The results of a ground breaking study carried out in Scotland demonstrates that lack of scientific certainty is no longer a reason to postpone infection control measures for ultrasound reprocessing.
There are two main schools of thought when it comes to ultrasound reprocessing. There’s the growing number of ultrasound professionals who are adopting decontamination guidelines which recommend high level disinfection, while the second school of thought still believes that low level disinfection is suitable for all types of ultrasound procedures.
The latter group is now likely to find itself quickly moving towards high level disinfection methods due to the results of a groundbreaking epidemiological study which has global implications about the reprocessing methods used for transvaginal and transrectal ultrasound probes.
Undertaken by Health Protection Scotland and NHS National Services Scotland, this first population-level study of its kind demonstrated a greater risk of positive microbiological reports and antibiotic prescriptions within 30 days for adults who had undergone semi-invasive ultrasound procedures when high level disinfection was not used as the standard of care.1
The NHS Scotland Risk Based Recommendations for the Decontamination of Semi-Invasive Ultrasound Probes: Risk of infection following semi-invasive ultrasound procedures in Scotland, 2010 to 2016 study is available at the Health Protection Scotland website (www.hps.scot.nhs.uk).
During the study period, low level disinfection was the primary method used for the disinfection of endocavitary probes.
In relation to transvaginal ultrasound scans, the study found that in the 30 days after a scan, patients were 41% (HR=1.41) more likely to have positive bacterial cultures and 26% (HR=1.26) more likely to be prescribed antibiotics than similar patients who underwent gynaecological procedures without ultrasound (p<0.001).
For transrectal scans, patients were 3.4 (HR=3.4) times more likely to have positive bacterial cultures and 75% (HR=1.75) more likely to be prescribed antibiotics (p<0.001).
In conclusion, the study states: “Analysis of linked national datasets demonstrated a greater risk of positive microbiological reports and community antibiotic prescriptions within 30 days for Scottish adults who had undergone semi-invasive ultrasound procedures in Scotland.
“This indicates that, prior to the publication of NHS Scotland guidance advocating high level disinfection, the re-use of semi-invasive ultrasound probes without high level disinfection posed an increased risk of infection… failure to comply with guidance recommending high-level disinfection of semi-invasive ultrasound probes will continue to result in an unacceptable risk of harm to patients.”
Adherence to local guidelines
The study authors strongly recommend adherence to the 2016 NHS Scotland Guidance for Decontamination of SemiCritical Ultrasound Probes which calls for the high level disinfection of endocavitary ultrasound probes.2
Before the 2016 Scottish guidelines were implemented, a 2012 national survey revealed that only 9.5% of Scottish facilities were performing high level disinfection on semi-invasive probes.3
The 2016 guidelines require cleaning followed by high level disinfection for all semi-critical ultrasound probes. This includes semi-invasive transvaginal, transrectal and transesophageal probes as well as noninvasive probes used on non-intact skin surface probes during venepuncture, cannulation, and wound and cavity assessment procedures.
What’s more, during any non-invasive procedure, if blood or bodily fluids are noted, the ultrasound probe needs to be high level disinfected. Importantly, using a probe cover during a procedure does not negate the need to comply to the guidelines. Regarding disinfection methods, the guidelines recommend automated, validated technologies and traceability.
Ireland’s Health Service Executive has also modelled its February 2017 guidelines on those for Scotland. The guidelines note:
“HLD (high level disinfection) using the manual multiwipe system is the least preferred option for disinfecting SIUPs (semiinvasive ultrasound probes). Internationally it is recognised that the use of an automated validated process for decontaminating RIMD (reusable invasive medical devices) will provide enhanced risk reduction of infection transmission. It is recommended that a local risk assessment is performed if this option is to be used as an interim measure prior to implementation of an automated process.”4
In Wales, guidelines in the form of Welsh Health Technical Memorandum WHTM 01-06 were issued in 2014 for ultrasound probes and endoscopes. It is recommend that ultrasound probes preferably be disinfected with automated decontamination processes. Manufacturers of automated decontamination devices and manual procedures must provide evidence for reaching the claimed disinfection endpoints and this should be investigated during the procurement process. Furthermore, traceability should be incorporated in all reprocessing workflows.5
New European guidelines
To help prevent the risk of ultrasound infections caused by cross-contamination, the European Society of Radiology which is the world’s largest radiology society with 74,000 members worldwide, issued new ultrasound reprocessing guidelines in November 2017.
The guidelines strongly recommend high level disinfection for all interventional ultrasound and endocavitary ultrasound procedures.6
Like the Scottish study, the guidelines emphasise concerns about ultrasound probe contamination risks when only low level disinfection, and only probe covers are used, and is backed up by published evidence. In addition, the guidelines state that an automated hydrogen peroxide system such as trophon EPR is advised.
Also in 2017, the European Committee for Medical Ultrasound Safety (ECMUS) guidelines recommended that transvaginal, transrectal, transoesophageal and intraoperative probes undergo cleaning followed by high level disinfection before use on a new patient.
Automated, manufacturer validated processes are preferred as long as full documentation of the process is available.7 ECMUS is a committee of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB).
Move towards automated solutions
As awareness about the need to high level disinfect ultrasound probes is spreading quickly due to the issuance of local and international reprocessing guidelines, it is prompting a rethink by infection control and ultrasound professionals about the pros and cons of their disinfection methods. As a result many are moving to an automated high level disinfection system such as trophon EPR.
Bryn Tudor-Owen, the United Kingdom Country Manager for Nanosonics which manufactures trophon EPR, noted: “Many reprocessing staff are finding that automated high level disinfection systems such as trophon EPR are a more reliable and reproducible high level disinfection solution than traditional disinfection methods such as manual wiping and UVC exposure.
“Manual wiping can increase the risk of operator error as it relies on the operator to strictly adhere to manually wiping probes with a wipe for a prescribed number of minutes. Manual wiping also exposes the operator and patient to chemicals.”
He added that with UVC there is the problem of ultrasound probe shadowing due to cracks, crevasses, or parts of probes may have unusual contours for biopsy needle placement. These factors could result in the UVC light not being completely effective. Additionally UVC light may require two cycles to be effective against fungi (Aspergillus niger).
Commenting on the new Scottish study finding, Tudor-Owen, said: “It leaves no doubt about the risk to patients if semiinvasive ultrasound probes do not undergo high level disinfection.
“The good news is that since the 2016 Scottish guidelines came into force, trophon EPR is now the standard of care in many healthcare facilities because it’s effective and easy to use. Developed for point of care use, trophon safely eliminates an extensive range of infectious bacteria, fungi and viruses, including sexually transmitted infections such as the high-risk, cancer causing human papillomavirus.8 For staff, trophon is safe and simple to use with a one touch button operation. This means staff are protected from the hazards of traditional chemical methods such as usingchemical wipes. Importantly trophon EPR also offers the added advantage of an inbuilt traceability solution for auditing requirements.”
Health boards adopt trophon
Among the Scottish health boards to adopt trophon EPR are NHS Fife and NHS Western Isles. NHS Fife has six trophons for use at Kirkcaldy’s Victoria Hospital, five at Dunfermline’s Queen Margaret Hospital and one at St Andrews Community Hospital. Gill Rooney, Superintendent Sonographer at NHS Fife, said: “We wanted trophon to help with workflow and make the department even more efficient, and ensure we deliver a consistent decontamination process.
NHS Western Isles has two trophons. One at Stornoway for general and women’s health usage and the other for general use at Benbecula. Commenting on the switch from using disinfection wipes to trophon EPR, Jane MacDonald, Acting Radiology Manager, said: “Using wipes was a time consuming effort to decontaminate regular transvaginal probe use. It caused disruption to heavy ultrasound work lists and the shortening of lists to accommodate examinations.”
Simplified decontamination processes
MacDonald added that the trophon devices have simplified their decontamination processes. “For staff, trophon EPR is reliable,” she said. “Probes are always ready for use between patients, reducing examination times. We also have auditable proof of decontamination. What’s more, trophon’s visibility to patients gives them confidence in the cleanliness of the examination procedure.”
In summarising the reinforcement of high level disinfection by studies and guidelines Tudor-Owen concluded: “The Scottish study adds to the weight of evidence being used to support the development and implementation of further guidelines internationally. This is good for staff as they know exactly how to minimise the risk of cross-contamination that can occur with low level disinfection.”
* References for this story are available on request.
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