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Knowledge

Pre-analytical, Analytical and Post-analytical Phases

Explore the three major phases of laboratory testing and common activities in each phase.

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:

- Define the three testing phases.
- Identify common examples of errors in each phase.
- Explain why quality management must cover the complete testing pathway.

Pre-analytical, Analytical and Post-analytical Phases

Why the three-phase model matters

Laboratory quality is often discussed using three broad phases. The model helps laboratories identify where a process can fail and where controls are needed.

Pre-analytical phase

This phase includes everything that occurs before the analytical examination.

Typical activities

  • Test request
  • Patient preparation
  • Identification
  • Specimen collection
  • Labeling
  • Transport
  • Receipt
  • Acceptance
  • Processing

Examples of problems

  • Incorrect identification
  • Wrong tube or container
  • Insufficient specimen
  • Clotting
  • Hemolysis
  • Contamination
  • Delay
  • Incorrect storage

The exact significance of a problem depends on the examination.

Analytical phase

This is the measurement or examination itself.

Important controls

  • Appropriate examination procedure
  • Personnel competence
  • Equipment performance
  • Reagent quality
  • Calibration or verification where applicable
  • Internal QC
  • Environmental conditions
  • Documentation

Analytical quality should be evaluated against criteria established for the method and intended use.

Post-analytical phase

This phase begins after examination.

Activities may include:

  • Result review
  • Validation or authorization
  • Reporting
  • Critical-result communication
  • Record management
  • Result correction according to controlled procedures

Connecting the phases

The phases should not be treated as independent silos.

For example, an unsuitable specimen may produce an analytically correct measurement of the wrong material. Conversely, a technically sound result can still create risk if it is attributed to the wrong patient or not communicated appropriately.

Quality indicators

Laboratories can monitor indicators related to the phases, such as specimen rejection, turnaround time, QC performance, reporting errors, or critical-result communication, using definitions appropriate to their quality system.

Key points

  • The three phases describe a connected laboratory process.
  • Each phase has distinct risks and controls.
  • Quality improvement should consider the entire pathway.
  • Laboratory-specific procedures and indicators should define operational requirements.

References

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

Practical learning note

When reviewing a laboratory process, ask three questions:

  1. Before measurement: Was the correct patient and specimen obtained and handled appropriately?
  2. During measurement: Did the examination procedure perform within its defined quality requirements?
  3. After measurement: Was the result correctly reviewed, reported, and communicated?

This simple framework helps learners locate potential sources of error without assuming that every unexpected result is caused by the analytical instrument.

References

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