Endoscope Reprocessing: The Process and Where It Fails

Flexible endoscopes are reusable, heat-sensitive devices that contact mucous membranes, which makes them semicritical devices under the Spaulding classification — meaning high-level disinfection (HLD) is the minimum acceptable reprocessing level, with sterilization an option where the device and facility support it. What makes endoscope reprocessing unusually high-liability compared with other semicritical devices is the instrument itself: long, narrow internal channels, complex mechanical components (most notably the elevator mechanism on duodenoscopes), and a multi-step manual process performed under time and volume pressure between procedures. Outbreaks traced to inadequately reprocessed endoscopes are among the most consistently documented reprocessing-failure events in healthcare epidemiology, which is why endoscope reprocessing has its own dedicated AAMI standard rather than being left to the general Spaulding/HLD framework alone.

The Standard Reprocessing Sequence

While exact steps and timing are set by the device manufacturer’s instructions for use (IFU) and by the specific automated endoscope reprocessor (AER), if one is used, the sequence recognized across CDC guidance, the multi-society guideline (jointly issued by gastroenterology and GI-nursing professional societies together with AAMI), and ANSI/AAMI ST91 follows the same general structure:

1. Point-of-use pretreatment. Immediately after the procedure, while still in the procedure room, the endoscope is wiped externally and its channels flushed with an enzymatic detergent or manufacturer-specified pretreatment solution. This step exists specifically to prevent organic material from drying inside the channels before cleaning can begin — delay here materially increases the difficulty of adequate cleaning downstream.
2. Leak testing. The scope is pressure- or manually leak-tested before immersion, to confirm the internal channels and external sheath are intact. A scope that fails leak testing must not proceed through wet reprocessing or use, since fluid intrusion into non-waterproof internal components causes damage and can compromise future disinfection.
3. Manual cleaning. Thorough brushing of all accessible channels and ports, combined with flushing, using an enzymatic cleaning solution at the manufacturer-specified dilution and contact time. This is widely regarded as the single most consequential step in the sequence: no downstream disinfection or sterilization step can compensate for organic soil or biofilm that manual cleaning failed to remove.
4. Visual inspection, increasingly supplemented in modern programs by borescope (small-bore camera) inspection of internal channels, since debris and channel damage are not reliably visible from the exterior or channel openings alone.
5. High-level disinfection or sterilization, typically performed in a validated automated endoscope reprocessor (AER) using an FDA-cleared high-level disinfectant, per that product’s cleared label and the AER’s validation for the specific scope model.
6. Rinsing with the water quality specified by the AER and disinfectant label (often requiring filtered or otherwise treated water to avoid recontaminating a just-disinfected scope).
7. Drying. Forced-air channel drying, often followed by an alcohol flush to promote evaporation of residual moisture, is now treated as a mandatory, distinct step rather than an afterthought — residual moisture in a channel is one of the most consistently cited enablers of microbial growth between uses.
8. Storage. Scopes are hung vertically in a ventilated, closed storage cabinet (increasingly a drying cabinet that continues forced-air channel drying during storage), with a facility-defined maximum hang time before reprocessing must be repeated even if the scope was not used.

Every step in this sequence is also a documentation point: reprocessing programs are expected to record who performed each step, when, and with which specific scope (by serial number) and which specific reprocessing cycle/lot, so that if a device or product failure is later identified, every patient exposed to that specific scope in that time window can be traced. This instrument-level, patient-linked traceability is now a standard expectation in endoscope reprocessing programs, not an optional enhancement.

The Standard Behind the Process: ANSI/AAMI ST91

ANSI/AAMI ST91, Flexible and semi-rigid endoscope processing in health care facilities, is the dedicated consensus standard covering this exact device category, distinct from ANSI/AAMI ST79, which governs steam sterilization of devices generally. ST91 was developed specifically because flexible endoscopes’ combination of heat sensitivity, channel complexity, and mechanical components (elevator wires, working channels, air/water channels) made the general Spaulding/HLD framework insufficient as a stand-alone operational reference. It works alongside — not instead of — the device manufacturer’s own IFU, which remains the enforceable, device-specific instruction for a given scope model.

The Duodenoscope Elevator Channel: A Known, Documented High-Risk Point

Duodenoscopes (used in ERCP procedures) carry an elevator mechanism at the tip that allows accessories to be angled — a moving mechanical component with a narrow recess that is difficult to fully access with a brush and has been specifically implicated in documented healthcare-associated outbreaks, including transmission of carbapenem-resistant organisms, reported through the 2010s. In response, FDA issued safety communications and manufacturer post-market surveillance orders addressing duodenoscope reprocessing risk, and manufacturers subsequently introduced design changes — including disposable-elevator-cap components and fully single-use duodenoscope models — intended to reduce or eliminate the elevator-channel reprocessing risk entirely. Facilities using reusable duodenoscopes with a fixed (non-disposable) elevator channel should confirm their reprocessing protocol reflects the current FDA guidance and manufacturer IFU for that specific model, since this is an area where recommended practice has continued to evolve.

Common Failure Points

• Delayed point-of-use pretreatment — allowing organic material to dry in a channel before cleaning begins, which manual cleaning downstream may not fully reverse.
• Incomplete manual cleaning — a rushed brushing step, an unbrushed port, or a cleaning solution used past its labeled reuse/dilution life.
• Biofilm formation in channels from repeated incomplete cleaning cycles, which is substantially harder to remove once established than fresh organic soil and can shield organisms from the disinfection step entirely.
• Inadequate drying before storage — the failure point most directly linked to between-use microbial growth in a correctly-disinfected scope.
• Skipping or superficially performing leak testing, missing internal damage that both compromises disinfection and risks further damaging the scope.
• Storage beyond the defined hang time without re-reprocessing, or storage in a non-ventilated cabinet that traps residual moisture.
• Understaffing and throughput pressure in the reprocessing area relative to procedure volume — a program-level, not individual-technician, failure point that facility leadership and value-analysis committees are responsible for resourcing correctly.

How This Differs From FDA Single-Use Device Reprocessing

Routine endoscope reprocessing — cleaning and disinfecting a scope the manufacturer designed and labeled for repeated use — is standard sterile-processing/endoscopy-unit work governed by the manufacturer’s IFU and ANSI/AAMI ST91, not by FDA’s separate regulatory track for reprocessing devices labeled “single-use.” That second, distinct category is covered in our guide to medical device reprocessing regulation and procurement. The two are easy to conflate in policy documents but are governed differently, and endoscope reprocessing as covered on this page is the former.

Frequently Asked Questions

Is high-level disinfection enough for endoscopes, or do they need to be sterilized?

High-level disinfection is the Spaulding-classification minimum for semicritical devices, including most flexible endoscopes, and is the standard practice for scopes that cannot tolerate sterilization. Where a facility has access to low-temperature sterilization compatible with a given scope, sterilization is an acceptable alternative, but it is not required by the classification itself.

What causes most endoscope reprocessing failures?

Incomplete manual cleaning and inadequate drying are the two most consistently cited failure points in reprocessing-related outbreak investigations and professional-society guidance — both are steps that no later stage of the process can fully compensate for.

How long can a reprocessed endoscope sit in storage before it needs to be reprocessed again?

Facilities set a maximum hang/storage time in policy, based on the scope manufacturer’s IFU and applicable AAMI guidance (ANSI/AAMI ST91); it is not a single figure that applies uniformly across every device and storage system, particularly given the more recent shift toward drying cabinets that extend safe storage relative to older passive storage.

What is the elevator channel and why is it a specific concern for duodenoscopes?

It is the moving mechanical mechanism at the tip of a duodenoscope used to angle accessories during ERCP. Its design creates a narrow recess that is difficult to fully clean, and it has been specifically linked to documented outbreaks — which is why FDA and manufacturers introduced disposable-elevator and fully single-use duodenoscope design changes.

Who is responsible for endoscope reprocessing oversight in a hospital?

Typically a shared responsibility between endoscopy unit/sterile processing leadership (who own the day-to-day process) and the facility’s infection preventionist (who owns surveillance, policy review, and outbreak investigation if a reprocessing-linked infection is identified).

See also our guide to the underlying Spaulding classification and high-level disinfection, Sterile Processing Department (CSSD) Equipment Purchasing, and the patient safety and infection prevention pillar.