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Section 1: Introduction and Background

1.1 Introduction

In June 2004 an incident occurred in a Trust in Northern Ireland. The failure to decontaminate adequately an endoscope raised concern about the possible risk of exposure of patients to blood borne virus infection. The incident resulted in a patient notification exercise being undertaken and prompted a review of endoscope decontamination throughout Northern Ireland ( NI).

The review raised concerns about decontamination procedures in a small number of endoscopes (25 out of more than 1000) that were in use in four NI Trusts. Endoscopes for which concerns were raised were withdrawn from service.

A UK Task Force and UK Expert Advisory Group led by the Health Protection Agency ( HPA) was established to support the investigation of the NI incident and the wider UK and international implications. The Expert Group considered that the deviations from recommended decontamination practice, identified in NI, constituted a very small risk, however, they recommended to the NI Department of Health, Social Services and Public Policy ( DHSSPP) that a patient notification exercise be undertaken in some cases, depending on the nature of the decontamination failure identified.

Discussions between the Scottish Executive Health Department ( SEHD), NHS Quality Improvement Scotland ( NHSQIS) and Health Protection Scotland (formerly SCIEH) resulted in the formation of a Scottish Action Group ( SAG) to oversee any actions resulting from the NI incident. This included agreeing the question set, based on those used in the NI review, for a review of endoscope decontamination practice in Scotland. The development of the endoscopy decontamination assessment tool ( EDAT) was undertaken by HPS and funded by NHSQIS.

Various communications were issued by all the UK Health Departments highlighting the risks from inadequate decontamination of endoscopes. In, Scotland, a Hazard Notice (HAZ(SC)04/05) (see Appendix 1) was issued on 25 June 2004 which instructed that an immediate review and assessment of all endoscope reprocessing facilities be undertaken and where deficiencies in processes were identified, implicated endoscopes be withdrawn from use until the local infection control team advised on adequate decontamination. Any concerns for public health were to be reported to the local Consultant in Public Health Medicine CPHM ( CD& EH).

The hazard notice was followed, in August 2004 by a letter from the Chief Medical Officer [CMO(2004)16] (Appendix 2) requiring that a review be undertaken. The review was intended to highlight any deficiencies in line with the earlier reviews undertaken locally in response to HAZ(SC)04/05 and to provide an evidence base for the development of any control measures required to reduce the potential risk of transmission of infection from endoscopic procedures.

Endoscopes are complex devices and their decontamination presents many challenges. The contribution made by endoscopy staff and their professional bodies, endoscope manufacturers and others in developing on-site reprocessing of these devices is noteworthy. In recent years, improvements in design and performance of endoscope washer disinfectors, the establishment of purpose-built facilities and specialist staff trained in device decontamination and the implementation of decontamination guidance and standards under the Medical Device Regulations have all impacted on the service overall. Previous reviews of bronchoscope decontamination ^1,2 indicated that national guidelines on good practice were not widely followed. The data generated from this review are intended to provide a benchmark on which to plan and implement improvements in decontamination against best practice guidance, to address the local needs of this reprocessing speciality and minimise further those incidents, which have led to public health concerns.

1.2 Risk of infection associated with endoscopy

The Expert Advisory Group of the UK Task Force carried out a literature review (forwarded for publication) which indicated that endoscopy carried a very low risk of transmission of blood borne viruses. The look back exercise in NI did not identify any cases of transmission of blood-borne infection ³. Reported transmission of blood borne viruses is extremely rare - only 5 published cases ^4,5,6,7 were identified anywhere in the world.

It appears from the literature that overall infection transmission at endoscopy is rare. Salmonella, Pseudomonas and mycobacterial species are reported to be the most common micro-organisms transmitted ⁸. It is recognised, however, that a review is likely to underestimate the number of infections occurring and there are no well designed prospective studies ⁹.

The British Society of Gastroenterology ( BSG), in their guidelines ¹⁰, state that "any patient must be considered a potential infection risk, and each endoscope and device must be decontaminated with the same rigour following every endoscopic procedure". Few data exist as to the absolute risk of transmission of infection from patient to patient at endoscopy. The BSG guidelines ¹⁰ further state that "estimating the infection risk is difficult for several reasons: complications such as septicaemia following ERCP may be due to the induction of endogenous infection as opposed to the endoscope being a vehicle of infection. Additionally the onset of infections complicating endoscopy may be delayed until after the patient has been discharged home following their procedure. There is also the potential for transmission of infective particles with very long incubation periods (v CJD for example)".

Improper cleaning and disinfection procedures, contamination from automated washers and inability to decontaminate complex channel and valve systems using standard disinfection techniques were cited in published reports as the main reasons for transmission of infection ^8,10. Indeed, it has been reported that " To date, all published episodes of pathogen transmission related to gastrointestinal endoscopy have been associated with failure to follow established cleaning and disinfection/sterilization guidelines or use of defective equipment ^9.

It is well established, therefore, that endoscopy carries a low (probably underestimated) risk of infection. In virtually all cases, the diagnostic and therapeutic benefits of endoscopy will far outweigh the risk of infection. Compliance with best practice guidance is essential if healthcare providers wish to keep the risk low and avoid legal liability for any adverse events following endoscopy.

1.3 Endoscopes and their use

An endoscope is an instrument that is used to obtain a view of the interior of the body. Use of endoscopes has increased in recent years for both diagnostic and therapeutic procedures.

Flexible Fibre-optic or Video Endoscopes are optical instruments that transmit light and carry images back to the operator via coherent bundles of very fine glass fibres, sheathed in an impervious protective covering of, for example, PVC, that forms a hermetic seal. A typical endoscope consists of a control head, a flexible shaft and a manoeuvrable end tip. The instrument is often long and complicated in design with channels for the introduction of operating instruments (also used for the removal of tissue) and suction channels used to clear the operative field. An 'umbilical' cord connects the head of the instrument to a light source. Air, water and suction channels are also contained within this cord (see Figure 1). The complicated design poses significant challenges during use, decontamination and storage. Some designs are incompatible with the instrument being submerged during cleaning and all are intolerant of minimum temperatures required for thermal disinfection.

Figure 1: Flexible fibre-optic endoscope

Rigid Endoscopes are also optical instruments but they are non-flexible, made of surgical stainless steel (see example at Figure 2). They can be designed for either high ( e.g., steam) or low ( e.g., chemical, ethylene oxide) temperature sterilization methods.

Figure 2: Rigid endoscope

Endoscopes are used routinly in many aspects of patient care, for example, in the gastro-intestinal tract for diagnosis and treatment of ulcers, cancers, strictures, or bleeding sites. They are found in most clinical settings including operating theatres, endoscopy suites, out patient clinics, wards, intensive care units, accident and emergency departments etc.

Endoscope is a general term. More precise names are given to endoscopes for viewing specific parts of the body, for example,

• gastroscope: to view the oesophagus, stomach and upper small intestine.
• colonoscope: to view the large intestine.
• bronchoscope: to view the air passages to the lungs.
• cystoscope: to view the urinary bladder.
• laryngoscope: to view the larynx.
• nasopharyngoscope: to view the nose and related cavities.
• arthroscope: to view inside joints such as the knee joint.

1.4 Endoscope decontamination

Endoscopes and their accessories are classified as medical devices under the Medical Devices Directive ¹¹. It is an essential requirement of this directive that devices and manufacturing processes be designed to eliminate or reduce as far as possible the risk of infection to the patient, user and third parties. The level of decontamination required for each endoscope will depend on its intended use. The Spaulding Classification System ¹² may be used to determine the appropriate decontamination level (see Table 1).

Table 1 Spaulding Classification Applied to Endoscopy ¹²

For the purpose of decontamination endoscopes can be divided into two types; those that can be terminally sterilized through a steam sterilization process and those that are heat sensitive and can only be disinfected or sterilized using low temperature liquid chemical or gaseous methods. These usually correspond with rigid and flexible endoscopes, respectively. Endoscopes can also be divided into those with channels and those without e.g., ENT endoscopes used for intubation have no channels. The manufacturers of endoscopes are required to provide information on the appropriate processes to allow reuse of equipment, which they supply.

Endoscope decontamination is a complex process involving a series of key stages, starting in the clinical unit, including pre-cleaning, cleaning, disinfection, inspection, sterilization, transport and storage, as necessary. Figures 3, 4, 5 & 6 show model endoscope decontamination process maps.

There are a number of aspects of endoscope design that affect decontamination. These include:

• length/narrowness of channels, especially elevator channel;
• interconnection between channels (requiring use of a channel separator for effective cleaning/disinfection);
• ease with which even unused channels may be contaminated with body fluids due to the need to inflate the site to be investigated;
• need in all cases for flushing of channels before disconnection from the endoscopy machine;
• need for manual cleaning as a precursor to automated cleaning;
• design of valves.

Figure 3 ENDOSCOPE DECONTAMINATION LIFE CYCLE - OVERVIEW

Figure 4 ENDOSCOPE DECONTAMINATION PROCESS POST-CLINICAL ACTIVITY IN CLINICAL AREA

Figure 5 DECONTAMINATION AREA: CLEANING AND DISINFECTION

Figure 6 DECONTAMINATION AREA: POST-CLEANING AND DISINFECTION ACTIVITY

For decontamination to be effective, all the process stages need to be conducted correctly, with controls and monitoring in place. The decontamination location, facilities, equipment, process management, and the policies and procedures employed all influence the achievement of acceptable standards.

Simple visual inspection of an endoscope before use cannot provide assurance of the efficacy of the decontamination process. Each process is subject to a number of critical variables and assurance of efficacy comes from control of these. Manual processes have limited control and rely on the training of the operator and strict adherence to agreed procedures to provide any degree of consistency.

Endoscope washer disinfectors ( EWD), in contrast, can be controlled automatically by programming with the pre-set variables essential for each stage of the operating cycle. Available EWD cycle stages should include; automatic leak testing (otherwise this has to be carried out manually prior to processing), cleaning (which may include several stages), disinfecting, final rinsing and drying. The automatic controller of the EWD checks the attainment of the pre-set variables, ensures reproducibility during each subsequent cycle and provides verification that the required standard is consistently achieved. This is the basis of 'validation' i.e., 'a documented procedure for obtaining, recording and interpreting the results to establish that a process will consistently yield product ( i.e., an appropriately decontaminated endoscope) complying with predetermined specifications'.

The selected endoscope disinfectant to be used must be validated for its intended use; this is usually done by the disinfectant manufacturer. Compatibility of the disinfectant with both endoscopes and EWDs must be established and this information must be provided. Some formulations and types of disinfectants can have a deleterious effect on the materials used in endoscopes and EWDs.

The principles of validation encompass the total decontamination process including equipment specification, manufacture, installation, performance testing and maintenance. Detailed performance requirement specifications for EWDs are given in the draft EN ISO 15883-1 ¹³ and -4 ¹⁴ and in Scottish Health Technical Memorandum 2030 ¹⁵.

The terminal disinfection process for flexible fibre-optic endoscopes results, in most cases, in a device, which is not packaged and protected against recontamination. Therefore the decontamination process should be undertaken close to the point of use of the endoscope and care taken to transport it without compromising its decontamination status.

There should be systems in place to track all endoscopes and endoscopic equipment through the decontamination process and to the patient on whom devices have been used. This information is needed to exclude an endoscope or potentially inadequate decontamination process as a source of cross-infection in an investigation of healthcare associated infection. It is also important for contact tracing when possible endoscopic transmission of disease is being investigated. NHS MEL (1999)65 ¹⁶ requires that systems should enable the rapid tracing of endoscopes, to avoid the risk of all endoscopes of a similar type needing to be quarantined and possibly destroyed in the event of a v CJD related incident.

At present, in Scotland, the facilities in which endoscope decontamination is undertaken fall into three broad, but not mutually exclusive categories ¹⁷:

• Central decontamination units ( CDUs) (also known as Sterile Service Departments) where the instruments from acute services clinical areas and sometimes also primary care services, usually from within one NHS Board area, are reprocessed. Generally thermal decontamination methods are utilised but cold decontamination methods appropriate for thermo-labile devices may be undertaken in some smaller units sited adjacent to clinical areas.
• Endoscopy re-processing units ( ERU) that are specifically intended to re-process only flexible, thermo-labile, usually fibre-optic, endoscopes and their accessories. Liquid chemical disinfectants are used to achieve high level terminal disinfection. Endoscope washer-disinfectors (also referred to as automatic endoscope reprocessors) are used. The ERU may serve more than one clinical unit.
• Local decontamination units ( LDUs) are, for example, ward, operating theatre or clinic based facilities where only the endoscopes used within that clinical area are reprocessed.

1.5 Decontamination standards and guidance

The national standards body, the British Standards Institute, publishes performance specification and testing standards for decontamination equipment and processes. There are also many sources of guidance on the decontamination of endoscopes published by expert and professional bodies in the form of best practice guidance. There is good agreement between these documents on the key elements of good practice. The key indicators cited in this report were abstracted from one or more of these documents which are listed below:

• The Medical Devices Agency ( MDA) (which has now been incorporated in the Medicines and Healthcare products Regulatory Agency) has published guidance on the Decontamination of Endoscopes (including MDA DB2002(05)) ¹⁸.

• The Joint Transmissible Spongiform Encephalopathy ( TSE) Working Group of the Advisory Committee on Dangerous Pathogens and the Spongiform Encephalopathy Advisory Committee Joint Working Group (ACDP/SEAC JWG) has published guidance on safe working and prevention of infection relating to CJD and related diseases (see

http://www.advisorybodies.doh.gov.uk/acdp/tseguidance/Index.htm) ¹⁹.

- A European/International standard on the requirements and tests for endoscope washer disinfectors, has been prepared by CEN ( WG 8 of TC102) and ISO (WG13 of TC198) as the fourth part of the 15883 series of standards ^13,14. The final draft has been agreed for progressing to final vote within CEN and ISO, before anticipated publication by BSi as a harmonised BSENISO standard under the Medical Devices Directive ¹¹ in 2006.

• NHSScotland Property and Environment Forum Executive published The Scottish Health Technical Memorandum 2030 'Washer-disinfectors' (2001) ¹⁵ this includes guidance on the choice, specification, purchase, installation, validation, periodic testing, operation and maintenance of endoscope WDs.
• NHS Estates published the Health Technical Memorandum 2030 'Washer-Disinfectors' (1997) ²⁰. This document is substantially similar to SHTM 2030 but includes details of the microbiological testing required.
• NHS Estates published a NHS Model Engineering Specification C32 'Automated Endoscope Reprocessors for Flexible Endoscopes' ²¹ in 2003.
• The Department of Health Medical Devices AgencyMicrobiology Advisory Committee published the " MAC Manual" Part 3, Section 2 that offers guidance on sterilization and disinfection of endoscopes ²².
• Guidance is also available from specialist professional bodies e.g. European Society for Gastroenterology ²³, British Society for Gastroenterology ¹⁰, British Thoracic Society ²⁴

To facilitate access to the recommendations and requirements of the current standards and guidance, Health Protection Scotland, on behalf of the SEHD 'Glennie Group', has collated information from the relevant reference sources in a single guidance document 'Endoscope Reprocessing: Guidance on the Requirements for Decontamination Equipment, Facilities and Management' ²⁵. Following consultation, this guidance is currently undergoing final revision prior to publication. The consultation draft remains available on the HPS Decontamination website.

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