Disclaimer: This post is for academic purposes only. Please read the original document if you intend to use them for clinical purposes.
This document summarises the ST91 white paper of ANSI/AAMI standard which serves as a guide for healthcare facilities regarding the reprocessing of flexible and semi-rigid endoscopes. As these devices are essential for diagnostic procedures but present significant decontamination challenges, strict adherence to standardized protocols is critical for patient safety and equipment longevity.
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1. Facility Design:
a) Workflow:
Proper facility layout is the foundation of effective reprocessing. The workflow should move linearly from a decontamination room to a clean room and then to a dedicated storage area.
- Workspace Considerations: Work surfaces, sinks, and counters should be height-adjustable or set at an average height to accommodate employees and specific tasks.
- Physical Separation: Decontamination areas must be physically separate from disinfection and sterilization areas. Pass-through windows at counter height are recommended for moving items between rooms.
- Personnel Safety: To alleviate physical stress from standing and bending, the use of anti-fatigue mats and back braces is encouraged.
b) HVAC and other environmental parameters:
Heating, ventilation, and air conditioning (HVAC) systems must conform to ANSI/ASHRAE/ASHE specifications:
- Decontamination Room: Must maintain negative pressure with at least 10 air exchanges per hour.
- Clean Room: Must maintain positive pressure with at least 10 air exchanges per hour.
- Monitoring: Facilities must establish systematic processes for monitoring HVAC performance and resolving variances.
c) Hygiene and Water Quality:
- Hand Hygiene: Hands-free sinks, soap dispensers, and towel dispensers should be located away from decontamination sinks. Technicians must wash hands before donning and after doffing PPE.
- Personal Grooming: Fingernails must be short (not exceeding the fingertip) and free of polish, acrylics, or extensions, which can chip and contaminate endoscope lumens.
- Water Quality: Using the correct water quality—monitored for pH, alkalinity, and hardness—is essential to reduce contamination risks and prolong device life.
- Eye Safety: Emergency eyewash units must be located within 10 seconds of chemical use/storage areas and maintained regularly.
2. Personnel requirements:
a) Training:
All personnel must complete formal training and competency verification before performing reprocessing tasks independently. Competencies should be updated annually to account for new devices, chemicals, and equipment.
b) Attire and Personal Protective Equipment (PPE):
Specific attire standards minimize the introduction of microorganisms and protect staff from hazardous exposures.
- General Attire: Staff must change into clean facility-provided scrubs daily. No jewelry or watches are permitted. All hair (including facial hair) must be covered.
- PPE Requirements: In decontamination areas, required PPE includes:
- Fluid-resistant face masks and protective goggles or full-face shields with drapes.
- Bouffant caps.
- Fluid-resistant gowns (tied in the back) with thumb loops to secure sleeves.
- Heavy-duty, waterproof, or lined sleeve gloves.
- Shoe covers or waterproof bootlegs.
- Heat Stress Management: Because fluid-resistant PPE traps body heat, cooling devices (cooling vests, bandanas, or skull caps) are recommended to prevent dehydration and fatigue.
3. Reprocessing Cycle:
a) Point-of-Use Treatment (Pre-cleaning):
Performed immediately after the procedure, before transport to decontamination:
- Wipe the insertion tube with a non-linting cloth/sponge and cleaning solution.
- Suction cleaning solution through channels.
- Flush air/water channels and other lumens according to the manufacturer’s Instructions for Use (IFU).
- Visually inspect for damage and attach fluid-resistant caps to electrical components.
b) Transport:
Endoscopes must be transported in a closed, “biohazard” labeled container large enough to prevent over-coiling (which can damage the device). If cleaning is delayed beyond 30 minutes, specialized packaging (like the Humipak) should be used to keep organic soils from drying.
c) Leak Testing:
Performed in the decontamination room before manual cleaning:
- Dry Leak Testing: Uses mechanical testers to check for pressure variances.
- Wet Leak Testing: The endoscope is submerged in water; a consistent stream of bubbles indicates damage.
d) Manual Cleaning:
- Immersion: The endoscope must be fully immersed in fresh cleaning solution for each use.
- Brushing: Use brushes of the specific length, width, and material required by the manufacturer’s IFU. All valves and channels must be brushed thoroughly.
- Rinsing and Purging: Rinse with potable water, purge channels with air to remove water, and dry the exterior with a low-linting cloth.
e) High-Level Disinfection (HLD) or Sterilization:
- HLD: Can be performed manually (soaking) or via an Automated Endoscope Reprocessor (AER). AERs are generally more efficient and reduce worker exposure to toxic chemicals.
- Sterilization: Methods include Ethylene Oxide (EO) or Hydrogen Peroxide (VHP/Ozone). Packaging must be compatible with the specific sterilization method (e.g., Tyvek for gas plasma).
- Rinsing: Following manual HLD, devices must be rinsed and then treated with 70-90% ethyl or isopropyl alcohol to facilitate drying.
4. Drying and Storage:
a) Importance of Drying:
Inadequate drying is a primary risk factor for patient-to-patient infection transmission:
- Microbial Growth: Bacteria can double every 20-30 minutes. An inadequately dried scope can host millions of bacteria within eight hours.
- Method: Channels must be dried with pressure-regulated medical-grade air or HEPA-filtered air.
b) Storage Standards:
- Positioning: Endoscopes should be hung vertically in a ventilated or HEPA-filtered drying cabinet with the distal tip hanging freely.
- Configuration: All valves and detachable parts must be removed during storage to allow for airflow.
- Labeling: Scopes should be tagged with the date of processing, the technician’s name, and “Hangtime” indicators.
- Risk Assessment: Facilities must conduct a multidisciplinary risk assessment to determine the “maximum safe storage time” (hangtime) before a scope requires re-processing.
5. Quality Control and Traceability:
a) Traceability and Record Keeping:
Facilities must maintain comprehensive records for every endoscope and reprocessing cycle such as Identification (i.e. Serial numbers of the endoscope and the AER used), Cycle Details (i.e. Date, time, cycle number, and lot number of chemicals), Personnel (i.e. Name of the technician who performed the processing), Patient Link (to cross-reference with procedure and physician for epidemiological tracking), Monitoring {i.e. results of Biological Indicators (BI) and Chemical Indicators (CI)}.
b) Visual Inspection and Verification:
Visual inspection must occur after cleaning but before HLD/sterilization.
- Enhanced Inspection: Use magnification and borescopes to inspect internal channels for pitting, stains, residual moisture, or debris that the unaided eye cannot detect.
- Cleaning Verification: Periodic testing for markers (analytes) such as protein, carbohydrate, hemoglobin, and ATP is required to benchmark cleaning effectiveness. These tests should be rapid, sensitive, and accurate.
c) Quality Assurance Program:
Facilities are mandated to establish a multidisciplinary safety program that includes:
- Standardized policies and procedures.
- Scheduled maintenance and removal of damaged equipment from service.
- Continuous training and annual competency assessments for all staff.
Citation: ST91 white paper: flexible and semi-rigid endoscope processing. Garden City (MI): HMark Systems; 2022. Available from: https://www.hmark.com/wp-content/uploads/2022/07/ST91-White-Paper-2022-03-10.pdf
