How often should quality control (QC) specimens be run on automated cell counters?

Frequency of Quality Control Specimens on Automated Cell Counters

Quality control specimens should be run on automated cell counters once per shift or after reagents are changed or the instrument is adjusted (option B).

Rationale for QC Frequency Requirements

Quality control in laboratory operations serves several critical functions:

1. Ensuring accuracy and precision of test results
2. Validating test performance of automated systems
3. Monitoring system stability over time

Guidelines on QC Frequency

The most recent and authoritative guidelines recommend running QC specimens at specific intervals:

• QC samples should be included in every analytical run to evaluate assay performance and address potential errors 1
• At a minimum, QC samples should be run at the beginning and end of each analytical run 1
• For studies lasting more than 3 days, some form of QC should be performed on each day of testing 1
• Daily QC is recommended when testing extends beyond a single day 2

Specific Requirements for Cell Counters

For automated cell counters specifically:

• QC should be performed once per shift to ensure consistent performance throughout the day 2
• Additional QC is required whenever reagents are changed or instruments are adjusted 2
• QC should be run to verify that the instrument meets manufacturer specifications for optical alignment and performance 1

Implementation of QC Procedures

Required QC Materials

• Use three QC samples that cover a range of concentrations (low, average, and high) 1
• Use the same lot of QC samples over time to help detect system or operator performance changes 1
• QC samples should be the same specimen type as test samples whenever possible 1

QC Failure Response

• A single day of out-of-range results for a given parameter does not invalidate all results 1
• However, two consecutive days of out-of-range results invalidate the results for those testing periods 1, 2
• When QC failures occur, an investigation should be initiated to determine the root cause before testing resumes 1
• Overall, QC results should be in range 95% of the time 1

Common Pitfalls to Avoid

1. Inadequate QC frequency: "Streamlined QC" (weekly instead of daily) is generally not appropriate for clinical laboratory testing 1, 2

2. Ignoring QC trends: Even when QC results are within range, trends may indicate developing issues 2

3. Overreliance on imperfect QC materials: Supplement with process monitoring when necessary 2

4. Failure to document QC activities: All quality assurance activities should be documented 1

5. Not maintaining consistent QC procedures: The International Council for Standardization in Haematology (ICSH) has noted significant diversity in QC practices among laboratories, highlighting the need for standardized approaches 3, 4

The most recent guidelines from regulatory bodies and professional organizations clearly support option B - running QC specimens once per shift or after reagents are changed or the instrument is adjusted - as the appropriate frequency for quality control on automated cell counters.