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Cytogenetics

Record Quality Indicators

Quality Indicators (QIs) are quantifiable measures used to monitor the performance of laboratory processes. In Cytogenetics, “Quality” is defined not just by the accuracy of the diagnosis, but by the timeliness of the result and the technical excellence of the preparation. Laboratories must select, track, and review these indicators regularly (typically monthly or quarterly) as part of their Quality Assessment (QA) plan

Pre-Analytical Indicators (Specimen Quality)

These indicators track problems that occur before the testing begins. They help the lab identify issues with specific clinics or collection sites

  • Rejection Rate
    • Metric: The percentage of specimens rejected due to labeling errors, wrong container type, or improper transport temperature
    • Goal: < 1%
  • Specimen Age
    • Metric: The average time from Collection to Receipt
    • Importance: Cells (especially in amniotic fluid or blood) begin to die after 24–48 hours. Tracking delays helps improve logistics/courier services

Analytical Indicators (Technical Quality)

These metrics assess the quality of the slide preparation and the microscopic analysis. They ensure the lab is meeting the standards required for accurate diagnosis

  • Band Resolution (Banding Level)
    • Metric: The average “Band Level” (e.g., 400, 550, 650 bands per haploid set) achieved on routine cases
    • Requirement:
      • Constitutional (Blood/Amnio): Generally requires \(\ge\) 550 bands. This resolution allows for the detection of small deletions/duplications
      • Oncology (Bone Marrow): Often lower due to poor chromosome morphology in cancer cells, but labs should strive for \(\ge\) 400 bands
    • Documentation: Each analyzed case is assigned a band level score by the laboratory scientist . The Laboratory Director reviews the monthly average. A drop in average band level triggers an investigation (e.g., Check the Trypsin or Slide Drying chamber)
  • Success Rate (Culture Yield)
    • Metric: The percentage of cases that yield analyzable metaphases
    • Importance: High failure rates in specific tissues (e.g., CVS) indicate a need for technical retraining or media adjustment

Post-Analytical Indicators (Reporting)

These indicators focus on the delivery of the result to the clinician

  • Turnaround Time (TAT)
    • Metric: The number of calendar days from Specimen Receipt: to Final Report Sign-Out
    • Benchmarks (Typical):
      • STAT Newborn (Blood): 3–5 days
      • Routine Prenatal (Amnio): 7–10 days
      • Routine Oncology (Marrow): 5–7 days
      • Peripheral Blood (Constitutional): 14–21 days
    • Outliers: The lab tracks the percentage of cases exceeding the TAT goal (e.g., “90% of Amnios completed within 10 days”). Chronic delays indicate staffing shortages or workflow bottlenecks
  • Corrected Reports (Amendment Rate)
    • Metric: The number of reports that had to be corrected after release due to errors
    • Classification:
      • Clerical Error: Typo in patient name, wrong doctor copied
      • Analytical Error: Wrong karyotype reported (Major Sentinel Event)
    • Goal: Minimize to near zero. A high rate of clerical corrections suggests a need for better LIS proofreading features or “second check” protocols

Error Reporting & Management

When a deviation from standard procedure occurs, it is recorded as an “Occurrence” or “Variance.”

  • Categorization of Errors
    • Near Miss: An error caught before it reached the patient/doctor (e.g., a laboratory scientist labeled a slide wrong, but the checker caught it before analysis). These are valuable learning opportunities
    • Non-Conforming Event: An error that occurred (e.g., a probe failed QC but was used anyway)
  • Root Cause Analysis (RCA)
    • For significant errors (especially those affecting patient care), a formal RCA is conducted to ask “Why?” five times until the core systemic issue is found (e.g., “Tech mislabeled slide” \(\rightarrow\) Why? \(\rightarrow\) “Distracted by phone” \(\rightarrow\) Why? \(\rightarrow\) “Phone is on the workbench” \(\rightarrow\) Solution: Move phone away from critical setup area)

Proficiency Testing (PT) Performance

  • Metric: Performance on external surveys (like CAP)
  • Requirement: 100% accuracy is the goal. Any score < 80% is a failure
  • Action: Any PT failure requires immediate suspension of testing for that analyte, investigation, and retraining

Summary Table of Common Quality Indicators

Indicator Type Example Metric Target Goal Corrective Action Trigger
Pre-Analytical Rejection Rate < 1% > 2% rejected
Analytical Band Level (Blood) > 550 bands Drop to < 500 bands
Analytical Culture Failure (Marrow) < 5% > 10% failure rate
Post-Analytical Turnaround Time (STAT) 90% in < 5 days < 80% meeting TAT
Post-Analytical Amended Reports < 1% Spike in clerical errors