Laboratory Operations, Quality, and Safety
QC versus QA
Quality control (QC) is day-to-day, in-run verification that a test performed as expected - controls, stain checks, temperature logs, new-lot comparison. Quality assurance (QA) is the broader program that prevents problems: procedure manuals, competency assessment, proficiency testing, corrective action, and audit. Expect questions that ask you to classify an activity as one or the other.
Regulatory framework
US clinical laboratories operate under CLIA, with CAP accreditation adding detailed requirements for anatomic pathology. Every test needs a written procedure, documented validation before use, and ongoing monitoring. Reagents are labeled with receipt and opening dates, checked against expiration, and new lots compared with old. Blocks and slides are retained for defined periods and stored so they remain interpretable.
Safety
OSHA's Bloodborne Pathogens Standard requires an exposure control plan, engineering controls, PPE, and hepatitis B vaccination offered to at-risk staff; standard precautions mean treating all fresh tissue as infectious. The Hazard Communication Standard requires a chemical inventory, safety data sheets, and GHS-labeled containers. Formalin is a carcinogen with an OSHA permissible exposure limit of 0.75 ppm as an 8-hour TWA and a 2 ppm short-term exposure limit; it belongs in a ventilated area with a spill kit, and waste is neutralized or handled as hazardous waste. Xylene is flammable and neurotoxic and is stored in a flammable cabinet; glove selection is chemical-specific - thin nitrile is adequate for brief formalin contact but poor against xylene.
Rule of thumb: hazard first, then specimen - no specimen justifies an unlabeled container or an open formalin tray outside a hood.