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Factors to consider for point of care reprocessing of ultrasound probes

Ultrasound is a versatile medical technology that has become ubiquitous throughout healthcare. The use of diagnostic ultrasound in the United Kingdom has increased steadily in recent years with the number of procedures in England rising from 7.7m in 2013 to 10.2m in 2019.1 Reprocessing of ultrasound probes is also evolving, as facilities move away from manual processes towards automated systems that require less hands-on time while still being safe and effective for point of care use. For all point of care reprocessing, there are factors that facilities and healthcare staff should consider to maximise the safety and efficiency of disinfection workflows.

The emergence of point of care ultrasound

As ultrasound devices become smaller and more portable, the role of ultrasound as a diagnostic tool at point of care is becoming more established. Point of care ultrasound (PoCUS) is an indispensable tool for triage and management in acute care environments like intensive care units and emergency departments.2,3 Other specialties including obstetrics and gynaecology, urology and general practice are also benefitting from PoCUS.4-6

Alongside this increase in the use of PoCUS comes a greater focus on the importance of standardisation of medical device reprocessing workflows. For ultrasound probes, this means applying the Spaulding classification to each ultrasound probe before use on a patient (Figure 1).

Figure 1. The Spaulding classification divides infection transmission risk based on the type of patient tissue the device will contact during use, which determines the level of disinfection. If sterilisation of critical devices is not possible, such as with ultrasound probes, they can minimally undergo HLD and be used with a sterile sheath.7,8

Applying Spaulding at point of care

The Spaulding classification system is a rational approach to disinfection and sterilisation of medical devices that contact the patient. This universally accepted classification scheme has been retained, refined and successfully implemented in clinical settings for over 50 years. It also forms the basis of national standards and guidelines around medical device reprocessing.7-12

Spaulding divides infection transmission risk based on the type of patient tissue the device will contact during use. As ultrasound machinery becomes more portable and PoCUS becomes more widespread, consistently applying Spaulding to each use of a probe remains essential. Ultrasound probes used at point of care are often shared between rooms, departments or operators, and used in a range of procedures requiring different levels of disinfection. For example, the same probe might be used as a non-critical device in a diagnostic scan on intact skin, then later as a critical device during an invasive procedure. In the first scenario, the probe requires only low-level disinfection. But in the second procedure, the probe is classed as critical and requires high-level disinfection and the use of a sterile sheath at a minimum.7,8

Infection risk from ultrasound 

Ultrasound probes contact a range of hazards during use, putting them at high risk of becoming contaminated with pathogens. A study in emergency rooms and intensive care units found that over 50% of ultrasound probes had blood contamination.13 In other settings, over 90% of transvaginal ultrasound probes have been found to be contaminated with bacteria after use.14,15Even after low-level disinfection with wipes and sprays, probes can be contaminated with viruses and bacteria, including pathogens that can cause sexually transmitted infections like human papillomavirus (HPV) and Chlamydia trachomatis.16,17

A landmark epidemiological study by the Scottish health authority reported an increased risk of infection in the 30 days following an endocavitary ultrasound scan, where low-level disinfection was the practiced standard of care.18 The study followed almost 1 million patient journeys retrospectively through linked national patient datasets between 2010 and 2016. Following the study, the Scottish government mandated high-level disinfection for semi-critical probes, including endocavitary probes.10

This infection risk is not confined to endocavitary probes. Surface probes are unique in that they are used in medical procedures that span all three categories under the Spaulding classification system (critical, semi-critical and non-critical) depending on the type of tissue that the probe contacts during use. Consistently applying the Spaulding classification to each use of a surface probe is essential to prevent outbreaks.  In 2021, an intraoperative probe was the source of an outbreak in patients undergoing hepatic surgeries.19 Inadequate reprocessing of the probe was identified as one of the contributing factors. Another study found that ultrasound was associated with an increased risk of bloodstream infections when guiding central line insertions at the femoral and jugular sites.20

To break the chain of infection transmission, every patient must be assumed to be infectious. Standardisation of disinfection processes and workflows is key to ensure compliance with Spaulding and protect patients from being exposed to infection risk.

Automation enables standardised POC disinfection

Probe disinfection at point of care should be successful every time to reproducibly protect the next patient from infection transmission. Reproducibility depends on meeting the clinical parameters required to achieve the disinfectant’s validated label efficacy claims on all surfaces of a probe. These parameters include contact time, mechanical effect (e.g. pressure applied when wiping), temperature, chemical concentration or dosage depending on the methods used.

Manual disinfection methods, such as wiping, are prone to human error.

Automated reprocessing eliminates the variables inherent in manual methods and establishes traceable, reproducible processes. Automated processes are also validated to achieve their expected performance outcomes consistently every time. In Germany, the Robert Koch Institute (RKI) has reported that they were unable to identify any standards or guidelines that demonstrated the validation of manual wipes as a final disinfection step for semi-critical devices.21,22 RKI identified that sufficient mechanical force and application of disinfectant to all surfaces and geometries of a device could not be guaranteed with wipes.

erman guidelines have recommended automation for the reprocessing of reusable semi-critical devices, including ultrasound probes, since 2012. Health authorities across Europe, including those in Germany, Belgium, Wales, Netherlands and Ireland, all recommend automation as a preferred solution for the reprocessing of reusable semi-critical devices like ultrasound probes.7,23-26 In a U.S. national survey of infection preventionists, 91% of respondents said they preferred to use automated processes for probe reprocessing.27

Figure 2. Snapshot of European guidelines on semi-critical medical device disinfection, including ultrasound probes.

The importance of traceability

A key consideration for point of care reprocessing is the keeping of essential documentation, including records of medical device reprocessing and patient procedures. The linking of reprocessing cycle records to a patient record is known as traceability. Guidelines in the UK and Ireland require medical devices classified as semi-critical and critical to have full traceability to the patient.7,10,11 The minimum dataset for a procedure record includes patient identifier, medical record number, procedure type, and operator for the procedure.7 For reprocessing, the minimum dataset required by guidelines includes transducer and serial number, cleaning and disinfection product serial numbers, date and time of disinfection, and operator.7

Because of its portability and use at point of care, ultrasound presents unique challenges for traceability. It is essential to have traceability documentation for decision making about device recalls or patient notifications in outbreak settings. In an outbreak of Serratia marcescens attributed to an ultrasound probe used in a digestive surgery ward, 8 out of 9 patients who came into contact with the contaminated probe were infected.19 Traceability records were instrumental in identifying previously missed cases. An investigation identified several lapses including the absence of terminal disinfection after cleaning, lack of sterile protective sheath use and the use of a damaged probe. Following corrective measures, including the implementation of traceability practices, no further S. marcescens infections were reported.19

In non-outbreak settings, traceability allows facilities to demonstrate that they have met their duty of care to patients.

Incorporating digitisation into traceability is the best way to ensure standardised information across the entire workflow. Digitisation can reduce manual administrative burden, the risk of operator error, and incomplete record keeping

Figure 3. Traceability involves linking both a reprocessing record and procedure record to a medical device. A suggested dataset to be collected and linked to the patient for every high-level disinfection cycle is presented here.

Safety considerations for POC reprocessing

Safety of point of care reprocessing systems is another key factor for consideration. The ideal disinfection technology for use at point of care is a closed system that requires minimal handling of the disinfectant, as this protects both patients and staff from being in contact with the active chemistry. Manual technologies, such as wipes, require direct handling of the disinfectant and the use of a rinsing step to remove residual chemicals from the surface of the probe. 

When appropriate risk assessments and safety measures are taken into account when designing clinical workflows, automated HLD technologies offer point of care disinfection with less hands-on time, that is safer for both patients and staff.

Streamlining POC disinfection workflows

One of the most important considerations for point of care reprocessing is the segregation of clean and dirty processes to prevent recontamination of clean probes. For manual disinfection processes, this is often achieved through segregation of clean and dirty areas with physical barriers or demarcation of zones.

In the patient room, the same outcome can be achieved by adopting a structured workflow. Under normal circumstances, the patient room becomes “dirty” during a patient stay or procedure and the room must be returned to a “clean” state ready for the next patient.

The use of automated technologies can streamline this segregation of dirty and clean processes. For example, handling of a dirty probe can occur only when the room is “dirty” (i.e. as the patient leaves the room), and handling of the clean probe then only occurs after the room has been turned over and is ready for the next patient (i.e. a “clean” state).

Furthermore, using single-use storage covers protects the probe by providing a barrier to contamination from handling and the environment. Use of these covers completes the clinical workflow for safe POC reprocessing.

Improving and standardising processes

The best way to ensure safe and effective reprocessing of ultrasound probes at point of care is through improvement and standardisation. UK and Irish experts in infection prevention and decontamination have developed a consensus document called the Ultrasound Infection Prevention Toolkit. This toolkit, available free of charge at www.ultrasoundinfectionprevention.org.uk is product agnostic and helps infection prevention staff locate ultrasound machines in their facility, conduct risk assessments, and develop or improve reprocessing policies. When taking into account key considerations around automation, traceability, safety and workflows, point of care reprocessing of ultrasound probes can help protect patients from infection risk.

References

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