By Mary Ann Drosnock, DHSc, CIC, CFER, RM(NRCM), FAPIC, AAMIF
Head of Clinical Affairs, Healthmark Industries, a Getinge company
Contaminated endoscopes remain one of the most significant and persistent causes of healthcare-associated infections (HAIs). Despite years of research, detailed guidelines, and ongoing technological innovation, outbreaks continue to occur across the globe. These incidents are complex, often involving delayed symptom onset, underreporting, and the reuse of instruments that are difficult to fully decontaminate. As a result, endoscope reprocessing continues to be one of the most scrutinized and evolving areas in infection prevention.
While several references in this article relate to U.S. standards and regulatory updates, the underlying principles and challenges of endoscope reprocessing apply globally across healthcare systems.
Updated guidelines and standards
In the United States, the Association for the Advancement of Medical Instrumentation (ANSI/AAMI) ST91:2021 standard remains the foundational reference for the reprocessing of flexible and semi-rigid endoscopes in healthcare facilities. It defines best practices from precleaning through storage and reuse and applies to all clinical settings. ST91 emphasizes unidirectional workflow, environmental separation between dirty and clean areas, leak testing, cleaning monitoring, and the use of lighted magnification and borescopes for inspection (ANSI/AAMI, 2021).
In Europe, healthcare facilities do not follow a single binding standard equivalent to ANSI/AAMI ST91. Instead, endoscope reprocessing practices are based on a combination of national regulations, government technical memoranda, and professional society guidelines such as those published by the European Society of Gastrointestinal Endoscopy (ESGE) and the European Society of Gastroenterology and Endoscopy Nurses and Associates (ESGENA), which are used to develop local protocols within healthcare facilities.
New revisions of the U.S. guidelines and standards also reaffirm the importance of drying. Endoscopes must be thoroughly dried internally and externally, either via instrument quality or HEPA filtered compressed air (typically for 10 minutes) or within drying cabinets that provide forced air through the endoscope channels prior to storage and reuse. ST91 discourages manual high-level disinfection (HLD) except in emergency situations and supports transitioning sterilization-compatible scopes to sterilization whenever possible.
These evidence-based updates align with The Association of periOperative Registered Nurses (AORN) Guidelines for Perioperative Practice (2023) and Society of Gastroenterology Nurses and Associates (SGNA) infection prevention standards (2023), which collectively advocate standardized handling, staff competency, and water quality testing to ensure effective reprocessing.
Regulatory updates and recalls
The U.S. Food and Drug Administration (FDA) continues to monitor and issue alerts regarding endoscope-related contamination and device malfunctions. Between 2024 and 2025, multiple Class I recalls were issued for flexible endoscope accessories, including the MAJ-891 forceps/irrigation plug and single-use guide sheath kits, due to contamination retention and mechanical failure risks (FDA, 2025a, 2025b). In June 2025, the FDA imposed import restrictions on certain Olympus devices manufactured in Japan, including ureterorenoscopes, bronchoscopes, laparoscopes, and automated endoscope reprocessors (FDA, 2025c).
Such actions reinforce that patient safety depends not only on device design but also on adherence to validated Manufacturer Instructions for Use (MIFU) – specifically, initiating manual cleaning within one-hour post-procedure (Day, 2021) and avoiding extended detergent soaks where possible. Adherence to manufacturer instructions, validated workflows, and prompt corrective action are foundational expectations across regulatory and accreditation frameworks, even where the specific mechanisms differ.
Persistent infection risks and underreporting
Research continues to show that endoscope-related infections outnumber those linked to any other reusable medical device (Kenters et al., 2015; Rutala & Weber, 2019). A 2024 genomic sequencing investigation found a mean incubation period of 86 days (range, 1–320 days) from procedure to positive index culture in patients infected with NDM-producing organisms, illustrating how long detection can lag exposure and complicating outbreak tracing (Suleyman et al., 2024).
Additional studies have documented contamination in endoscopes used across gastrointestinal, urological, and pulmonary specialties – even when reprocessing records indicated full compliance. Common contributors include damaged channels, residual moisture, and insufficient inspection practices. Routine use of borescopes and magnifiers has been shown to detect channel damage, residual debris, and moisture invisible to the naked eye (Ofstead et al., 2023).
Simethicone: A growing concern
Simethicone, a silicone-based anti-foaming agent used during endoscopy to improve visualization, continues to be a hidden contamination risk. The compound’s hydrophobic, non-water-soluble properties make it difficult to remove, and residues have been detected in channels even after repeated cleaning and disinfection (Ofstead et al., 2019; Barakat et al., 2019).
Studies by Ofstead and associates determined that simethicone may harbor residue and moisture that could compromise disinfection (Ofstead et al., 2016; Ofstead et al., 2019). Current recommendations from the American Society for Gastrointestinal Endoscopy (ASGE) and SGNA advise limiting simethicone to the lowest effective concentration and restricting administration to the biopsy port only, never through the water jet (Day et al., 2021).
Additionally, manufacturers such as Olympus, Pentax®, and Fujifilm® have released statements cautioning against simethicone use in water channels. New water-based, soluble alternatives offer similar visualization benefits without the persistence of residues or additives like sugars and thickeners (Mallard, 2023).
Best practices: Inspection, drying, and competency
Evidence from Ofstead et al. (2024) shows that routine borescope inspection of every endoscope after manual cleaning was associated with significant reductions in repair frequency and cost over a three-year period. Each endoscope should be visually inspected under magnification, with routine use of cleaning monitoring tests such as adenosine triphosphate (ATP), protein, and hemoglobin (AAMI, 2021). Periodic borescope examination is also strongly recommended to detect internal channel damage, residual debris, or retained fluid that surface inspection and cleaning markers will miss.
The drying phase remains one of the most critical yet frequently underperformed steps. Moisture left inside channels support microbial proliferation and biofilm development, and real-world data show the problem is widespread. In a multisite study, retained moisture was detected in 49% of patient-ready endoscopes, and microbial growth was found in 71%, where retained fluid was associated with higher ATP levels (Ofstead et al., 2018).
These findings underscore why endoscopes must be thoroughly dried before storage – whether by forced air or by drying cabinets that deliver filtered air directly through the channels – and why drying monitoring should be built into routine practice. In addition, staff competency and continuing education play an essential role. Training must go beyond procedural steps to include a) rationale and risk awareness, b) empowering technicians to recognize damage, c) improper loading, or d) deviations from the MIFU. Continuous competency validation and participation in structured educational and credentialing programs help reinforce a culture of quality assurance.
The cost of noncompliance
Beyond infection risks, reprocessing failures impose substantial financial and operational burdens. Operating Room (OR) time costs approximately $36–$37 per minute in direct institutional costs (Childers & Maggard-Gibbons, 2018), and sterile processing failures have been estimated to generate between $6.75 million and $9.42 million in lost chargeable OR minutes annually at a single academic campus (Nichol et al., 2024). A U.K. study across three hospital sites within the National Health Service (NHS) found that sterile instrument wrapping defects led to case cancellations, delays, and repackaging costs totaling approximately £145,000 (approximately $192,000 US dollars) over a seven-month period (Anazor et al., 2022). Device damage resulting from improper handling or incomplete drying can lead to costly repairs or premature replacements.
More importantly, patient injury or infection from an inadequately reprocessed endoscope carries reputational and regulatory repercussions, potentially resulting in citations, litigation, and accreditation review.
Looking ahead: The next frontier in endoscope reprocessing
Ongoing work on ISO 25224 (Sterilization of Health Care Products – Sampling and Culturing for Reusable, Thermolabile Flexible Endoscopes), currently in development, is expected to provide further clarity on microbial surveillance and culturing methods. This international collaboration represents an important step toward global alignment on endoscope safety practices, specifically how to sample an endoscope for routine bacterial surveillance.
In addition, the anticipated revision of ANSI/AAMI ST79 on steam sterilization will further bridge the gap between reusable device processing and endoscope reprocessing standards. Until then, the current standard is ANSI/AAMI ST79:2017 with amendments A1–A4 from 2020, which was reaffirmed in 2022.
Conclusion
Endoscope reprocessing remains one of the most demanding tasks in infection prevention. The margin for error is so small that a single retained channel of moisture or an unnoticed scratch can carry an organism to the next patient. The persistence of device-related infections (despite decades of guidance) shows that reprocessing quality depends less on any single technology than on whether facilities verify their work.
Concretely, that means a) inspecting every endoscope under magnification, b) using borescopes to check internal channels, c) periodically check dryness prior to storage using a borescope or drying indicator, d) running cleaning process protein indicator rather than assuming a clean result, e) keeping staff competency current, and f) report when necessary. Facilities that incorporate these checks into routine practice and monitor the outcomes are the ones that catch issues before a patient does.
References
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