Inconsistent Ultrasound Transducer Disinfection Procedure Guidelines Confuse Processors

Ultrasound transducer (Adobe Stock)

Clinicians have ever-increasing choices to cleaning and disinfecting ultrasound transducers. Choosing the correct procedure is vital for patient safety, instrument longevity, and unnecessary costs. However, the requirements of which cleaning procedure should be used is often confusing and inconsistent. So, The American Institute of Ultrasound in Medicine (AIUM) introduced "Disinfection of Ultrasound Transducers Used for Percutaneous Procedures: The Intersocietal Position Statement" on February 19, 2021. This statement was created with input from members from the American College of Emergency Physicians, American Institute of Ultrasound in Medicine, Association for Professionals in Infection Control and Epidemiology, Association for Vascular Access, and the Society of Healthcare Epidemiology of America. Lately, however, the confusion continues to grow due to inconsistencies from various regulatory agencies.

To get more clarification, Infection Control Today^® (ICT^®) spoke with Oliver D. Kripfgans, PhD, FAIUM, is a research associate professor of radiology, biomedical engineering, and applied physics at the University of Michigan.

This is the second in a series of articles based on ICT^®’s exclusive interview with Krifgans on ultrasound transducers.

The first segment is here. The third is here. The fourth is here .

Infection Control Today^® (ICT^®): There are many different types of ultrasound procedures. What options do clinicians have for cleaning and disinfecting ultrasound equipment, and which options do you recommend?

Oliver D. Kripfgans, PhD, FAIUM: As the coordinator of AIUM’s taskforce on the cleaning and disinfection of ultrasound transducers used in percutaneous procedures, naturally, I recommend that practitioners follow the AIUM guidelines that apply to their procedures. The Intersocietal Position Statement that focuses on percutaneous procedures now has the support of 22 health professional organizations representing more than 800,000 members. It gives me goosebumps to realize how much uncertainty existed among so many individuals and organizations, and how appreciative they have been to have an authoritative clarification about proper disinfection practices for these procedures.

But as chair of AIUM’s technical standards committee, I also recommend that practitioners speak with the manufacturers of their ultrasound equipment because the work of this committee has revealed that practitioners sometimes improperly clean their equipment with agents that are not compatible with their ultrasound transducers. Incompatible disinfecting agents can damage transducers and other components, leading to equipment malfunctions.

AIUM’s guidelines are very specific about the steps involved in disinfecting transducers. The process begins with a simple cleaning—that is, removing any remnants of gel, tape, or other debris—until the transducer appears clean to the naked eye. Next, the transducer must be inspected for any crazing, cracks, or fogging that might have been caused by the use of disinfecting agents not approved by the manufacturer (damaged units should, of course, be removed from service). And, finally, the practitioner should use an approved process to disinfect the transducer in accord with its clinical application. Devices used in noncritical applications should receive low-level disinfection (LLD); devices used in semicritical applications should receive intermediate-level disinfection (ILD); and devices used in critical applications should receive high-level disinfection (HLD).

It is worth noting that the Intersocietal Position Statement does not use the term “intermediate-level disinfection.” We were advised to avoid that term because none of the relevant regulations currently provide an operational definition, leading to confusing interpretations in the guidelines issued by various associations. Instead, as a self-defining equivalent, we were encouraged to use the term “LLD effective against bloodborne pathogens.” This formulation makes a lot of sense and is roughly the same as the definitions used by Centers of Disease Control and Prevention, Food and Drug Administration, and Environmental Protection Agency. In effect, ILD is a method of processing that uses disinfectants proven to be effective against bloodborne pathogens.

After high-level disinfection, the next level of disinfection would be sterilization, which is almost never appropriate for ultrasound equipment. There have been some instances where novices have placed a transducer into an autoclave to perform sterilization, but afterward the transducer would not work anymore. To my knowledge, there is only 1 ultrasound unit—a transesophageal transducer—whose manufacturer has certified that it can be sterilized.

The level of disinfection should correspond to the criticality of the procedure, as outlined in the Spaulding Classification System. Ultrasound procedures that are performed over intact skin, or percutaneous procedures for the placement of vascular access lines, dictate the use of either LLD or ILD. ILD would be appropriate in the case of percutaneous procedures where the transducer might become contaminated with blood or other body fluids. Instances where aseptic technique is not followed, or where a transducer cover or barrier fails, would each call for the use of ILD.

By contrast, intraoperative and endocavitary (oral, transrectal, transvaginal) procedures call for the use of HLD. For my research on periodontal ultrasound, for instance, we have developed our own ultrasound probe. When disinfecting that probe before and after periodontal procedures, our residents are required to use HLD.

Practitioners who do not perform intraoperative or endocavitary procedures are not prohibited from using HLD, and some experts have suggested that doing so could provide an "extra margin" of protection against infection. But in the case of percutaneous procedures, there is no evidence to support the notion that HLD offers greater safety, and many experts have concluded that unnecessary use of HLD is generally not a prudent application of a facility’s resources.

Very few providers are so unconcerned about costs that they would not take action to reduce any unnecessary expenses. Procedure costs are important to providers, who would prefer to reduce those costs so that they can purchase the equipment needed to increase their ultrasound procedure throughput.

But in 2020, many practitioners were expressing their concern that requirements to perform HLD for transducers used in percutaneous procedures represented an imprudent and wasteful use of resources. Moreover, many people worried about facilities that lacked access to HLD technology, fearing that practitioners might continue performing their procedures—but without the benefit of ultrasound guidance.

ICT^®: That’s how the Intersocietal Position Statement came about; is that correct?

OK: Yes, it was these types of concerns that brought together the 5 associations that became the initial signatories of the position statement. All of these associations were very worried, because their members were receiving communications from either their local infection control boards or from the Joint Commission to the effect that practitioners should be using high-level disinfection even in the case of percutaneous procedures. Those instructions were controversial from the very beginning, as both individual practitioners and their professional associations agreed that the practices being required didn’t make any sense.

As the nation’s leading authority on medical applications of ultrasound, AIUM was brought on board to coordinate the efforts of a taskforce drawn from the signatory organizations. Our approach was to review all of the relevant peer-reviewed literature, assess the evidence in those publications, and develop recommendations for cleaning and disinfection that would not represent an undue burden on practitioners. We also looked at the recommendations of CDC and other authoritative bodies to see what they required for the cleaning and disinfection of other devices that are in the same situation as the ultrasound transducer.

Based on these reviews, in February 2021, the taskforce published the Intersocietal Position Statement in order to clarify what cleaning and disinfection procedures are actually needed in order to promote safe percutaneous procedures. And we considered the issue of safety in 2 ways: first, that the disinfection procedures should eliminate the risk of cross-contamination; and second, that the procedures should not inhibit the use of ultrasound for percutaneous procedures. Based on comments from some providers, there was great concern that if HLD were to be required, some practitioners might be left in the position of having to perform their procedures without ultrasound guidance. Such a change would have represented a significant reduction in patient safety, and greatly increased risk for patients.