Instrument, Method & Control Material Validation

Pathology

Regulatory requirements and standardization drive the need for documented instrument, method and control material validations. The Quality Circle, part of the Total Quality Management (TQM) system, consists of four parts: Quality Management Plan, Quality Control (QC), Quality Assurance (QA) and Quality Improvement. Validation is a component of the QA section of the Quality Circle.

In a 2010 study in the Archives of Pathology & Laboratory Medicine¹ it was stated that rework in a large, academic anatomic pathology laboratory could cost as much as $540.00 per day and the cost for H&E stained slides could rise to $18.00 per slide; advanced stains such as immunohistochemistry (IHC) could cost as much as $50.00 per slide. Standardizing histology laboratory practices, such as instrument, method and control material validations, will drive down workflow defects, reducing patient anxiety and laboratory stress.

Acquisition of Instrumentation

According to CLSI-31A Vol. 29 No.11-A Laboratory Instrument Implementation Verification and Maintenance, Approved Guideline, a successful validation implementation begins before the actual acquisition of the instrument. It is recommended that the ðlaboratory consider the skill levels of the laboratory personnel and in-house or outsourced service engineers, the laboratory conditions, remoteness of the laboratory for service and delivery. The laboratory should assess all electrical, water and safety requirements for both maintenance and operation when placing the instrument into the laboratory. Ensure that the laboratory checks all applicable federal, state and local regulatory requirements prior to beginning any validation.

Responsibilities of Personnel

To ensure smooth implementation, it is crucial that all essential personnel be aware of their responsibilities (Table 1.1, Laboratory Instrument Implementation, Verification, and Maintenance: Approved Guideline CLSI GP31-A, Vol. 29 No.11).

Function Checks

In addition to preventative and corrective maintenance of testing equipment and instruments, the laboratory must develop specific guidelines for function checks (operational verification). Some instruments may only require a function test (e.g., tissue floatation water bath or slide drying oven) and not require an official instrument validation process be performed, while other instruments require both function checks and instrument validation (e.g., tissue processors and slide stainers). All function checks must be documented.

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CLIA’88 requires that equipment, instruments or test systems developed internally or those without manufacturer’s guidelines for function checks must define a function check protocol to ensure accurate and reliable test results and reporting that must be conducted before testing patient samples.

The steps to developing a function check should include verifying the intended ðfunction of the piece of equipment. Establish the parameters for function checks per manufacturer’s recommendations and consider the requirements for proper functioning of the instrument (e.g., temperature, humidity), mechanical checks and recommended frequency. Establish and document the initial baseline as well as any subsequent periodic function checks. Upon completion of the function checks ensure that the supervisor and laboratory director or designee approvals are obtained.

Instrument Validation

The laboratory must demonstrate that an instrument performs comparably to the manufacturer’s established performance characteristics for accuracy, precision and reportable range of test results. Instrument validations must be performed any time a new instrument is installed, added, relocated and when a demo/loaner instrument is placed in the laboratory. All validations must be performed prior to testing patient samples.

To perform an instrument validation, establish the test sample size and test conditions. The lab may use previously tested samples if available. Compare the previously tested sample’s results to results obtained with new instrument validation. Document results and corrective actions, if necessary. Repeat testing on a series of consecutive days or runs to establish reproducibility; when the testing is completed obtain lab director or designee approval. This process may be repeated on relocated instruments, demo/loaner instruments as well as instrument to instrument validations.

Method Validation

A method validation is required when a new test or method modification is introduced into the laboratory. The laboratory must demonstrate that a new method or modification performs comparably to or better than the old method of testing. An example may include when a new staining and/or tissue processing platform is introduced into the laboratory. To perform a method validation, write a method validation protocol, select the number of specimens from previously tested samples. Perform testing using the new method, document the results and compare to the previously tested results, document any failure and repeat if necessary. Obtain the lab director or designee approval and signature.

Control Material Validation

All control material obtained from vendors or in-house samples must be validated prior to being put into use with patient samples. It is best to use control material processed and cut per the lab protocols when possible. When using commercially purchased control material, the lab must stain a slide with the in-house protocol to validate that the stain shows the appropriate staining. The lab should stain the first and last slide in a series to ensure that the area of interest is still present. Document the validation and obtain the lab director’s or designee’s approval and signature. Organized storage of control material blocks is a must. Never pull control blocks that have not been validated for use. Keep all control material validations for two years.

Debra S. Siena is technical support manager, StatLab Medical Products; Kathleen A. Dwyer is director, Medical Quality Assurance AmeriPath Inc.

Reference

Muirhead D, Aoun P, Powell M, Juncker F, Mollerup J. Pathology economic model tool: A novel approach to workflow and budget cost analysis in an anatomic pathology laboratory. Archives of Pathology & Laboratory Medicine 2010;134(8):1164-1169.