Laboratory Operations Study Guide

Learning objectives

Distinguish quality control, quality assurance, and quality improvement.
Apply maintenance, calibration, verification, and documentation principles.
Use engineering controls, PPE, and hazard communication appropriately.
Plan validation or verification for method and equipment changes.
Write a complete investigation, corrective action, and effectiveness check.

1. Quality system essentials

Concept	Purpose	Example
Quality control	Detect whether a process or test performed acceptably at the time of use.	Reviewing an H&E control slide before releasing a run.
Quality assurance	Ensure the full system consistently produces acceptable results.	Competency, document control, reagent tracking, audits, and maintenance.
Quality improvement	Use data to reduce errors and improve performance.	Trending recuts, floaters, delayed turnaround, or failed controls.
Document control	Ensure staff use the approved current procedure.	Version, approval, effective date, review cycle, and removal of obsolete copies.
Traceability	Connect specimen, block, slide, reagent, instrument, operator, and result.	Case identifiers and run records that permit investigation.

Quality is a chain: accessioning, fixation, processing, embedding, cutting, staining, scanning, interpretation, and reporting can each create or reveal error.

2. Equipment and environmental control

Preventive maintenance: scheduled actions intended to prevent failure.
Calibration: establishes the relationship between an instrument indication and a traceable reference.
Verification: confirms that performance meets defined requirements in the local setting.
Function check: routine evidence that a device is operating as expected before or during use.

Equipment	High-yield controls
Tissue processor	Temperature, vacuum/pressure, reagent position, alarms, retort cleanliness, cleaning cycle, maintenance.
Embedding center	Paraffin temperature, cold plate, forceps wells, cleanliness, cassette identity workflow.
Microtome	Blade holder, specimen clamp, thickness setting, lubrication/maintenance, handwheel lock.
Water bath and oven	Verified temperatures, cleanliness, water quality, contamination control.
Stainer/coverslipper	Station identity, timing, reagent levels, carryover, water flow, glass quality, alarms.
Cryostat	Temperature, blade safety, decontamination, infection control, defrost and maintenance.
Scanner/image system	Focus, color, resolution, file identity, storage, network, monitor, and validation for intended use.

3. Safety hierarchy

Elimination/substitution: remove or replace a hazard when feasible.
Engineering controls: fume hoods, local exhaust, closed processors, splash shields, sharps design.
Administrative controls: SOPs, training, signage, exposure monitoring, restricted access, schedules.
PPE: gloves, coat/gown, eye/face protection, and respiratory protection when required by a formal program.

Common histology hazards

Formaldehyde, xylene and substitutes, alcohols, acids, bases, oxidizers, silver solutions, dyes, picric acid, mercury compounds, and carcinogenic/mutagenic reagents.
Microtome and cryostat blades, broken glass, hot paraffin, ovens, electrical equipment, compressed gas, and repetitive motion.
Fresh or unfixed human tissue, aerosols, bloodborne pathogens, and contaminated cryostats.

PPE is not the first control. Use the hierarchy of controls and current SDS information; do not rely on gloves alone.

4. Validation and change control

Validation demonstrates that a method is fit for its intended use. Verification confirms that an established method performs acceptably in the local laboratory. The exact regulatory meaning varies by setting, so follow the applicable quality system.

Before a change

Define the intended use and acceptance criteria.
Identify risks, affected specimen types, stains, antibodies, probes, instruments, and users.
Select representative positive, negative, weak-positive, and challenging materials.
Compare old and new conditions when possible.
Document results, deviations, approval, training, and implementation date.

Examples requiring controlled evaluation

New fixative, processor schedule, paraffin, decalcifier, blade type, charged slide, stainer, retrieval solution, detection chemistry, scanner, or software algorithm.
Major lot change or supplier change when performance may differ.
Moving a method to a new platform or changing preanalytic windows.

5. Investigation and corrective action

Contain: stop release when necessary and identify potentially affected material.
Define: state what happened, when, where, how often, and what should have happened.
Gather evidence: controls, logs, lots, instruments, operators, temperatures, maintenance, recent changes.
Find root cause: distinguish a true cause from a symptom or convenient assumption.
Correct: address the immediate event.
Prevent: change the system to reduce recurrence.
Check effectiveness: confirm with data that the action worked and did not create another problem.

Good documentation is specific: “retrained staff” alone is weak unless the skill gap, training content, competency evidence, and effectiveness measure are defined.

Practice quiz

Best: —

1. Reviewing an H&E control slide is primarily: Marketing Quality control Specimen grossing Billing

2. Preferred control before PPE when feasible: Ignore the hazard Work faster Use thinner gloves only Engineering control

3. Establishing instrument agreement with a traceable standard is: Calibration Coverslipping Grossing Differentiation

4. Document control ensures: Every employee writes a different SOP Old procedures remain at benches The approved current procedure is used Changes need no approval

5. First action after discovering a potentially serious failed run: Release all slides Contain affected material Delete records Blame an operator

6. Before introducing a new stainer, the laboratory should: Use it immediately without controls Assume vendor data is sufficient for every use Skip training Validate or verify performance as required

7. Scheduled service intended to prevent breakdown is: Preventive maintenance Root-cause analysis Differentiation Accessioning

8. A CAPA is incomplete without: A longer title More signatures only An effectiveness check Deleting the deviation

9. The main purpose of traceability is to: Reduce slide labels Reconstruct what happened to a specimen Avoid maintenance Replace controls

10. The strongest root-cause conclusion is: “Human error” with no evidence The first guess The most senior person's opinion An evidence-supported system cause

References and scope

ASCP Board of Certification. Current HT and HTL examination content guidelines and suggested reading list.
Carson FL, Cappellano CH. Histotechnology: A Self-Instructional Text. 5th ed. ASCP Press; 2020.
Applicable institutional policies, CLIA/CAP/ISO requirements, OSHA standards, manufacturer manuals, and SDS documents.

Regulatory requirements vary by laboratory and jurisdiction. Independent educational content; not affiliated with or endorsed by ASCP.