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Knowledge

Understanding Laboratory Specimens

Learn why specimen type, collection, identification, transport, and processing are critical to laboratory result quality.

5 min read Phlebotomy / Specimen Collection #specimen #time #temperature #volume
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Learning Objectives

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

- Define a laboratory specimen.
- Identify common specimen types.
- Explain why specimen selection and identification matter.
- Identify common pre-analytical specimen problems.
- Explain why transport and stability requirements are test-specific.

Understanding Laboratory Specimens

Overview

A laboratory specimen is patient-derived material collected for examination or measurement.

The specimen is the starting material for many laboratory investigations. Its identity, type, quality, quantity, and handling can determine whether the requested examination can be performed reliably.

Common specimen types

Depending on laboratory scope, specimens may include:

  • Whole blood
  • Serum
  • Plasma
  • Urine
  • Stool
  • Sputum
  • Swabs
  • Cerebrospinal fluid
  • Other body fluids
  • Tissue
  • Cellular material

Each examination has specific specimen requirements.

Specimen selection

The correct specimen depends on the clinical question and examination method.

Important considerations may include:

  • Anatomical site
  • Specimen type
  • Collection container
  • Additive
  • Required volume
  • Timing
  • Transport conditions
  • Stability

Patient identification

Correct identification is a fundamental patient-safety requirement.

The laboratory's approved identification process should be followed consistently. A specimen that cannot be reliably associated with the correct patient may require rejection or investigation according to laboratory policy.

Specimen integrity

Common specimen problems include:

Hemolysis

Breakdown of red blood cells can alter some measurements and may interfere with selected analytical methods.

Clotting

Clotting can make an anticoagulated specimen unsuitable for examinations that require whole blood without clotting.

Insufficient volume

Some examinations require minimum quantities for reliable testing or repeat analysis.

Contamination

Contamination can alter microbiology, urinalysis, chemistry, or other results depending on the specimen.

Delayed processing

Cells and analytes can change over time. The effect depends on the specimen and examination.

Transport and stability

Transport requirements may involve:

  • Time limits
  • Temperature
  • Protection from light
  • Position or handling
  • Appropriate packaging
  • Prevention of leakage or contamination

Stability is not universal; it must be established for the particular examination and specimen.

Acceptance and rejection

Laboratories should maintain defined criteria for specimen acceptance and rejection.

A rejection decision should be based on patient safety, examination requirements, specimen integrity, and applicable laboratory procedures rather than an informal rule.

Key points

  • A specimen must be appropriate for the requested examination.
  • Correct identification is essential.
  • Container, volume, transport, and storage can affect specimen suitability.
  • Hemolysis, clotting, contamination, and delay can compromise testing.
  • Detailed specimen requirements belong in validated laboratory procedures and dedicated LabGoTo reference resources.

References

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