12.3 Quality Assurance, CLIA/CAP Compliance & Records Retention
Key Takeaways
- Quality control monitors the immediate analytical run through control slides and equipment checks, while quality assurance monitors the whole pre-analytic, analytic, and post-analytic workflow.
- CLIA classifies histopathology, gross examination, microtomy, and special staining as high-complexity testing, which requires documented personnel qualifications and competency assessment.
- CLIA competency assessment has six required elements and is performed semiannually during the first year of a new employee's duties and annually thereafter.
- CLIA minimum record retention is 10 years for histopathology slides and pathology reports, 5 years for cytology slide preparations, and 2 years for paraffin blocks; CAP requires blocks for 10 years.
- Every special stain and immunohistochemistry run requires an appropriate positive control, and a failed control invalidates the patient result until the run is repeated.
12.3 Quality Assurance, CLIA/CAP Compliance & Records Retention
ASCP HT Core Principle: Quality control (QC) answers "did this run work?" - the control slide, the bath temperature, the reagent lot. Quality assurance (QA) answers "is this laboratory working?" - accessioning accuracy, turnaround time, recut rate, correlation of frozen and permanent diagnoses, and corrective action follow-through. Under Laboratory Operations, ASCP tests quality control as a sub-topic of every content area, not just this one.
Regulatory Framework: CLIA, CAP, and The Joint Commission
- CLIA '88 complexity. Histopathology, gross examination, microtomy, and special stains and immunohistochemistry are high-complexity testing. High complexity brings specific requirements for personnel qualifications, a qualified technical supervisor and general supervisor, documented procedures, and competency assessment.
- CAP accreditation. The College of American Pathologists inspects accredited laboratories on a two-year cycle with a documented self-inspection in the intervening year, using discipline-specific checklists. CAP requirements are frequently more stringent than the CLIA floor.
- Proficiency testing. Laboratories enroll in surveys appropriate to their menu; special stain and immunohistochemistry surveys are graded and require documented review and corrective action when a challenge is missed.
- The Joint Commission and CAP both require at least two unique patient identifiers on every container, cassette, slide, and report - typically name plus accession number or medical record number - applied with solvent-resistant labeling.
CLIA competency assessment: the six elements
Competency is assessed semiannually during the first year an employee performs a given duty, and annually thereafter, using all six of the following:
- Direct observation of routine test performance, including specimen handling and processing.
- Monitoring of the recording and reporting of results.
- Review of intermediate results, worksheets, quality control records, proficiency testing results, and preventive maintenance records.
- Direct observation of instrument maintenance and function checks.
- Assessment of test performance using previously analyzed specimens, internal blind samples, or external proficiency testing material.
- Assessment of problem-solving skills.
Record and Material Retention
| Material | CLIA minimum retention | Note |
|---|---|---|
| Histopathology slides | 10 years from date of examination | CAP concurs |
| Cytology slide preparations | 5 years from date of examination | CAP concurs |
| Paraffin blocks | 2 years from date of examination | CAP requires 10 years |
| Pathology reports | 10 years | Often longer under state law |
| Requisitions and quality system records | 2 years | |
| Wet tissue (specimen remnants) | Until the diagnosis is made | CAP: at least 2 weeks after the final report |
Exam trap: the retention period for blocks and the retention period for slides are different under CLIA, and CAP's block requirement is five times the CLIA minimum. State law and institutional policy may extend any of these, and the longest applicable requirement governs.
Equipment Monitoring and Preventive Maintenance
Thermal equipment is logged every day of use with a NIST-traceable thermometer.
- Flotation baths: 40 degrees C to 45 degrees C, which is 5 to 10 degrees C below the paraffin melting point. Above roughly 48 degrees C the section over-expands and shows nuclear bubbling and parched-earth cracking; below about 38 degrees C folds will not flatten.
- Embedding consoles and paraffin reservoirs: 56 degrees C to 60 degrees C, which is 2 to 4 degrees C above the melting point. Above 62 degrees C tissue shrinks and antigens degrade.
- Slide drying ovens: 60 degrees C to 65 degrees C for 20 to 30 minutes.
- Refrigerators: 2 degrees C to 8 degrees C. Freezers: -20 degrees C routine, -80 degrees C for molecular material.
- Cryostat chambers: -15 degrees C to -20 degrees C routine, about -10 degrees C for brain, -25 degrees C to -30 degrees C for fatty breast.
- Preventive maintenance: microtomes cleaned daily and lubricated on schedule; processors checked for reagent specific gravity and rotated on a documented schedule; stainers and coverslippers serviced per the manufacturer's interval.
An out-of-range reading is not corrected by writing a new number. It requires a documented corrective action and an assessment of every specimen handled since the last acceptable reading.
Control Slide Management
- Special stains: every run carries a known positive control stained simultaneously with the patient slide - liver or kidney for PAS, appendix or lung for acid-fast, liver for reticulin, a known amyloid block for Congo red. The control is read before the patient slide is released.
- Immunohistochemistry: each run needs an on-slide or same-run positive tissue control and a negative reagent control in which the primary antibody is replaced by diluent. Internal positive controls within the patient tissue are used when available.
- Control failure invalidates the run. The correct response is to repeat the stain and document the failure and its cause, not to interpret a patient slide against a failed control.
- Reagent and lot control: new lots of antibody, dye, and detection reagent are verified against the previous lot before clinical use, and lot numbers with expiration dates are recorded.
Quality Indicators and Corrective Action
Laboratories monitor a defined set of indicators, review them at scheduled quality meetings, and act on trends:
| Indicator | What it detects |
|---|---|
| Recut and re-stain rate | Microtomy and staining quality |
| Turnaround time | Workflow bottlenecks; many laboratories target 90 percent of routine biopsies reported within two working days |
| Labeling and identification discrepancies | Accessioning and grossing accuracy |
| Block and slide localization failures | Tracking system effectiveness |
| Frozen section to permanent section correlation | Intraoperative diagnostic accuracy; discrepancies and deferrals are reviewed |
| Proficiency testing performance | Analytic accuracy against peer laboratories |
Corrective action follows a defined path: identify and contain, investigate root cause, correct, verify that the correction worked, and document the whole sequence. An occurrence report that never closes is itself a deficiency at inspection.
A histotechnician has been performing microtomy and special stains for four months. Under CLIA, how often must competency be assessed during this first year, and which activity satisfies one of the six required elements?
A CAP-accredited laboratory is writing its retention policy. Which combination meets both the CLIA minimum and the CAP requirement?
During a Congo red run for suspected cardiac amyloidosis, the known positive control block shows no apple-green birefringence under polarized light, while the patient section also appears negative. What is the correct action?