Introduction
Laboratory work requires accuracy, consistency and attention to detail.
However, errors can occur at different stages of laboratory operations.
An error may occur before testing begins, during the analytical process or after a result has been produced.
Understanding where errors occur is important because effective prevention is not simply about telling individuals to “be more careful.”
Laboratories can reduce errors by improving:
- Procedures
- Training
- Equipment management
- Documentation
- Quality control
- Communication
- Workflow design
- Risk management
- Continuous improvement
A useful laboratory quality system therefore looks beyond the immediate mistake and considers the conditions that allowed the error to occur.
1. What Is a Laboratory Error?
A laboratory error is a mistake, deviation or failure in a laboratory process that can affect the quality, reliability, traceability or timely communication of laboratory work.
Errors can occur during:
- Pre-analytical processes
- Analytical processes
- Post-analytical processes
The exact classification can vary depending on the laboratory and testing environment.
Not every error necessarily produces an incorrect final result, but an error may still indicate a weakness that deserves investigation.
2. Why Is Error Prevention Important?
Laboratory errors can affect:
- Sample integrity
- Measurement quality
- Test results
- Equipment reliability
- Documentation
- Reporting
- Turnaround time
- Safety
- Laboratory efficiency
The significance of an error depends on the activity and the consequences associated with it.
A laboratory should therefore have processes for identifying, evaluating and managing errors according to their potential impact.
3. Pre-Analytical Errors
Pre-analytical activities occur before the actual testing or measurement.
Common examples include:
Incorrect sample identification
A sample may be incorrectly labelled, inadequately identified or associated with the wrong request.
Appropriate identification procedures are therefore essential.
Wrong sample container
A procedure may require a specific container, tube or preservative.
Using an inappropriate container can affect sample suitability.
Insufficient sample
There may not be enough sample material to perform the required procedure.
Poor sample storage
Some samples require specific temperature, environmental or time conditions.
Failure to maintain those conditions can affect sample integrity.
Delayed transportation
Delays between collection and testing may affect certain types of samples.
Contamination
Improper collection, handling or storage can introduce unwanted material into a sample.
Incorrect preparation
Examples may include incorrect mixing, dilution or preparation of materials before analysis.
4. Analytical Errors
Analytical errors occur during testing, measurement or analysis.
Examples include:
- Incorrect test procedure
- Incorrect instrument settings
- Pipetting errors
- Incorrect reagent preparation
- Expired or unsuitable reagents
- Equipment malfunction
- Inadequate equipment maintenance
- Calibration or verification problems
- Poor temperature control
- Cross-contamination
- Failure to follow an approved method
- Incorrect calculation
- Incorrect data entry
These errors can affect the reliability or validity of laboratory results.
5. Post-Analytical Errors
Post-analytical errors occur after testing has been completed.
Examples include:
- Incorrect transcription
- Incorrect data entry
- Reporting the wrong result
- Failure to review results appropriately
- Delayed reporting
- Failure to communicate important information
- Incorrect record storage
- Loss of documentation
A technically appropriate measurement can still create a problem if the result is incorrectly recorded, interpreted, communicated or reported.
6. Equipment-Related Errors
Laboratory equipment is another important source of potential problems.
Incorrect equipment use
Personnel may operate equipment without adequate training or without following the relevant SOP.
Poor maintenance
Equipment that is not appropriately maintained may become unreliable.
Calibration or verification problems
Where calibration or verification is required, inappropriate status or performance can affect confidence in measurements.
Environmental conditions
Some instruments may be sensitive to:
- Temperature
- Humidity
- Electrical supply
- Vibration
- Dust
- Location
Ignoring warning signs
Unusual sounds, error codes, unstable readings or unexpected performance should not automatically be ignored.
The laboratory should follow an appropriate troubleshooting and escalation process.
7. Reagent and Material-Related Errors
Laboratory processes may also be affected by problems involving reagents, consumables and other materials.
Potential problems include:
- Expired reagents
- Incorrect reagent
- Incorrect preparation
- Incorrect storage
- Contamination
- Inadequate labelling
- Poor stock management
- Use of unsuitable materials
Appropriate inventory, storage, identification and quality-control procedures can help reduce these risks.
8. Environmental Errors and Conditions
The laboratory environment can influence some processes and equipment.
Depending on the activity, relevant conditions may include:
- Temperature
- Humidity
- Lighting
- Vibration
- Dust
- Electrical supply
- Ventilation
- Cleanliness
The laboratory should identify environmental conditions that are important to its activities and establish appropriate controls where necessary.
9. Human-Factor Errors
Laboratory errors can involve human factors such as:
- Fatigue
- Distractions
- Inadequate training
- Communication problems
- Unclear instructions
- Excessive workload
- Poorly designed workflows
- Failure to verify information
However, it is important not to assume that an individual is always the sole cause of an error.
A recurring error may indicate a system or process weakness.
For example, an operator may repeatedly enter the wrong equipment identification because two similar instruments have confusing labels or because the form design encourages mistakes.
10. Documentation Errors
Documentation is an important part of laboratory operations.
Common documentation problems include:
- Missing entries
- Incorrect dates
- Unclear handwriting
- Incorrect equipment identification
- Missing signatures or identification where required
- Incomplete maintenance records
- Incorrect transcription
- Failure to document deviations
- Use of obsolete procedures
Good documentation should make it possible to understand what happened, when it happened and who performed or authorized the relevant activity, according to the laboratory’s procedures.
11. Communication-Related Errors
Communication problems can contribute to laboratory errors.
Examples include:
- Unclear instructions
- Incomplete handover information
- Failure to communicate equipment faults
- Failure to communicate changes to procedures
- Misunderstanding of responsibilities
- Incomplete information accompanying samples or requests
Clear communication channels and appropriate documentation can help reduce these risks.
12. How Can Laboratory Errors Be Prevented?
Error prevention should use multiple controls rather than relying on individual attention alone.
1. Use clear SOPs
Well-written procedures reduce ambiguity.
2. Train laboratory personnel
Training should address both theoretical knowledge and practical performance.
3. Assess competency
Where appropriate, personnel should demonstrate that they can perform assigned tasks correctly.
4. Use checklists
Checklists can be particularly useful for repetitive or critical procedures.
5. Maintain equipment
Preventive maintenance can help reduce equipment-related failures.
6. Manage calibration and verification
Equipment used for measurements should have an appropriate calibration or verification process where required.
7. Apply quality control
QC processes can help identify problems before work or results are released, where applicable.
8. Control documents
Personnel should have access to current approved procedures.
9. Improve communication
Clear communication between laboratory personnel and relevant stakeholders can reduce misunderstandings.
10. Record incidents and near misses
Learning from problems and appropriate near-miss information can help identify weaknesses before they result in more serious consequences.
13. The Role of Checklists
Checklists can provide a simple way to ensure that important steps are not overlooked.
A checklist may be useful for:
- Equipment startup
- Sample receipt
- Equipment shutdown
- Maintenance
- Calibration preparation
- Safety checks
- Quality-control procedures
A checklist should support, rather than replace, appropriate training and professional judgment.
14. Understanding Root Causes
When an error occurs, simply identifying the person involved may not explain why it happened.
For example:
A laboratory professional records the wrong equipment identification number.
A superficial explanation might be:
“The person was careless.”
A broader investigation might reveal:
- Equipment labels are difficult to read.
- Two similar instruments are positioned beside each other.
- The form design is confusing.
- There is no verification step.
- The workload is unusually high.
The appropriate response may therefore involve improving the system rather than simply reminding the individual to be more careful.
15. Error Prevention and Corrective Action
When a significant error or nonconformity is identified, the laboratory may need to distinguish between immediate correction and corrective action.
Immediate correction
Addresses the immediate problem.
Corrective action
Addresses the cause of the nonconformity to help prevent recurrence.
For example, if an incorrect equipment number is entered:
Correction: Correct the affected record according to the laboratory’s documentation procedure.
Corrective action: Investigate why the wrong identification was entered and improve the identification or verification process if necessary.
The exact response should depend on the significance and risk associated with the event.
16. Learning From Near Misses
Not every process failure produces an actual error or incorrect result.
A near miss may occur when an error is identified before it causes harm or affects the final outcome.
For example, a sample may be found to have an identification discrepancy before testing begins.
Recording and reviewing appropriate near misses can help laboratories identify weaknesses before they produce more significant problems.
The laboratory should follow its established procedures for reporting and reviewing such events.
17. Practical Error-Prevention Checklist
Before starting a laboratory task, ask:
- Am I using the correct procedure?
- Is the equipment suitable and ready?
- Is the equipment status acceptable?
- Are the materials and reagents appropriate?
- Is the sample correctly identified?
- Are the required environmental conditions satisfied?
- Have I confirmed critical settings?
- Do I know what records must be completed?
- Do I understand the critical steps?
- What should I do if the process does not behave as expected?
These questions encourage a more controlled workflow.
18. Practical Example: Preventing a Sample-Handling Error
Imagine a laboratory receives several samples at the same time.
Potential risks include:
- Similar sample identifiers
- Incorrect labelling
- Wrong storage location
- Delayed processing
- Incorrect documentation
Possible controls include:
- Confirm identification.
- Verify accompanying documentation.
- Use the correct container and storage conditions.
- Record receipt appropriately.
- Follow the applicable sample-handling SOP.
- Escalate discrepancies before proceeding.
The exact controls depend on the laboratory and type of sample.
19. Practical Example: Preventing an Equipment-Related Error
Suppose an analytical instrument begins producing unexpected readings.
A useful prevention and response process may include:
- Confirm that the correct procedure is being followed.
- Check the equipment status.
- Review relevant QC information.
- Check whether maintenance is current.
- Confirm calibration or verification status where applicable.
- Check relevant environmental conditions.
- Review error messages or abnormal indications.
- Stop use if the equipment may be unsuitable or unsafe.
- Report and document the problem.
- Follow the laboratory’s troubleshooting and escalation procedure.
The laboratory should not assume that an unexpected result is caused by the instrument alone.
Sample, method, reagent, operator and environmental factors may also need to be considered.
20. Error Prevention Is a Team Responsibility
Quality should not depend on one person remembering everything.
A strong laboratory system combines:
People + Procedures + Equipment + Training + Documentation + Quality Control + Risk Management + Continuous Improvement
Each component supports the others.
For example:
- Training helps people understand procedures.
- SOPs provide controlled instructions.
- Equipment management supports reliable operation.
- QC helps monitor processes.
- Documentation provides traceability.
- Incident investigation identifies weaknesses.
- Corrective action addresses appropriate causes.
- Continuous improvement strengthens the system.
21. Building an Error-Prevention Culture
An effective error-prevention culture encourages personnel to report problems and potential risks rather than hiding them.
This does not mean that every error should be treated in the same way.
The laboratory should consider:
- What happened?
- What was the potential or actual impact?
- Why did it happen?
- What controls were already in place?
- Were those controls effective?
- What additional controls are appropriate?
- Does corrective action need to be taken?
- How will effectiveness be monitored?
The objective is to learn from laboratory events and improve the system.
22. Frequently Asked Questions
What are the three main categories of laboratory errors?
A commonly used framework divides errors into pre-analytical, analytical and post-analytical stages.
What is a pre-analytical error?
It is an error occurring during activities before the actual analysis or measurement, such as sample identification, collection, handling or storage.
What is an analytical error?
An analytical error occurs during the testing or measurement process and may involve equipment, methods, reagents, calculations, technique or other factors.
What is a post-analytical error?
A post-analytical error occurs after testing, such as incorrect transcription, reporting, interpretation, communication or record handling.
What causes laboratory errors?
Causes can include inadequate procedures, equipment problems, training gaps, communication problems, environmental conditions, workload and other process or system factors.
How can laboratory errors be reduced?
Useful controls include clear SOPs, staff training, competency assessment, equipment maintenance, calibration or verification where applicable, quality control, document control, good communication and systematic investigation of incidents.
Should laboratory errors always be blamed on the person who made the mistake?
Not necessarily. Investigating the process and underlying causes can reveal system weaknesses that contributed to the error.
What is the difference between an error and a near miss?
An error involves a failure or deviation that may affect laboratory work. A near miss is an event that could have resulted in an unwanted outcome but was identified or prevented before that outcome occurred. Definitions may vary between quality systems.
Why is root-cause investigation important?
It can help the laboratory understand why an error occurred and determine whether changes to procedures, equipment, training or other controls are needed to reduce recurrence.
Conclusion
Laboratory errors can occur at many points, from sample collection through testing and final reporting.
The goal of a good laboratory quality system is not merely to identify who made an error.
It is to understand what happened, why it happened and how the process can be improved to reduce the likelihood of recurrence.
Effective error prevention combines:
- Competent personnel
- Appropriate equipment
- Clear procedures
- Quality control
- Good documentation
- Risk management
- Effective communication
- Continuous improvement
A laboratory becomes more resilient when error prevention is designed into its processes rather than left entirely to individual memory and caution.
Knowledge Tech Hub Practical Takeaway
When an error occurs, ask:
What happened?
Why did it happen?
What allowed it to happen?
What was the potential or actual impact?
What can be changed to reduce the chance of recurrence?
These questions encourage a process-improvement mindset rather than a purely blame-focused approach.
Suggested Internal Links
- Laboratory Safety: Essential Rules Every Laboratory Professional Should Know
- Common Laboratory Hazards and How to Prevent Them
- Laboratory Equipment: Names, Functions and Uses
- How to Use Laboratory Equipment Correctly: A Beginner’s Guide
- Laboratory Equipment Maintenance: A Complete Practical Guide
- Preventive Maintenance for Laboratory Equipment
- Laboratory Equipment Troubleshooting: A Practical Guide
- Laboratory Equipment Calibration: What Every Laboratory Professional Should Know
- Laboratory Quality Control: A Practical Guide for Beginners
- Laboratory Quality Assurance: Principles, Processes and Best Practices
- Laboratory Documentation and Record Keeping
- Laboratory Standard Operating Procedures (SOPs): A Practical Guide
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References and Further Reading
- World Health Organization (WHO), Laboratory Quality Management System: Handbook
- ISO 15189 — Medical laboratories — Requirements for quality and competence, where applicable
- ISO/IEC 17025 — General requirements for the competence of testing and calibration laboratories, where applicable
- ISO 9001 — Quality management systems — Requirements
- Applicable laboratory quality-management procedures
- Applicable national laboratory regulations and accreditation requirements
- Laboratory equipment manufacturer manuals and technical documentation
Note: Laboratories should use the current editions of applicable standards, regulations and accreditation requirements when developing error-management and prevention procedures.
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