Laboratory Accreditation : the basis for confidence

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CPA UK Ltd was formed by the main UK organisations of laboratory professionals to operate a scheme of voluntary accreditation for laboratories. Laboratories participating in the scheme are inspected every four years and have to renew their registration every year, confirming that they are continuing to operate according to strict guidelines. Although the scheme is voluntary, the majority of UK clinical laboratories are currently accredited by the scheme, and the phrase 'CPA accredited laboratory' is a guarantee that the laboratory has been inspected and approved as a provider of results which meet accepted standards. More details can be found on the CPA website, which lists all currently accredited laboratories.

Four particularly important areas for inspection are external quality assessment, internal quality control, standard operating procedures and personnel training.

External quality assessment:

Laboratories performing tests on clinical samples participate in External Quality Assessment (EQA) programmes. In these programmes, an outside agency checks on the accuracy of a laboratory's test results by sending test specimens to be analysed. The outside agency knows the results of the tests- the cholesterol level, for example - but the laboratory does not. The laboratory must test these specimens in the same way it would test specimens normally and return their result to the EQA co-ordinators. The outside agency uses these programmes to assess the laboratory’s ability to deliver consistently accurate results, and laboratories with performance problems will receive advice and help to rectify any difficulties. CPA inspectors verify that the laboratory shows acceptable performance in approved EQA schemes.

Internal quality control:

To ensure that the results being issued by the laboratory are correct, 24 hours a day, 7 days a week, clinical laboratories test 'control' specimens alongside test specimens from patients. The laboratories know the result of the control specimens which act as a built-in check on the process of analysis, which in many cases is carried out on automated equipment. The control specimens contain both high and low values of the test being measured, to make sure that the analyser or procedure is operating correctly across the range of concentrations the patient specimens may contain. If the control results vary from the known quantities, laboratory staff will immediately know that there is a problem and take action to resolve. Laboratory inspectors also examine these records as part of their evaluations to ensure the action of the laboratory scientists is appropriate.

Standard Operating Procedures:

Every test or process carried out in a laboratory must have a Standard Operating Procedure, which is a defined way of performing a specific course of action. Standard Operating Procedures help to ensure that every process is carried out consistently and accurately each time, Inspectors ensure that all Standard Operating Procedures are accessible, regularly reviewed and up-to-date.

Education and Training:

There are many roles to fulfil in a laboratory, and both the professional organisations and the statutory bodies which undertake registration spell out the requirements for education, fitness to practice and training of laboratory personnel.

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