Endoscope reprocessing
Endoscopes: pre-clean the unseen
Kerry Dolan provides an insight into the problem of biofilms and discusses why endoscope pre-cleaning is crucial for patient safety.
Pre-cleaning is a fundamental step in an endoscope’s reprocessing journey. The pre-clean begins at the bedside post-procedure and should be carried out immediately after the removal of the insertion tube from the patient. Failure to perform this simple task could pose a serious threat to patient safety due to the growth of potentially dangerous, invisible bacteria. Current UK guidelines recommend that
reprocessing flexible endoscopes with lumens is split into three different areas: 1. Manual cleaning – this includes brushing with a single-use cleaning device, rinsing, and exposing external and accessible internal components to a low foaming detergent, which is compatible with the endoscope. This procedure is unstandardised and relies on the competence of the endoscopy unit staff.
2. Automated cleaning – this is carried out in an automated washer system or endoscope washer disinfector (EWD) in which, cleaning can be measured.
3. Automated disinfection – followed by rinsing and drying the endoscope. This stage should
also be verified by a validation protocol in line with the basic testing requirements.1
Pre-cleaning an endoscope is a straightforward process – when the endoscope is removed from the patient after the procedure, the insertion tube is wiped with a sponge soaked in a detergent solution to remove any debris. Water and detergent should be sucked through the working channel to ensure that it is not blocked. In addition, the air and water channels (and any auxiliary channel) should be irrigated with detergent to clear any blood, mucus, or blockages.
Excess fluid should then be removed from all
the channels by flushing with air. Endoscopes are then placed into a secure container for the next stage of reprocessing. The importance of a timely pre-clean process helps to reduce the formation of biofilm and the possibility of drying.2
What is biofilm? Biofilm forms when bacteria sticks to surfaces in moist environments by excreting a slimy, glue-
like substance. Biofilm can be found underwater, underground, and above ground. It can grow on plant and animal tissues, and worryingly, on medical devices.3 Where there is a combination of nutrients,
moisture, and a surface, you are likely to find biofilm. Common examples of biofilm are dental plaque or pond scum. Biofilm is drug-resistant and potentially dangerous to patient safety as it is a major contaminant of medical devices. By reducing the formation and build-up of biofilm, patient safety is greatly improved. Pre-cleaning the endoscope immediately
after a procedure reduces the risk of biofilm formation and prevents any biofilm from drying on the scope. If this is not removed straight away, further reprocessing and even high-level disinfection may be ineffective. A simple way to explain biofilm is by using the porridge metaphor. Imagine eating a bowl of porridge in the morning, but you do not have the time to wash the bowl before leaving the house. The bowl sits on the countertop all day. On your return home, the bowl of hardened porridge residue is incredibly hard to remove under running water, even when scrubbing with a sponge. If the same bowl is placed into a dishwasher, sometimes this is not enough to completely remove the dried residue. If the bowl had been placed in the sink and soaked all day before going into the dishwasher, the porridge would be much easier to remove.4
Biofilm acts in
much the same way as the porridge residue, if we soak the endoscope immediately after use, it will be much easier to remove in the EWD. However, despite having these measures in place, reports of dirty scopes continue to emerge after they have been reprocessed. In a report by the FDA (Food and Drug Administration), in December 2023, a patient became ill with Salmonella following a colonoscopy procedure. It was found the same scope had been used on a further 17 patients before the facility’s infection control was informed. After investigation, the endoscope was sent for culture and quarantine testing and received a positive salmonella culture back
June 2024 I
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