The Value of External Quality Assurance

Sue Smith

As a Senior BMS in a District General Hospital I have worked in Cytology for over 25 years, initially in Cervical Cytology and then Diagnostic Cytology. My laboratory is not a teaching hospital, and we don’t do anything out of the ordinary or unusual. This made it challenging for me to choose a subject for my first blog that I felt would be interesting.

This led me to think about a recent opportunity I had to attend the UKNEQAS CPT Annual meeting for participants of their EQA schemes which I found to be an incredibly valuable experience. 

The opportunity to share, listen, and learn from other labs, participants, and colleagues, with Diagnostic Cytology presentations on cell blocks, crystal analysis and troubleshooting staining techniques with a focus on quality, was a great update with some useful points. 

So with that in mind, I thought it would be useful to share a little more on the history and benefits of EQA and where further information, resources, or contacts can be found.

The World Health Organisation (WHO) defines External Quality Assurance (EQA) as “a system for objectively checking the laboratory’s performance using an external agency or facility”. 

The history of Cytology EQA schemes in England has been longstanding, beginning with the proficiency testing schemes developed for cervical screening in the late 1980’s and early 1990’s. 

Provision of EQA in Cytology falls into two categories – technical and interpretative, and proficiency testing is a form of the latter. I remember the dread of each circulation of the NHSCSP Proficiency Testing Scheme: a set of 10 slides screened independently by all screeners, BMS and Pathologists within a laboratory. 

Consensus reports enabled comparison of results with peers. In the UK, H&E staining and tinctorial staining schemes were developed as quality assurance mechanisms for technical aspects of laboratories. These utilise a set scoring criteria either for review of archive material or in-house staining of provided material, as per individual laboratory procedure. 

Subsequently technical schemes for cervical and diagnostic cytology were introduced. Similar provision of EQA schemes is provided by many establishments worldwide.

In the UK there is a requirement for participation in appropriate schemes for individuals and laboratories involved in Screening Programmes. 

In addition a robust laboratory quality management system also requires EQA covering the whole scope of the service or in situations where no EQA scheme exists, inter-laboratory comparison. This is a requirement for laboratories to be accredited to ISO15189 standards and is supported by the RCPath and IBMS.

As laboratories have developed newer techniques, EQA schemes are available across Europe and internationally, for immunocytochemistry, HPV detection and more recently cell block. 

As future progression moves toward digital solutions and AI, these may require some form of regulatory and quality assurance as well. A variety of interpretative schemes have been available for Pathologists reporting Histology for quite some time and there is now a scheme available covering the interpretation of Diagnostic Cytology open to BMS and medical staff.

The benefits of EQA are numerous in terms of safety, patient care, promoting quality and education. The loss of experienced cytology personnel in many laboratories following the move to HPV Primary Screening in the NHSCSP may have caused staff to feel isolated with possible skill reduction. 

EQA participation is a method of identifying performance which requires support to achieve improvement to fall into line with peers and should not be seen as punitive. Sharing of ideas and challenges can provide suggestions and direction for optimising protocols as well as avoiding professional isolation.

Within our department we have found participation in EQA useful, not only as a barometer of quality for technical procedures but also for trending failures and pointing to areas requiring improvement. 

For technical EQA schemes we have found in-house scoring prior to submission of material an excellent educational exercise, as well as providing CPD, training, measurement of interoperative variability and competency. Multiheaded microscopy reviews of cases enables discussion of techniques, expected results and criteria and is a driver for educational activities.

Comparison of EQA scheme results with in-house scores can help to identify drift of the laboratory or individuals. 

Results can provide objective evidence for corrective and preventative actions (CAPAs). When scores below our laboratory determined threshold are received this instigates investigation using a checklist approach. 

Possible issues include clerical errors, such as sending inappropriate material, equipment problems including lack of preventative maintenance and failures of the method or procedure. Alternatively low scores could highlight a training need or review of the method employed. 

Review of submitted material with feedback from the scheme organisers facilitates reflection on performance and directs corrective action. Interpretative EQA schemes are individually assessed, and in embracing digital technology, have allowed access to a wider participant base. 

Schemes such as these can be used as evidence of CPD and in appraisal and revalidation. 

Utilising EQA in this way, it can support and enhance a laboratory’s quality management system, facilitate meaningful improvement processes and develop best practices.

As a final note, the BAC website offers guidance and links on many subjects across Cervical and Diagnostic Cytology and offers advice through the Ask the Expert section which is publicly available irrespective of membership. 

Further resources are available through institutions such as the IBMS, RCPath and EQA providers, creating opportunities for discussion and providing support to all members.