CER Principles and Maintenance 2 — Questions and Answers
Question 1: Which parameter is most critical to monitor during automated endoscope reprocessing (AER) to ensure consistent disinfection?
- Water temperature only
- Cycle time, temperature, and chemical concentration together (Correct answer)
- The brand of detergent used
- The age of the endoscope
Correct answer: Cycle time, temperature, and chemical concentration together
AER efficacy depends on simultaneous control of cycle time, temperature, and disinfectant concentration as validated during machine qualification.
Question 2: What is the purpose of leak testing an endoscope before immersion in liquid detergent?
- To confirm the scope's optical clarity
- To detect breaches in the endoscope's protective sheath that could allow fluid ingress (Correct answer)
- To measure the bending angle of the insertion tube
- To calibrate the light source
Correct answer: To detect breaches in the endoscope's protective sheath that could allow fluid ingress
Leak testing identifies compromised seals or perforations before immersion so that fluid does not enter internal channels and cause irreparable damage.
Question 3: High-level disinfection (HLD) of flexible endoscopes is sufficient rather than sterilization because:
- Endoscopes are used only on healthy patients
- Heat-sensitive materials cannot withstand sterilization cycles and HLD eliminates all pathogens except high numbers of bacterial spores (Correct answer)
- HLD is faster and cheaper with no infection risk
- Regulatory agencies have not approved sterilization for endoscopes
Correct answer: Heat-sensitive materials cannot withstand sterilization cycles and HLD eliminates all pathogens except high numbers of bacterial spores
Semi-critical devices like endoscopes require HLD because they contact mucous membranes, and HLD kills all microorganisms except large numbers of bacterial spores, which pose minimal risk to intact membranes.
Question 4: When should the minimum effective concentration (MEC) of a high-level disinfectant be tested?
- Only when a new container is opened
- Before each day of use or per manufacturer instructions (Correct answer)
- Monthly by a certified laboratory
- Only after a reprocessing failure is reported
Correct answer: Before each day of use or per manufacturer instructions
MEC testing before each day of use ensures the disinfectant remains potent enough to achieve HLD throughout the workday.
Question 5: Which type of water is recommended for the final rinse step after high-level disinfection of endoscopes?
- Tap water at any temperature
- Sterile water, filtered water, or water meeting specific microbiological standards (Correct answer)
- Distilled water heated to 50°C
- Deionized water combined with 70% alcohol
Correct answer: Sterile water, filtered water, or water meeting specific microbiological standards
Sterile or microbiologically controlled water prevents recontamination of the endoscope from waterborne organisms like Pseudomonas during the final rinse.
Question 6: During manual cleaning of an endoscope, brushing of instrument channels should continue until:
- Five passes have been completed
- The brush emerges clean on both ends, indicating debris has been removed (Correct answer)
- Ten minutes have elapsed
- The channel no longer produces foam
Correct answer: The brush emerges clean on both ends, indicating debris has been removed
Visual inspection of the brush emerging clean from both ends confirms that gross debris has been mechanically removed, which is essential before disinfection.
Question 7: What does 'shelf life' refer to in the context of high-level disinfectants?
- How long a sealed container can be stored before opening
- The number of endoscope cycles an activated solution can support while remaining above MEC (Correct answer)
- The time between chemical manufacture and expiry of the raw ingredient
- How long a disinfected endoscope can remain on the shelf before use
Correct answer: The number of endoscope cycles an activated solution can support while remaining above MEC
Shelf life (or use life) refers to the maximum number of days or cycles an activated HLD solution can be used while maintaining concentration above the MEC.
CER Principles and Maintenance 2
Which parameter is most critical to monitor during automated endoscope reprocessing (AER) to ensure consistent disinfection?