Medical Laboratory Technician Laboratory Operations and QC Questions and Answers

Question 1

An MLT reviewing a Levey-Jennings chart for a daily glucose control run notices that the last two consecutive data points are outside the +2 SD limit. Which Westgard rule has been violated?

Accepted Answer

2_2s

Answer

The 2_2s rule is violated when two consecutive control values fall on the same side of the mean and are beyond 2 standard deviations (+2s or -2s). This is a rejection rule that indicates a systematic error in the testing process.

Question 2

A phlebotomist collects specimens for coagulation studies (light blue top), a complete blood count (lavender top), and a chemistry panel (serum separator tube - SST). If the tubes are drawn in the order of SST, lavender, and then light blue, which test result will most likely be falsely elevated?

Accepted Answer

Prothrombin Time

Answer

The correct order of draw is critical to prevent additive cross-contamination. The lavender top tube contains EDTA, a potent anticoagulant that works by chelating calcium. If the lavender tube is drawn before the light blue (sodium citrate) tube, trace amounts of EDTA can be carried over into the citrate tube. This contamination will chelate the calcium in the sample, which is essential for the coagulation cascade, leading to a falsely prolonged (elevated) Prothrombin Time (PT) and aPTT.

Question 3

To find comprehensive information regarding the hazards, safe handling, and emergency procedures for a new chemical reagent, an MLT should primarily consult the:

Accepted Answer

Safety Data Sheet (SDS)

Answer

The Safety Data Sheet (SDS), formerly MSDS, is a document mandated by OSHA that provides detailed information about a hazardous chemical. It includes properties, health hazards, protective measures, and safety precautions for handling, storing, and emergency response.

Question 4

A laboratory is validating the precision of a new assay. A control material is analyzed 20 times, yielding a mean value of 80 mg/dL and a standard deviation (SD) of 4 mg/dL. What is the coefficient of variation (CV)?

Accepted Answer

5.0%

Answer

The coefficient of variation (CV) is a measure of relative variability. The formula is CV (%) = (Standard Deviation / Mean) × 100. For this data: (4 mg/dL / 80 mg/dL) × 100 = 5.0%.

Question 5

Under the Clinical Laboratory Improvement Amendments (CLIA), which of the following is a key requirement for laboratories performing moderate and high-complexity testing but NOT for those performing only waived testing?

Accepted Answer

Successful participation in an external proficiency testing (PT) program.

Answer

CLIA regulations require laboratories performing moderate and high-complexity tests to enroll and participate successfully in an approved external proficiency testing (PT) program. PT is used to verify the accuracy and reliability of a laboratory's testing. Laboratories that perform only waived tests are not required to participate in PT, although they must follow manufacturer's instructions.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Laboratory Operations and QC Questions and Answers