What is the first course of action when the moving average for the previous 20 samples exceeds acceptable limits?

First Course of Action When Moving Average Exceeds Acceptable Limits

When the moving average for the previous 20 samples exceeds acceptable limits, the first course of action should be to run new control materials (option D).

Understanding Moving Average Quality Control

Moving average quality control (MA QC) is a patient-based real-time quality control system that provides continuous monitoring of analytical performance. When a moving average exceeds acceptable limits, it indicates a potential systematic error in the testing process that requires immediate investigation.

Why Run New Control Materials First?

Running new control materials is the most appropriate first action because:

1. It provides immediate verification of the current analytical system performance
2. It helps determine if the issue is persistent or transient
3. It establishes whether the problem is with the instrument or with the previous samples
4. It's a quick diagnostic step before more extensive troubleshooting

Systematic Approach to Moving Average Exceedance

Step 1: Run New Control Materials (First Action)

• Use fresh, properly stored control materials
• Run controls at multiple levels (low, normal, high) if applicable
• Compare results to established acceptable ranges

Step 2: Evaluate Control Results

• If controls are within range: This suggests the issue may be related to the patient samples rather than instrument performance
• If controls are outside range: This confirms an analytical problem requiring further investigation

Step 3: Further Investigation (Only After Step 1)

• Recalibrate the instrument if controls remain out of range 1
• Check for presence of clots in previous samples
• Determine if samples were from a single ward/clinic
• Review maintenance records and reagent lot changes

Evidence-Based Rationale

The approach aligns with laboratory quality control guidelines that emphasize verification of current system performance before more extensive troubleshooting. Moving average quality control is particularly valuable for detecting small shifts in analytical performance that might not be immediately apparent 2, 3.

When MA QC alarms occur, running new control materials provides immediate verification of current system performance and helps distinguish between transient and persistent issues 4. This approach is more efficient than investigating sample sources or checking for clots before confirming whether the analytical system itself is performing properly.

Common Pitfalls to Avoid

• Don't immediately recalibrate: Recalibration without first verifying the issue with control materials can mask underlying problems and potentially introduce new ones
• Don't assume sample issues first: Checking for clots or sample sources before verifying system performance can waste time if the problem is with the analytical system
• Don't ignore moving average alerts: They can detect small systematic errors before conventional quality control methods 5

By following this systematic approach starting with running new control materials, laboratories can efficiently troubleshoot moving average exceedances and maintain analytical quality.