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Knowledge

The Laboratory Testing Process

An overview of how a laboratory test moves from patient preparation and specimen collection through analysis and reporting.

5 min read Laboratory Quality Assurance #specimen #time
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Learning Objectives

By the end of this resource you should be able to:

- Identify the three broad phases of laboratory testing.
- Give examples of pre-analytical activities.
- Describe key analytical quality elements.
- Describe major post-analytical activities.
- Explain how errors in one phase can affect the final result.

The Laboratory Testing Process

Overview

A laboratory result is produced through a sequence of connected activities. The analytical instrument is only one part of that process.

The testing pathway is commonly divided into:

  1. Pre-analytical phase
  2. Analytical phase
  3. Post-analytical phase

Pre-analytical phase

The pre-analytical phase begins before measurement.

Activities may include:

  • Test selection and request
  • Patient preparation
  • Patient identification
  • Specimen collection
  • Labeling
  • Transport
  • Receipt
  • Acceptance or rejection
  • Processing

Common pre-analytical risks

Examples include:

  • Wrong patient identification
  • Wrong specimen type
  • Incorrect container
  • Insufficient volume
  • Clotted specimen where anticoagulated blood is required
  • Hemolysis
  • Contamination
  • Delayed transport
  • Inappropriate storage

Not every problem requires specimen rejection; the decision should follow the laboratory's validated acceptance criteria.

Analytical phase

The analytical phase is the examination or measurement.

Important elements include:

  • Validated or otherwise appropriately established procedures
  • Trained and competent personnel
  • Equipment suitability
  • Reagent and consumable management
  • Calibration or calibration verification where applicable
  • Internal quality control
  • Environmental monitoring where relevant
  • Documentation

Post-analytical phase

After measurement, the laboratory may need to:

  • Review results
  • Resolve instrument flags or other exceptions
  • Authorize results according to laboratory policy
  • Report results
  • Communicate critical results according to defined procedures
  • Maintain records

Why errors can propagate

A problem introduced during specimen collection can persist through the analytical process. Likewise, a correct analytical measurement can become clinically unsafe if the wrong patient is associated with the result or if a critical result is not communicated according to policy.

Quality management across the pathway

Quality management should therefore address the entire testing process.

Useful controls include:

  • Standardized procedures
  • Competency assessment
  • Quality indicators
  • Internal quality control
  • Equipment maintenance
  • Document and record control
  • Incident investigation
  • Corrective and preventive action
  • Continual improvement

Key points

  • Laboratory testing is a process, not merely an instrument reading.
  • Pre-analytical, analytical, and post-analytical phases are interconnected.
  • Patient identification is a fundamental safety step.
  • Quality management should cover the complete pathway.

References

  • World Health Organization. Laboratory Quality Management System: Handbook.
  • ISO 15189:2022. Medical laboratories — Requirements for quality and competence.