. Which of the following is MOST likely to be the cause?

Accepted Answer

Calibrator drift or incorrect calibration assignment

Answer

Systematic bias (consistently too high) in an electrolyte analyzer most commonly results from calibrator drift, where the reference solution's concentration has shifted, causing all results to be offset.

Question 4

Proficiency testing (PT) is an EXTERNAL quality assessment tool that primarily evaluates:

Accepted Answer

The accuracy of a laboratory's test methods by comparing results with peer laboratories

Answer

Proficiency testing sends unknown specimens to a laboratory and compares its results against peer laboratory results and target values to assess method accuracy.

Question 5

A laboratory QA review finds that the specimen rejection rate for hemolysis has increased from 2% to 8% over the past month. The FIRST step in the quality improvement process is to:

Accepted Answer

Investigate the root cause by analyzing rejection data by phlebotomist, time of day, and patient unit

Answer

Root cause analysis must precede intervention—the rejection rate data must be stratified to identify where and why the increase is occurring before choosing the appropriate corrective action.

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Phlebotomy Test Quality Assurance and Quality Control 2