Variant Creutzfeldt Jacob Disease (vCJD)

The potential for vCJD to be passed onto new patients via endoscopes that had breached mucosal barriers has been a concern for a number of years and the basis of a great deal of study since the disease was identified in the mid 1990s. Fortunately it has not turned out to be the catastrophic disease first feared, but none-the-less has continued to be of great concern in neurosurgical and endoscopic interventions since then. This is not least because the prion – the identified cause of vCJD – is very difficult to remove from surgical instruments and endoscope channels. The work of the Advisory Committee on Dangerous Pathogens – Transmissible Spongiform Encephalopathy Subgroup (ACDP-TSE) relates to continuing research outcomes and an ongoing review of the risks of the disease and its’ transmission. Recommendations for safe practice which relate to aspects of care on which they are experts, are identified via a series of different documents and the specialised decontamination and endoscopy annexes are available to anyone who may have difficulty or a query.3

Quality assurance

The parameters and standards for safe care in endoscopy are managed by the Joint Advisory Group of the British Society for Gastroenterology across the UK, which accredits each of the many units throughout the country. The Group is strict and will close a unit down temporarily until issues are resolved. The group’s well known standards of care are respected nationally and internationally.

Each endoscopy unit is reviewed regularly for many different elements under four domains: l Clinical quality l Quality of the patient experience l Workforce l Training.

Endoscopy services are asked to provide evidence to support their applications for accreditation and demonstrate compliance with the standards. The preface to the standards4

reports that they have been

developed to reflect current expectations and to reduce the burden of evidence collection for accreditation. The standards helpfully cross reference their standards to criteria which the Care Quality Commission uses in order to an have oversight of the quality of care in hospitals – including the endoscopy service. In other countries in the UK, other

regulators have their own standards for inspection and audit.

Standards for decontamination

Health Technical Memorandum (HTM) 01-06 (5) has been updated to take account of new guidance from the Advisory Committee on Dangerous Pathogens – Transmissible Spongiform Encephalopathy Subgroup’s further guidance on general principles of decontamination. The document cites: “For endoscopes, the bedside clean should take place immediately after the procedure has been carried out, and it is recommended that the endoscopes should be manually cleaned according to the manufacturer’s recommendations and passed through the Endoscope Washer Disinfector as soon as possible after use.”

The guidance also states: “A routine test for washer disinfectors could be developed to measure the cleaning efficacy at validation and routine testing, such as daily or weekly tests. This method could be based on a process challenge device system that will monitor the optimised wash cycles; the results must be quantifiable and objective.” The update of the HTM, which used to be in the Choice Framework Documents group, is a dynamic process reflecting evolving standards and technologies. There are five parts of the HTM dealing separately with policy and management, design and installation, operational management, validation and verification and testing methods. It clearly states that the document does not cover endoscopes which are used to examine sterile tissues such as choledochoscopes.

The crux of the whole decontamination process is that the design of a flexible

The crux of the whole decontamination process is that the design of a flexible endoscope makes it extremely difficult to clean, with difficult access to long fine lumens.


endoscope makes it extremely difficult to clean, with difficult access to long fine lumens. It is essential during the cleaning process that every lumen is cleaned and reprocessed after use, even if the channels were not used in the examination. Endoscopes are also thermo-labile and thus have to be put through a specialised validated process which will not harm any component parts. Validation of the cleanliness of an endoscope once it has been through its cleaning and disinfection process is undertaken via a protein test. Ninhydrin is the current usual testing enzyme but is deprecated by ACDP in Annexe C.6

They suggest that

alternative technologies are sought in order to detect residual proteins on the internal surfaces of endoscopes after processing. There is a relatively new international standard which requires that the endoscope, once it has been through its disinfection process, and it needs to be stored or reprocessed before use on a patient. New storage facilities with positive pressure and hepa-filtered air are available or following processing in some endoscope washer disinfectors (EWD) some scopes can be stored in the cassettes in which they were processed. This has extended the shelf-life of a processed endoscope and many hours of re-processing. The drying process involved in both systems prevents the development of biofilms which can lead to bacterial development. This has facilitated the transport of endoscopes to off-site decontamination facilities. Immediate cleaning following patient use, as identified by the ACDP and now the HTM standard, usually involves using a detergent which is compatible with the disinfectant chemistry used in the washer disinfector. All channels should be flushed through, possibly using a pump system, and as much soil and contamination removed, before moving it towards the EWD for its full decontamination processing.7

The importance of documentation

As with any patient care procedure, detailed notes need to be kept to account for the tests

MAY 2019

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