CSMLS Laboratory Safety and QA Questions and Answers — Questions and Answers
Question 1: A medical laboratory technologist spills approximately 10 mL of 1 Molar hydrochloric acid on a countertop. Which of the following is the most appropriate initial action?
- Wipe the spill immediately with absorbent paper towels.
- Evacuate the laboratory and call the emergency response team.
- Cover and neutralize the spill with sodium bicarbonate powder. (Correct answer)
- Consult the Safety Data Sheet (SDS) before taking any action.
Correct answer: Cover and neutralize the spill with sodium bicarbonate powder.
For a small, manageable acid spill, the primary immediate action is to neutralize it. Sodium bicarbonate is a weak base commonly used for this purpose, which safely neutralizes the acid before cleanup. [2, 4] Wiping with paper towels alone could spread the corrosive chemical and risk skin contact. Evacuation is unnecessary for a minor spill, and while consulting the SDS is important for understanding all hazards, the immediate neutralization of a known common acid is the standard first step. [20]
Question 2: A laboratory is implementing a new automated immunoassay analyzer. To verify the new method's performance, the lab sends 50 patient samples to a reference laboratory that uses the established 'gold standard' method. The results from both analyzers are then compared. This process is primarily assessing which of the following performance characteristics?
- Precision
- Linearity
- Accuracy (Correct answer)
- Sensitivity
Correct answer: Accuracy
Accuracy, sometimes called trueness, is the measure of how closely a test result agrees with an accepted reference value or a 'gold standard' method. [23, 24] By comparing the new analyzer's results to those from the reference method, the laboratory is evaluating the accuracy of the new system. Precision refers to the reproducibility of results when the same sample is tested multiple times. [15, 22]
Question 3: According to Canadian Workplace Hazardous Materials Information System (WHMIS) 2015 guidelines, which hazard is represented by the pictogram showing an exclamation mark?
- Corrosive damage to metals, skin, and eyes
- May cause or is suspected of causing serious long-term health effects (e.g., carcinogen)
- Oxidizing hazard
- May cause less serious health effects, such as skin/eye irritation or act as a skin sensitizer (Correct answer)
Correct answer: May cause less serious health effects, such as skin/eye irritation or act as a skin sensitizer
The exclamation mark pictogram under WHMIS/GHS is used for hazards that are less severe than those indicated by the skull and crossbones or health hazard pictograms. It signifies hazards such as being an irritant (skin and eye), a skin sensitizer, causing acute toxicity (harmful), or having narcotic effects. [5, 17] The corrosion pictogram shows damage to materials and skin, the health hazard (exploding person) pictogram indicates serious long-term effects like carcinogenicity, and the flame over circle represents oxidizing hazards. [1]
Question 4: A Levey-Jennings chart for a daily glucose control shows that the last seven consecutive data points are all above the mean, but still within the ±2 SD limits. According to Westgard multirule procedures, what does this pattern indicate?
- A 2_2s rule violation
- A random error
- A systematic error, specifically a trend (Correct answer)
- An acceptable run as no points are outside ±2 SD
Correct answer: A systematic error, specifically a trend
This pattern describes a trend, which is a type of systematic error where results consistently move in one direction over a period of time. [6] A common Westgard rule (e.g., 7_T) identifies this pattern. It signals a gradual change in the testing system, such as reagent degradation or instrument calibration drift. A 2_2s rule is when two consecutive points exceed the same +2SD or -2SD limit. Random error would show no discernible pattern. Because a specific rule is violated, the run is not automatically acceptable and requires investigation. [8, 18]
Question 5: A batch of used, non-sharp, blood collection tubes containing clotted human blood must be discarded. According to Canadian Standards Association (CSA) guidelines and general biosafety principles, what is the correct disposal method?
- In a regular office garbage bin.
- In a yellow, puncture-resistant biohazard sharps container.
- In a designated, leak-proof biohazard bag/container for autoclaving or incineration. (Correct answer)
- Pouring the contents down the sink and discarding tubes in the regular garbage.
Correct answer: In a designated, leak-proof biohazard bag/container for autoclaving or incineration.
Human blood and body fluids are considered biohazardous waste. Non-sharp items contaminated with this waste, such as blood tubes, must be placed in designated, labeled, and leak-proof biohazard bags or containers for subsequent decontamination, typically by autoclaving or incineration. [28, 29] Regular garbage is incorrect due to the infectious risk. Sharps containers are specifically for items that can puncture skin, like needles. Disposing of blood down a sink is generally not permitted and is an unsafe practice.
Question 6: A satellite clinic sends a lithium heparin tube for potassium analysis to the central hospital lab. The sample is delayed in transit for 8 hours and is not refrigerated. The resulting potassium level is 6.8 mmol/L (critically high), but the patient is asymptomatic. What is the most likely cause of this result?
- Contamination from a lavender (EDTA) top tube.
- A true critical result requiring immediate physician notification.
- Pseudohyperkalemia due to delayed centrifugation. (Correct answer)
- Hemolysis from an excessively small gauge needle used for collection.
Correct answer: Pseudohyperkalemia due to delayed centrifugation.
When whole blood is stored for an extended period at room temperature without being centrifuged, potassium leaks from the red blood cells into the plasma. [3, 9] This process, known as pseudohyperkalemia, falsely elevates the measured potassium level. The lack of patient symptoms strongly suggests a pre-analytical error rather than true hyperkalemia. While EDTA contamination and hemolysis also cause high potassium, the key factor in this scenario is the significant delay in processing. [7, 11]
CSMLS Laboratory Safety and QA Questions and Answers
A medical laboratory technologist spills approximately 10 mL of 1 Molar hydrochloric acid on a countertop.
Which of the following is the most appropriate initial action?