6.3 Endoscope Reprocessing

Why Endoscopes Are the Highest-Risk Process

Flexible endoscopes — gastrointestinal (GI) scopes, colonoscopes, bronchoscopes, duodenoscopes — combine narrow, internal channels (lumens), delicate optics, and heat-sensitive materials that cannot be steam sterilized. They are semi-critical under Spaulding (contact mucous membranes), so the minimum acceptable processing is high-level disinfection (HLD), with sterilization preferred when the design tolerates a low-temperature method.

Real-world reprocessing failures — particularly with duodenoscope elevator mechanisms — have been directly linked to patient infection outbreaks, which is why this is a heavily tested, zero-shortcut topic.

The controlling consensus standard is ANSI/AAMI ST91:2021, Flexible and Semi-Rigid Endoscope Processing in Health Care Facilities. ST91 requires written procedures at the point of processing, documented staff competency, full IFU adherence, per-cycle documentation, and periodic microbial surveillance (culturing) of reprocessed scopes.

The Validated Reprocessing Sequence

1. Point-of-Use (Precleaning) Treatment — at the procedure site

Immediately after withdrawal: wipe the insertion tube, then flush/suction the channels with the IFU-specified enzymatic solution before bioburden dries. Transport in a closed, leak-proof, biohazard-labeled container to decontamination. Drying soil hardens into biofilm that HLD cannot penetrate.

2. Leak Test — before every cleaning cycle

Pressurize per IFU and submerge; air bubbles signal a breach in the sheath or a channel. A failed leak test = remove from service → tag as damaged → send for repair. A leaking scope must never be cleaned further or used — fluid intrusion destroys internal components and harbors contamination.

3. Manual Cleaning — the most critical step

Brush every accessible channel with the correctly sized brush; the brush tip should exit the distal end to confirm full-length passage. Flush channels with enzymatic detergent, clean the exterior, and clean all valves, buttons, and the biopsy port. Automated reprocessing cannot remove soil that manual cleaning missed.

4. Visual Inspection

Inspect the insertion tube for kinks/discoloration, the distal tip and lens for scratches, and confirm channels are patent and valves intact. Magnified or borescope inspection of channels is encouraged by ST91.

HLD/Sterilization Through Storage

5. High-Level Disinfection or Sterilization

Manual HLD: fully immerse, fill all channels with solution (no air pockets), hold the labeled contact time/temperature, and verify the minimum effective concentration (MEC) with test strips before each use. Automated endoscope reprocessor (AER): connect every channel adapter per IFU and confirm the cycle printout. AERs improve consistency but do not replace manual precleaning.

6. Rinse

Rinse exterior and all channels with critical water to remove chemical residue; inadequate rinsing causes chemical injury (mucosal burns) to the next patient.

7. Drying — mandatory

Flush channels with 70% isopropyl alcohol, then forced (filtered) air. Retained moisture promotes growth of waterborne organisms such as Pseudomonas. Drying is not optional.

8. Storage

Hang vertically in a ventilated (HEPA-filtered) drying/storage cabinet with valves and caps removed; do not coil tightly or lay flat. Honor the facility's maximum hang/storage time before reprocessing is required.

Common Errors and Consequences

Rigid and Semi-Rigid Endoscopes Versus Flexible

Not every scope is flexible. Rigid endoscopes — arthroscopes, laparoscopes, cystoscopes, and hysteroscopes — enter sterile tissue or body cavities and are therefore critical items that must be sterilized, not merely high-level disinfected. They have straight or simple channels but extremely delicate optical lens systems, so they are protected from impact, kept separated from heavier instruments, and disassembled per IFU before processing. Heat-tolerant rigid scopes can be steam sterilized; heat-sensitive optics require a low-temperature method.

Semi-rigid scopes (such as some ureteroscopes) bridge the two worlds and are explicitly covered by ST91 alongside flexible devices, which is why the standard's title reads "flexible and semi-rigid."

Why Documentation and Traceability Matter

Endoscopes are reused on many patients, so if an outbreak is suspected, the facility must answer two questions fast: which patients had this specific scope, and was each reprocessing cycle complete? ST91 therefore expects per-cycle documentation — scope identifier, the technician, the leak-test result, the HLD/sterilization parameters or AER cycle printout, and the date/time. Many departments tie each scope to the patient record so a single device can be traced through every encounter.

This traceability is the backbone of recall and outbreak investigation; without it, a reprocessing lapse cannot be contained to the patients actually at risk.

A Worked Scenario

A technician receives a duodenoscope after a procedure. Point-of-use wiping and channel flushing were done in the room, and it arrives in a closed transport bin. The leak test passes. During manual cleaning, the elevator mechanism brush does not pass cleanly and the technician feels grit. The correct action is to stop and reclean, not to advance to the AER — soil at the elevator is exactly the failure point implicated in duodenoscope-related infection outbreaks.

Only after the channel and elevator are visibly clean and the brush passes freely does the scope move to HLD or, preferably for duodenoscopes, sterilization or a sterilization-capable single-use design where adopted. Manual cleaning judgment, not the machine, protects the next patient.