Quality Control In Histopathology

Quality Control in Histopathology Bello J.M.

Outline Introduction  What is Quality Control?  Related Terminologies  QC as it relates to Histopathology 

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Variables that affect the quality of results How to achieve Quality Control General recommendations

Conclusion

INTRODUCTION Maintaining a high standard of care in medicine is important both to the public and to the medical profession.  The processes by which these standards are monitored and maintained have been given different labels depending on their geographical and political contexts.  Such terms include Medical Audit, Clinical Audit and Quality Control 

Introduction ctd 

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The following comments are heard far too often in laboratory medicine:  „„This result can‟t be right!”  “The laboratory messed up again!‟‟ Clinicians often attribute many patient results that do not fit expected findings to laboratory error. The National Academics Institute of Medicine (IOM) in the U.S.A. estimates that approximately 44,000 to 98,000 deaths occur annually in that country alone due to medical errors.

Introduction ctd Some of these errors occur in the laboratory histopathology inclusive.  Error in clinical laboratories is any defect from ordering tests to reporting results and appropriately interpreting and reacting on these. 

What is QC 

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Quality Control - QC refers to the measures that must be included during each assay run (tissue processing) to verify that the test is working properly. It is a process or system for monitoring the quality of laboratory testing, and the accuracy and precision of results It involves routine collection and analysis of data from every test run or procedure Thus, QC allows detection of errors for immediate corrective action

Quality Assurance (QA)

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Quality Assurance - QA is defined as the overall program that ensures that the final results reported by the laboratory are correct. The aim of quality control is simply to ensure that the results generated by the test are correct. However, quality assurance is concerned with much more: that the right test is carried out on the right specimen, and that the right result and right interpretation is delivered to the right person at the right time

Quality Assurance vs. Quality Control 

Quality Control

A series of analytical measurements used to assess the quality of the analytical data (The “tools”)

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Quality Assurance

An overall management plan to guarantee the integrity of data (The “system”)

Quality control, Quality Assurance and Total Quality Management 

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Thus the terms QC, and Quality Assurance (QA) differ from each other in the degree of process and organizational involvement, which is overall and maximal in TQM. For all practical purposes, all these elements should be focused to  a) generate an accurate histopathology report and  b) enable easy retrieval and review if needed over a defined time period.

QC IN HISTOPATHOLOGY 

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The concept of quality control, which is deeply rooted in most other disciplines of laboratory medicine, is relatively young in the histopathology department. Assessment and implementation of quality control is more difficult in histopathology due to the inherent qualities such as  the lack of objective numerical data,  descriptive nature of reports,  subjectivity, individual judgment and bias,  non uniformity of reporting patterns, etc.

Variables that affect the quality of results The educational background and training of the laboratory personnel  The condition of the specimens  The controls used in the test runs  Reagents  Equipment  The interpretation of the results  The transcription of results  The reporting of results 

Variables that affect the quality of results 

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These variables can be grouped into three phases of operation which Quality control is traditionally applicable to. These are: 1) the pre-analytical phase, 2) the analytical phase and 3) the post-analytical phase

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The pre-analytical phase is related to sample collection, transport, accession and processing. The analytical phase is related to actually carrying out the test (manual/automated) The activities that follow (transmission of results, storage/disposal of samples, maintenance of test data, etc.) comprise the post-analytical part. In the departments such as clinical biochemistry, hematology and immunoassay where numerical data is obtained, methods for analysis of quality are well established. When descriptive reports are made, such an assessment becomes less simple though not unachievable

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A good quality histological section is the starting point of an accurate histopathology report. All the processes involved in generating the section may be grouped under the pre-analytical part. The analytical part concerns the interpretation of the slide and making an accurate diagnosis. The post-analytical part involves the generation and transmission of the histopathology report, storage/disposal of samples, slides and blocks and proper retention of test results.

Pre-analytical aspects All processes involved up to the submission of stained slides for analysis are grouped under pre-analytical.  Newer models for the pre-analytical phase also include aspects like patient satisfaction with the collection process, professional staff satisfaction with arrangements made by the laboratory towards sample collection and transport 

Preanalytical ctd 

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Majority of errors in the laboratory (histo lab inclusive) relate to the pre-analytical phase. A lot has been said and written about the importance of primary fixation and the choice of fixatives for specific histopathology investigations. It is the responsibility of the lab to ensure that documented instructions containing relevant information are made available at all points of specimen collection. Correct patient identification by a unique accession number that is traceable to the specimen and report all through the process is of prime importance

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Similarly, wrong identification of anatomic location as well as laterality of biopsy (right/left) are common errors that should be avoided. It would be worth while for the laboratory to design its own "referral form" for histopathology and make it available to all areas of sample collection. This form should provide space for entry of the relevant clinical data.  It may be useful to insert check boxes for better clinician compliance. Dialogue with the clinician about the importance of properly filled forms may be needed and whenever clinical data is not provided, the laboratory should take the initiative to extract relevant data either from the treating physician or hospital files.

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Other areas of error in the pre-analytical phase include lost specimens, inadequate volume, size, gross description, gross sampling, erroneous measurements, extraneous tissue (floaters), improper sections/inadequate serials, poor staining and mounting quality, etc.

Steps on how to achieve proper control of the pre-analytical process 1.

Standard procedures for sample accession, identification, acceptance/rejection, gross examination and sampling and all the steps that follow must be documented. This SOP should be written in simple language that can be understood by all and should be available at the workplace and all technical staff should be aware of its contents.

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Planned changing of chemicals used for processing based on the number of tissues passed through. This schedule will prevent under processing and unnecessary rework and loss of tissue. The same also applies to the deparaffinization, staining, dehydration and clearing steps for sections.

Steps on how to achieve proper control of the pre-analytical process 3.

Usage of controls for routine and special stains daily as a routine is strongly recomended. For routine H & E staining, the laboratory may identify one tissue block with a good mixture of hematoxyphilic and eosinophilic tissue (cervix, fibroadenoma, etc.) as a control.

4. The microtome should be of good quality and serviced regularly. Periodic calibration of the micrometer should be made to ensure consistency of section thickness.

5. Care should be taken not to induce tissue artifacts due to improper processing, sectioning, staining and mounting.

6. The label affixed on the stained slide should be of an appropriate size so that it does not project beyond the slide or cover the tissue sections. 1.

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The identification should be legible and should ideally carry the name of the laboratory. Using bar code labels, one can incorporate demographic data such as the name of the laboratory, the name of the patient, the laboratory ID number and the date.

Post-analytical aspects 

The traditional laboratory approach to the postanalytical phase involves    

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report generation without transcription errors, report transmission/dispatch to the right person(s), storage of reported material as well as reported data and safe disposal of specimens thereafter.

Newer models include billing issues, patient safety issues (reporting of critical results), turn around time (TAT) and general customer satisfaction (wait times), etc.

Monitoring of TAT is of vital importance and laboratories should strive to achieve the goal of signing out the majority of cases within 48 hours of receipt of the specimen.  The use of microwaves may assist in improving the TAT especially for small biopsies.  The TAT of frozen sections should also be monitored and potential bottle-necks should be eliminated.  The retention period for specimens has always been a subject of debate and national guidelines for this are warranted. 

Analytical aspects 

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Unlike in other disciplines of laboratory medicine, assessment of analytical aspects in histopathology is not easy given the subjectivity of the reports. Error detection and avoidance in histopathology has been written about very often. Various modes of internal audits have been described and recommended, each with their advantages.

Recommendations for analytical phase   

Intra-departmental consultation (review of selected cases by colleagues) Comparison with other reports (frozen/cytology/histopathology) Random case review (blinded re-reporting of random cases)  

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By the same person (check for precision) By a different person (check for accuracy)

Hierarchical form of reporting Using clinicopathological meetings to ensure diagnostic accuracy and maintain good clinical liaison; audit diagnostic changes at these meetings

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Audit workload levels to ensure an even distribution of the departmental caseload where possible Utilize recommended reporting guidelines and templates, wherever available, with audit of compliance External consultations (may need to be done more often) Review by experts Participation in continued medical education (CME) programs

CONCLUSION Error reduction and improved quality are essentially two names for the same goal; you can‟t have one without the other.  Probably the most important factor for error reduction is a commitment by the team (pathologists, scientists technologists, etc.) to reduce errors/improve quality. 

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