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Quality and safety in the pathology laboratory

Most laboratory errors happen before the test — misidentification, unsuitable specimen, delay and poor fixation — so a good quality system controls the whole chain: from identification in the operating theatre, through internal and external quality control, to rapid reporting of critical values and results; and at the same time it protects staff from chemicals and infection.

לקריאה בעברית

Why it matters in the exam

The bank asks about process stages, fixation and safety. Pre-analytical stage: identification by at least two identifiers (name and ID number or patient number), the right tube, transport time and conditions; for tissue — fixation in 10% neutral buffered formalin, at a volume at least 10 times the tissue volume. In breast cancer the cold ischaemia time (from excision to formalin) should be at most 1 hour, and fixation time between 6 and 72 hours, so that ER, PR and HER2 are reliable.

Analytical stage: internal quality control with control materials and statistical rules (Westgard) that detect drift, and external quality assessment (proficiency testing) that compares with other laboratories; in pathology also double reading of difficult cases and controls for every stain. Post-analytical stage: rapid reporting of a critical or unexpected finding (for example malignancy in a specimen sent as benign, or unexpected infection) directly to the treating doctor, with documentation. Accreditation to ISO 15189 defines the requirements for quality and competence.

Safety: formaldehyde is carcinogenic and irritant, so work is done in a fume hood with suitable ventilation and exposure is monitored; xylene and other solvents are flammable and toxic. Every specimen is treated as infectious (universal precautions), and handling is set by risk assessment; when tuberculosis is suspected, aerosol generation is avoided, for example in frozen section, and when prion disease is suspected there is a special decontamination procedure. Sharps go into dedicated containers. Misidentification is the most dangerous error, because it leads to wrong treatment of two patients.

Key points

• Most errors occur before the test; identification by two identifiers.
• 10% formalin at 10 times the volume; in breast cold ischaemia up to 1 hour and fixation 6–72 hours.
• Internal control (Westgard) and external control (proficiency testing).
• Critical finding — direct, documented reporting.
• Safety: fume hood, universal precautions and prion procedure.

Summary table

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Sources

• ISO 15189: Medical laboratories — Requirements for quality and competence, 2022 — Pre-examination, examination and post-examination processes
• ASCO/CAP Guidelines for breast biomarker testing, 2020–2023 — Cold ischaemia and fixation requirements
• WHO Laboratory Biosafety Manual, 4th edition (2020) — Risk assessment and core requirements

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.