Mary Ann Drosnock: An Exciting Overhaul for ANSI/AAMI ST91

By now, most facilities are familiar with the 2015 national standard, ST91, from AAMI, entitled Flexible and semi-rigid endoscope processing in health care facilities. But did you know that the document was recently revised? The new 2021 version represents a complete overhaul of the standard.

Meticulous attention to all steps in processing flexible endoscopes and accessories is critical to ensure that they are rendered safe for subsequent patient use. ST91:2021 focuses on instituting quality measures to improve patient safety related to endoscope processing. There are numerous changes in both recommendations and requirements found within the document.

There are many critical areas of focus in the new ST91, including an emphasis on training, competency, and certification, as well as considerations for the design of the processing area, environmental, HVAC, and water quality monitoring. There are expanded sections on contaminated transportation of scopes, updates to precleaning (now termed point-of-use treatment), and a focus on leak testing and associated equipment testing.

One totally new area found in the standard is the identification of high-risk scopes. High-risk scopes, such as bronchoscopes and duodenoscopes, will require additional processing steps like cleaning verification.

Both external inspection using lighted magnification and internal inspection using a borescope is highlighted as well as cleaning verification testing. Notably, there is a recommendation against performing manual disinfection (e.g., soaking in a basin of disinfectant) and instead, we recommend processing all endoscopes in an automated endoscope processor (AER). Additionally, sterilization is reaffirmed to be the preferred method of processing for all endoscopes—with the caveat that the industry is “not quite there” for some types of scopes. Drying is another expanded topic within the new standard.

Although there is no timeline established through ST91 for a facility to implement these changes, I recommend that each facility obtains a copy of the new standard and begins a thorough review of it as soon as possible. Put together a multidisciplinary team to review the guidance, and create a crosswalk of noncompliance topics based on the current practices at the facility. Then, I’d recommend that each facility create an implementation strategy with due dates assigned to each of them. Prioritize issues based on their criticality, availability, budget, low-hanging fruit, etc. Begin the implementation of the changes and hold staff accountable for the project timelines.

Based on the new standard, it is clear that endoscope processing per the standard will cause cycles to take longer and have a higher cost. But that is offset by the increase in quality and patient safety and a decrease in the potential for adverse events and infections. I am very excited to see this document through to its publication, and I am so pleased that I was a part of it!

The new standard is available at

Mary Ann Drosnock is director of clinical affairs at Healthmark Industries in Fraser, MI, and former co-chair of AAMI ST/WG 84, the working group responsible for endoscope processing. This working group is currently revising ST91, the national standard for processing flexible and semi-rigid endoscopes in Healthcare facilities, and is newly creating TIR99 – Dilators, transesophageal, and ultrasound probes processing in Healthcare facilities.

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