Flexible and semi-rigid endoscopes are reused every day in hospitals. Guidelines for cleaning, disinfecting and reprocessing endoscopes vary by manufacturer. Hospitals and oversight committees also offer reprocessing guidelines.
But what happens after reprocessing?
After being disinfected, endoscopes must be stored and dried properly to prevent recontamination because storing them wet fosters microbial growth—even if stored for brief periods.
While endoscope reprocessing guidelines provide a wealth of detail about cleaning and disinfection, less emphasis is placed on post-disinfection procedures. Most published guidelines suggest freshly-disinfected endoscopes be rinsed, dried and hung in storage. There are practical considerations, however, for each step.
The Society of Gastroenterology Nurses and Associates regularly outlines common steps in drying and storing endoscopes, based on multisociety guidelines. The Association for the Advancement of Medical Instrumentation, a nonprofit, also publishes processing guides that touch on endoscope drying and storage procedures.
At the federal level, the guidance is more general. “After reprocessing is complete, store endoscopes and accessories in a manner that prevents recontamination, protects the equipment from damage, and promotes drying,” writes the Healthcare Infection Control Practices Advisory Committee, a federal advisory committee to the Centers for Disease Control and the secretary of the Department of Health and Human Services.
The Joint Commission, which accredits and certifies nearly 21,000 health care organizations and programs in the U.S., has responded to concerns about limited guidance through a series of webinars and industry collaborations to validate instructions and understand practical challenges. Still, the Joint Commission indicates procedures for endoscopes post-reprocessing “will depend on the evidence-based guideline that you have chosen within your organization” and that hospital staff “follow your organizational policy and procedure.”
Despite all the information available through professional societies and the medical literature, developing endoscope drying protocols can be challenging for hospitals. Guideline variations only add to the challenge.
Hospitals must evaluate air pressure relationships, exchange rates and filtration efficiencies—and integrate these evaluations with endoscope usage rates, clinic workflow and budget constraints.
After cleaning and high-level disinfection, endoscopes must be rinsed to protect subsequent patients from chemical exposure. Rinse water presents a contamination risk as it can quickly become contaminated by pathogens persisting on the endoscope. One study tested 418 rinse water samples across 20 endoscopy units. While many samples were sterile, 60 percent contained bacteria.
The researchers’ conclusion? It may be unrealistic for hospitals to keep endoscope rinse water entirely bacteria-free.
For maximum infection prevention, endoscopes should be dried after every reprocessing cycle is completed, both between patient procedures and before storage. The Centers for Medicare and Medicaid Services recommend flushing all channels with 70 percent to 90 percent ethyl or isopropyl alcohol and then drying by forced, filtered air (including the elevator mechanism).
Ethanol is not recommended for endoscope drying due to its fixative properties.
Endoscopes that remain wet pose a serious contamination risk. Many hospital outbreaks have been associated with improper drying of flexible endoscopes, including those caused by P. aeruginosa, S. marcescens, M. tuberculosis, and M. chelonae. In a three-site study of 45 “patient-ready” endoscopes, nearly half (49 percent) still had fluid in them.
Pathogens may be more likely to multiply in this moist, humid environment. Bacteria can also form biofilms if moisture remains for long periods. If left wet, even endoscopes that pass initial contamination tests may, over time, harbor a bacterial burden that renders them unusable.
Detaching removable parts—including caps and valves—allows for more complete drying, facilitating air flow into endoscope channels that are at the highest biofilm risk. For endoscopes without detachable parts, valves should be open during drying. Special consideration should be given to endoscope tip protectors, which can trap moisture and cause microbial growth.
Endoscopes should hang vertically to ensure complete drying. Some associations include provisions for horizontal drying, if the endoscope is in a cabinet specifically designed for channel drying. Endoscope manufacturers will also say whether scopes should be hung vertically or horizontally to dry—although The Joint Commission has consistently recommended vertical drying.
Drying endoscopes should hang freely, with no risk of physical damage from bumping into other scopes or surfaces. This also prevents moisture buildup at contact points.
Once flexible endoscopes are disinfected and dried in accordance with manufacturer, agency and organizational guidelines, they are ready for reuse. There are many approaches to storing endoscopes at the ready.
Drying cabinets that circulate filtered air can also double as storage cabinets. These include cabinets that store scopes horizontally and vertically. When retrieving endoscopes from storage, staff should be sure the scope is dry—endoscopes that are not dry must be reprocessed before use, according to the Society of Gastroenterology Nurses and Associates Inc.
There are many flexible endoscope storage units available on the market, ranging from simple racks that can be mounted on a vertical surface to locked, barcode-activated cabinets that can track inventories. The Joint Commission recommends endoscope storage units be in a central, risk-assessed location with minimal foot traffic. This helps hospitals maintain an accurate, documented endoscope inventory.
This location should not be in the procedure room, according to the Association of periOperative Registered Nurses (AORN).
The most controversial issue in endoscope storage is “hang time” or shelf life—how long an endoscope can be stored (properly) before reprocessing is needed. There is no conclusive evidence on the length of time endoscopes can be safely stored before requiring re-disinfection and before they pose a contamination risk—a persistent industry lament.
Some research indicates endoscopes stored for seven to 14 days are at negligible risk of contamination beyond common skin organisms on the outside of the scope. An analysis of 10 studies on the topic found endoscopes can be stored for seven days before requiring reprocessing, but that ongoing surveillance cultures are necessary. Endoscopes that are used infrequently and sit for longer periods may require scheduled, intermittent reprocessing.
Similarly, facilities where scopes are used in patients at high risk of infection, or in procedures with entry into sterile body cavities, may also benefit from more stringent storage limits.
Agency hang-time recommendations vary. Some agencies used to set upper storage limits but now say there’s insufficient evidence to do so. In 2012, for example, AORN recommended a five-day reprocessing. In 2016, it described a safe storage range of 48 hours to 56 days. A task force of 11 endorsing organizations, including The Joint Commission, now considers the “interval of storage after which endoscopes should be reprocessed before use” an unresolved issue.
Instead of relying on agency consensus for storage limits, hospitals are encouraged to develop microbial surveillance strategies to set their own (evidence-based) limits. This must be balanced with personnel time, materials costs and an inherent risk of damage to flexible endoscopes due to more frequent reprocessing. Damaged scopes may be more likely to harbor contamination.
It’s difficult to standardize other, though related, elements of endoscope storage. Storage cabinets should be cleaned, but the frequency of cleaning depends on how often it is opened. Cabinet cleaning also risks contaminating stored endoscopes, or having to reprocess entire batches. Hospitals should compare storage cabinet manufacturer recommendations to their own needs, and perform a risk assessment to determine cleaning frequency, according to The Joint Commission.
Documenting flexible endoscope drying and storage periods can help improve staff accountability and support audits. The Centers for Disease Control and Prevention provides a toolkit of sample documents to incorporate into an endoscope reprocessing program. More information about endoscope documentation and tracking is also available on the Bedside Bronchoscopy site.
The Joint Commission is quick to remind hospitals: “Do not take proper endoscope reprocessing lightly. The long-term effects of poor processes and an unsafe environment are severe.” This warning extends post-reprocessing and must also be considered for endoscope drying and storage.