Should the CDC Change its Guidance on Ultrasound Transducer Disinfection?

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Because choosing the correct procedure to clean ultrasound transducers is vital for patient safety, instrument longevity, and avoiding unnecessary costs, it is dangerous that the requirements of which cleaning procedure should be used is often confusing and inconsistent. When 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 tried to eliminate the confusion, but it did not…yet. Lately, however, the confusion continues to grow due to inconsistencies from various regulatory agencies.

In this third installment of Infection Control Today^®'s interview with Oliver D. Kripfgans, PhD, FAIUM, a research associate professor of radiology, biomedical engineering, and applied physics at the University of Michigan, Krifgans discusses the real-life consequences of requiring high-level disinfection (HLD) for the ultrasound transducers.

The first installment of the interview is here. The second installment is here. The fourth installment is here. 

Infection Control Today^®: In addition to the costs involved in performing high-level disinfection, there’s also significant time required. Does the wait time for a transducer to be processed contribute to practitioners performing their procedures without ultrasound guidance?

Oliver D. Kripfgans, PhD, FAIUM: This is exactly what providers told us. Especially in emergency care settings, time is not on the side of the practitioner. When a patient needs ultrasound-guided treatment, there is no time to wait for disinfecting equipment to warm up and then perform a high-level disinfection (HLD) cycle that may take more than a few minutes. So if physicians are forced to use HLD, there is a good chance that some will decide to just skip the use of ultrasound all together.

By contrast, the Intersocietal Position Statement supports the view that low-level disinfection (LLD) with proper responsiveness against bloodborne pathogens is sufficient for disinfecting transducers used for percutaneous procedures. Using this approach avoids the financial burden associated with HLD, and also provides for a turnaround time that is very quick. Practitioners are used to using transducer covers and barriers, and they are also used to wiping down their equipment with disinfecting wipes. These are standard procedures used in virtually all health care settings, and they do not impede the use of ultrasound.

ICT^®: The position statement calls for the use of “LLD effective against bloodborne pathogens.” How is this viewed by the peer-reviewed literature?

OK: Guidelines from regulatory agencies such as the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) frequently call for the use of intermediate-level disinfection (ILD), but they are typically ambiguous about what constitutes an ILD process, or when it should be applied. The term “LLD effective against bloodborne pathogens” is a practical and self-defining equivalent to “ILD,” and specifies the level of disinfection that is expected to be achieved.

In the corrigendum issued for the study involving 800 patients who underwent a peripheral IV catheter insertion, the researchers indicate that their equipment was disinfected using “readily available germicidal disinfection wipes” that are effective against mycobacteria and thus act as an ILD.

Beyond that single study, the peer-reviewed literature is mostly silent on the subject of transducer disinfection for percutaneous procedures. It would be helpful to have more studies in the literature about the performance of ultrasound-guided line placements, with cohorts that would enable a comparison of outcomes from using LLD, ILD, and HLD. We would expect a comparison between ILD and HLD to demonstrate that there is no difference in the risk to patients.

It is important for associations that are preparing guidance documents to assess the peer-reviewed literature very carefully. Right now, much of the literature about ultrasound-associated infections fails to distinguish among such potentially causative factors as contaminated coupling gel, failure to use a transducer cover or barrier, or the level of disinfection applied to the transducer. These are fundamentally very different factors, and it is dangerous to create guidance documents without having a clear understanding of the cause-and-effect relationships among them. More practically, it is not within the practitioner’s control whether a gel is contaminated, but it is within the practitioner’s control to use an appropriate cover or barrier, or to comply with required levels of disinfection.

If there is confusion about what level of disinfection should be used, I always tell people that the level of a procedure’s sterility should dictate the corresponding level of disinfection. A procedure that is commonly performed using sterile gloves should probably require the use of HLD. But if the procedure can be performed using regular exam gloves, it probably requires only LLD or ILD.

ICT^®: You mentioned that CDC’s guidance documents do not define ILD or describe its application for percutaneous procedures. Is there a reason why the agency hasn’t endorsed the position statement—especially when it has the support of health professional organizations representing over 870,000 members?

OK: CDC’s guidance documents predate the Intersocietal Position Statement by many years. Moreover, the rapid expansion in the use of point-of-care ultrasound procedures is a somewhat recent phenomenon. Consequently, the need for critical thinking about the proper procedures for cleaning and disinfection of point-of-care ultrasound equipment is relatively young when compared to CDC’s broader guidelines for ultrasound procedures.

As background for writing the position statement, members of the taskforce spoke with the lead authors of CDC’s guidelines pertaining to cleaning and disinfection. They fully understood the problem that is addressed by the position statement, and they indicated that they would take this into account the next time they revise CDC’s guidance documents. However, we don’t know when the agency will address that task, and about all we can do is encourage the agency to do so. We do hope that having so many associations and their members expressing their need for—and support of—the position statement will make it a little easier to convince CDC to revise its guidance documents sooner rather than later.

But it takes time to build support for such an effort, and it also takes time for regulatory agencies to move such requests to the top of their to-do lists. It’s fair to say that this is an area in considerable flux, but we shouldn’t expect a resolution to all the issues overnight.