The Decontamination of Flexible Endoscopes requires several important stages to remove soiling prior to disinfecting. The decontamination of flexible endoscopes must be undertaken by trained dedicated decontamination technicians. They are often processed in dedicated endoscopy decontamination areas with defined clean and dirty areas within an endoscopy suite or in a central decontamination facility.
Like Ultrasound Probes, flexible endoscopes are heat liable and cannot be processed using standard instrument washer disinfectors but are processed in an Endoscope Washer Disinfector EWD. Furthermore, they incorporate a complicated set of internal channels which must also be subjected to the full disinfection process.
What is a Flexible Endoscope
Flexible endoscopes are devices used for minimally invasive procedures such as Gastroscopy, Colonoscopy, Cystoscopy or Bronchoscopy procedures. Flexible endoscopes are complex medical devices which are easily broken. Extreme care must be made during clinical procedures, decontamination process and subsequent storage or transportation.
The working part referred to as the insertion tube is graduated and contains several internal channels and angulation control wires to control the distal end angle.
The endoscope is controlled via the control section, here the endoscopist can adjust the angle of the distal end to aid navigation and to provide clear field for examining the area being scoped. The endoscopist can also control the suction and air/water channels.
On the reverse side of the control section, access to the biopsy channel is possible. Here the endoscopist can obtain biopsies or undertake small procedures such as removing polyps. During the decontamination process a channel separator is used to ensure fluid is not passed down the air channel but is diverted down the water channel, following the decontamination process the channel separator is removed.
During an endoscopic procedure the endoscope is connected to a control stack via the connector block to allow connection to Light, Suction and Video/imaging.
Pre-Cleaning Flexible Endoscopes
The pre-cleaning of flexible endoscopes is the most important part of the process.
Following an endoscopy procedure, the endoscope is pre-cleaned using a bedside cleaning kit, this must be undertaken as soon as the procedure is completed to prevent any soiling adhering to the surfaces of the endoscope. A bedside cleaning kit contains an enzymatic detergent, disposable sponge, and a disposable pot to aid a bedside clean.
Following this initial bedside clean the endoscope is carefully placed in a suitable tray and returned for re-processing. Endoscopes are contained in a way to show they are contaminated to prevent any possibility of cross contamination during transit.
The importance of the Air Leak Test
During the initial clean, the scope is submerged into a pre-clean sink containing a suitable detergent. Before the endoscope is manually washed, an air leak test is performed to ensure that the integrity of the outer insertion tube is good. If there is damage to the insertion tube tiny bubbles and loss of pressure will be evident. If this occurs, then the endoscope is returned to the manufacturer for repair. This is important not only to protect the internal components from water ingress and further damage, but also to prevent cross contamination to subsequent patients.
Following a satisfactory leak test the internal channels are manually brushed using single use channel cleaning brushes. It is important to use the correct size brush, as endoscope channels differ in size. The ‘disposable cleaning brush set’ also contains a batch label which must be retained for traceability purposes, demonstrating that the endoscope was manually brushed.
Detergent is then manually syringed through the channels, alternatively, the endoscope is connected to an automatic pre-cleaning machine which automatically purges the endoscope with the correct volume of detergent. The flexible endoscope is then flushed and rinsed using clean water prior to the decontamination process.
High Level Disinfection
Flexible endoscopes are decontaminated through an endoscope washer disinfector (EWD). The EWD is a validated machine which performs an automatic leak test, followed by the cleaning stage, the disinfection stage, and the rinse stage. Finally, the endoscope is purged with filtered air to remove any residual water within the channels.
The standard UK chemistry used for high level decontamination of flexible endoscopes is peracetic acid. The EWD is carefully calibrated to measure the flow pressure in the various channels of each endoscope, if the flow pressure differs then the EWD will fail the cycle due to possible channel blockage, and endoscope will require further processing.
Types of Endoscope Washer Disinfectors EWDs
EWDs are designed in several different ways including multi-scope chamber, single scope chamber, pass through or top loader. Careful consideration should be made when designing an endoscopy decontamination facility to meet the service needs. Advice from authorising engineers specialising in decontamination (AED) can assist with design and ongoing endoscopy decontamination matters.
Storage and Transporting Flexible Endoscopes
Following decontaminating, the endoscope can be stored in a validated scope storage cabinet, depending on the manufacturer cabinet type and validation. Flexible endoscopes can be safely stored up to 30 days. If endoscopes are not stored in an ‘endoscopes drying storage cabinet’ they must be placed in a suitable tray and sealed using a disposable transport bag, the endoscope must be used within a 3-hour window. This is important due to potential microbial growth if there is residual water inside the endoscope.
It is possible to package endoscopes under vacuum or by introducing a nitrogen and carbon dioxide gas mixture (which is also used in the food industry). Endoscope packaging will allow longer storage conditions depending on the type of validation undertaken.
Sterilising Flexible Endoscopes
With developing technology, it is now possible to terminally sterilise heat liable flexible endoscopes. This is possible by utilising Low Temperature Vaporised H2O2 Sterilisers or Gas Plasma Sterilisers. Sterilising flexible endoscopes is necessary if the endoscope touches sterile tissue such as the bile duct or pancreatic duct, this procedure is referred to as an: Endoscopic Retrograde Cholangiopancreatography (ERCP) procedure. Some endoscopy decontamination facilities are moving towards terminally sterilising flexible endoscopes used during urology procedures as the bladder and ureter are sterile body cavity.
Naso-Fiberscopes
Naso-fiberscopes are much simpler in construction compared to standard flexible endoscopes. Here, with this type of endoscope there are no internal channels, however, thorough pre-cleaning, high level disinfection and final rinse is still required to prevent cross contamination of bloodborne pathogens such as Hepatitis B Virus (HBV). Another pathogen of concern is the Human Papillomavirus (HPV) which can cause cancer.
Manual & Semi Automatic High Level Disinfection
ENT Clinics should procure enough scopes to allow for central decontamination, where this is not practical a manual decontamination process must be adopted. The manual high level disinfection process includes using a pre-cleaning wipe, a high-level disinfection wipe (often Chlorine Dioxide) and a final rinse wipe. All stages of manual decontamination must be recorded for traceability purposes. Alternatively, Naso-fiberscopes can be processed using a semi-automatic process utilising UV light or Hydrogen Peroxide. However, the naso-fiberscope must be suitably pre-cleaned and rinsed when utilising semi-automatic disinfectors.
Hospital Technical Memorandum HTM 01-06 provides guidance on management and decontamination of flexible endoscopes.
