Validation Study in Medical Laboratory | Step-by-Step Guide

Introduction

Validation is a critical quality assurance process that ensures a laboratory examination procedure consistently provide  accurate, reliable, and clinically meaningful results. Before a new test method, instrument, software, or examination procedure is introduced into routine patient testing, the laboratory must demonstrate that it performs as intended under its own operating conditions.

According to ISO 15189:2022, validation is the confirmation, through the provision of objective evidence, that the requirements for a specific intended use or application have been fulfilled.

What Is a Validation Study?

A validation study is a documented process used to demonstrate that an examination procedure, test method, instrument, software application, or laboratory-developed test consistently performs as intended and is suitable for its intended clinical use.

Step-by-Step Guide to Conducting a Validation Study in a Medical Laboratory

Step 1: Define the Purpose and Scope of the Validation

The first and most important step in any laboratory validation study is to clearly define the purpose and scope of the validation. This stage establishes the foundation for the entire validation process and ensures that the study is performed systematically, in compliance with ISO 15189:2022, regulatory requirements, and laboratory quality management standards.

Purpose:

Demonstrate the reliability, accuracy, and consistency of patient test results. Validating a new reagent, assay kit, or software. Introducing a new analytical method or instrument. Implementing a new test before routine patient reporting. Assessing performance after major equipment upgrades or relocation.

Examples:

The purpose of this validation study is to demonstrate that the Fully Automated Chemistry Analyzer XYZ-500 produces accurate, precise, and reliable test results suitable for routine clinical use in accordance with ISO 15189:2022.

Scope:

Test or analyte to be validated Instrument or analyzer Reagent and calibration system Sample types (serum, plasma, urine, whole blood, etc.) Measuring range Intended patient population Laboratory location Applicable regulatory or accreditation requirements Validation parameters to be evaluated

Examples:

This validation applies to serum glucose testing performed on the XYZ-500 Chemistry Analyzer using ABC reagents in the Clinical Biochemistry Laboratory. The study includes precision, accuracy, linearity, reportable range, method comparison, carryover, and reference interval verification.

Step 2: Review Applicable Standards and Manufacturer Information

Before designing the validation study, review all available documentation, including:

Manufacturer's Instructions for Use (IFU)

Performance claims

Scientific literature

CLIA guidelines (where applicable)

ISO 15189:2022 requirements

Regulatory requirements

Previous validation reports (if available)

This information helps determine which performance characteristics require evaluation and what acceptance criteria should be used.

Step 3: Prepare a Validation Plan

A validation plan typically includes: Purpose of the study, Scope, Responsibilities, Examination procedure, details Equipment and reagents, etc.

Performance characteristics to be evaluated Number and type of samples, statistical methods, Acceptance criteria, Risk assessment, Documentation requirements, Timeline Preparing a validation plan helps ensure consistency and prevents important activities from being overlooked.

Step 4: Define Acceptance Criteria

Acceptance criteria should be based on: Manufacturer's specifications, Clinical requirements, Biological variation (where applicable), Regulatory expectations, Laboratory quality objectives,

Examples:

Bias ≤ predefined limit

Precision (CV%) within acceptable range

Correlation coefficient (R²) ≥ required value

Recovery within acceptable percentage

Linearity meeting predefined limits

Note: Acceptance criteria should be documented before the validation begins to avoid bias.

Step 5: Select Validation Parameters

Not every examination procedure requires assessment of every validation characteristic. The laboratory should evaluate only those characteristics relevant to the intended use.

Common validation parameters include:

Accuracy

Precision (Repeatability and Intermediate Precision)

Linearity

Trueness (Bias)

Analytical Measurement Range (AMR)

Limit of Detection (LoD)

Limit of Quantification (LoQ)

Analytical Sensitivity & Analytical Specificity

Carryover

Recovery Reference Interval (if applicable)

Measurement Uncertainty (where appropriate)

Step 6: Select Samples and Quality Control Materials

The reliability of a validation study depends heavily on the quality of the samples used, sample should Be stored and handled appropriately.

Step 7: Perform the Validation Experiments

Once the validation protocol has been reviewed and approved by laboratory management, the validation study can begin. The study must be performed exactly as described in the approved protocol to ensure reliable and reproducible results.

Important instruction include:

Follow standard operating procedures (SOPs).

Use trained personnel.

Ensure instruments are calibrated and maintained.

Use validated reagents.

Record all observations.

Repeat testing where required.

Precision Study

Test multiple replicates.

Perform testing over several days.

Calculate:

Mean

Standard deviation

Coefficient of variation (CV%)

Accuracy Study

Compare results with:
Reference methods

Certified reference materials

Peer laboratory results

Calculate:

Bias

Percent recovery

Correlation

Linearity Study

Analyze samples across the analytical measurement range to confirm that measured values are proportional to analyte concentration.

Detection Capability Determine:

Limit of Detection (LoD)

Limit of Quantification (LoQ)

Carryover Study

Evaluate whether high-concentration samples influence subsequent low-concentration samples.

Step 8: Analyze and Interpret the Data

After completing testing, analyze the collected data using appropriate statistical methods.

Common statistical analyses include:

Mean

Standard deviation

Coefficient of variation (CV%)

Step 9: Review Against Acceptance Criteria

The validation is considered successful only if every required performance characteristic meets the predefined acceptance criteria.

Accept

All criteria satisfied.

Conditional Acceptance

Minor deviations with documented justification.

Reject

Performance does not meet laboratory requirements.

Note: If acceptance criteria are not met, corrective actions should be taken before implementation.

Step 10: Document the Validation Study

ISO 15189:2022 requires laboratories to maintain documented evidence of validation activities.

A validation report should include: Method description, Equipment used, Reagents, Personnel involved, Validation protocol, Sample details, Statistical analysis Results, Deviations, Acceptance criteria and Final conclusion.

Once the validation study is completed, obtain approval signatures from the designated authorities and document the implementation date. Maintain complete, accurate, and traceable validation records, and retain all documentation in accordance with the laboratory's document control and record retention requirements as specified by ISO 15189:2022.

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Implementing ISO 15189:2022 requirements, conducting validation studies, preparing documentation, and achieving accreditation can be challenging without the right expertise.

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