Ultrasound infection prevention includes properly covering the transducer, eliminating the risks posed by ultrasound gel, and disinfecting the probe post-procedure.
Medical facilities exist to care for and improve the health of their patients, but a major concern for patients is the risk of contracting an infection during a procedure or hospital stay. Healthcare-associated infections (HAIs) are acquired while patients receive healthcare for another condition1 and can occur 48 to 72 hours after treatment.2
The European Centre for Disease Control and Prevention (ECDC) estimates that 8.99 million HAIs occur across Europe each year. Approximately one in 18 patients will be affected during their hospital stay. HAIs represent a common pathway to sepsis, which contributes to approximately 37,000 deaths annually. The annual cost of treating these infections is €7bn due to the resulting extended hospital stays, which total 16 million days.3
Healthcare-associated infections cause tens of thousands of deaths a year, many of which are preventable. Additionally, HAIs have become increasingly harder to treat as antibiotic resistance grows more prevalent. In 2016, the World Health Organization underscored: ‘Every infection prevented is an antibiotic treatment avoided.’4 A report from the US Centers for Disease Control and Prevention (CDC) shows 2.8 million people are made ill each year in the United States from pathogens which have learned to outsmart antimicrobial drugs: an increase of 800,000 per year since the previous report was issued in 2013.5
What causes healthcare-associated infections?
HAIs can be caused by bacteria, fungi, viruses, or other less common pathogens. Contamination can be caused by bacteria from a variety of sources common in a hospital or procedural setting:
- Ultrasound transducers
- Examination tables
- Ultrasound systems
- Door handles
- Ultrasound gel6
A 2016 survey of 946 clinicians, conducted by the European Society of Radiology, surmised that transmission of infection through ultrasound procedures is possible, as not all practitioners use probe covers for endocavity or interventional ultrasound and not all practitioners use sterile gel for internal or invasive procedures.7
A blind study demonstrated just how easily bacteria can spread around an ultrasound exam room. The researchers placed glow powder in several locations of the ultrasound suite and investigated primary (ultrasound system monitor, gel bottle, disinfecting spray bottle, etc) and secondary (other transducers, transducer cables, etc) surfaces after exam cleanup. They found that the gel bottle was the most frequently contaminated item.8
Can ultrasound gel lead to infections?
The external surface of a reusable gel bottle can be a source of bacteria, but ultrasound gel itself can also be a source of contamination. Most ultrasound gel is composed of propylene glycol and water and can inhibit the growth or reproduction of bacteria.9 When contaminated ultrasound gel enters a patient’s bloodstream during an ultrasound-guided intervention, it presents a risk of infection.
Published studies have outlined multiple cases of infection due to the use of contaminated ultrasound gel. Here are just a few examples of recent cases:
Outbreak of health care-associated Burkholderia cenocepacia bacteraemia and infection attributed to contaminated sterile gel used for central line insertion under ultrasound guidance and other procedures, The American Journal of Infection Control10
A 2017 outbreak of Burkholderia cenocepacia bacteraemia across four hospitals in Australia infected 11 patients, primarily in intensive care units (ICUs). Cultures from the affected patients were tested; and the source of the infection was determined to be single-use sterile ultrasound gel from procedure kits used in central line placements and other procedures, which was found to be heavily contaminated with Burkholderia cenocepacia. Each of the patients had undergone an ultrasound-guided intervention.
Outbreak of Burkholderia cepacian bacteraemia in a tertiary care centre due to contaminated ultrasound probe gel, Journal of Hospital Infection11
Two people died of septic shock after Burkholderia cepacian was found in the blood cultures of 14 patients at a Saudi Arabian hospital in 2016. All patients had central venous catheters placed. Multiple cultures were tested, and ultrasound gel sachets used in the procedures were identified as the source of the infections.
The authors of this study reported: ‘Products that are supposed to be sterile may become contaminated during the manufacturing process, leading to infections. Invasive procedures put patients at higher risk of infection, particularly immunocompromised ICU patients.’
Polyclonal outbreak of bacteraemia caused by Burkholderia cepacian complex and the presumptive role of ultrasound gel, The Brazilian Journal of Infectious Diseases12
The 2013 outbreak of Burkholderia cepacian complex (BCC) in Argentina affected11 patients who had undergone an average of five ultrasound procedures or examinations in the neonatal, intensive care, and general medical units. Samples were cultured from a variety of sources, including antiseptics, drugs, surgical room surfaces, and ultrasound gel, with the contamination traced to an unopened 5l container of ultrasound gel.
Pseudomonas aeruginosa respiratory tract infections associated with contaminated ultrasound gel used for transoesophageal echocardiography, Centers for Disease Control & Prevention (CDC)13
In 2011, seven patients were infected and nine were colonised with Pseudomonas aeruginosa following cardiovascular surgery with the use of transoesophageal echocardiography. After the Michigan facility noticed the increase of positive respiratory cultures in the ICU, an investigation found the source to be contaminated ultrasound gel. Cultures were found in both opened and unopened multiuse gel bottles.
How should ultrasound gel be managed?
Determine if ultrasound gel is necessary for the procedure or examination:
1) Gel-free viral barriers now exist for ultrasound
2) Envision™ probe covers and scanning pads are activated with sterile liquid and require no ultrasound gel. Cover the ultrasound probe or apply the scanning pad directly to the patient’s skin for safe scanning without gel:
a) Reduces the risk of contamination during central venous catheter (CVC) or peripherally inserted central catheter (PICC) line placements, scanning of wounds or non-intact skin, intraoperative imaging procedures, and other interventions
b) Workflow also improves: absence of gel results in quick setup and cleanup of the transducer.
If the use of gel is necessary, consider recommendations to minimise infection risk:
a) Use sterile gel with mucosal contact whether a biopsy is performed or not
b) Use open gel containers within a specified time frame, as outlined by facility policies
c) The Joint Commission requires an expiration date be marked on the bottle
d) Eliminate refilling or ‘topping off’ bottles. Discard original container after use or expiration
e) Monitor these practices
2) Health Canada:15
a) Establish guidelines on the use of ultrasound gel at your facility
b) Consider using single-dose, sterile gels
How to reduce the spread of infection in ultrasound
- Cover the ultrasound probe with a validated viral barrier. Probe covers inhibit the transfer of pathogens through probe contamination. Probe sheaths should have been designed, validated, and cleared for use as an ultrasound probe cover: though used by some as probe covers, condoms, bandages, or plastic bags have not been validated as probe covers
- Consider using a gel-free ultrasound probe cover or scanning pad, such as Envision
- When ultrasound gel must be utilised, use sterile, single-use packets, and remove from the site prior to puncture
- Cover the ultrasound system with a sterile drape.16
- Properly clean and reprocess the ultrasound transducer between patients. Guidelines vary – check with your facility’s infection control department as well as the ultrasound device manufacturer’s instructions for use
Increased awareness and improved policies and practices are needed to fight the spread of healthcare-associated infections. Signs of progress indicate current measures are helping.
Estimates indicate effective infection prevention and control programmes can lead to a reduction of more than 30% in HAI rates worldwide. In 2018, US hospitals observed 8% to 12% fewer central line bloodstream infections, catheter-associated urinary tract infections, and C. difficile infections compared to the 2017 national baseline.17
This is promising; and with continued research and education, investments in innovative products and solutions, and improved procedures and processes, we can achieve safer health outcomes for clinicians and patients.
To learn more about reducing the risks of infection in ultrasound, consider CIVCO Medical Solutions as a partner in those efforts. CIVCO’s mission is to make ultrasound-guided procedures safer. CIVCO is a leading provider of infection control solutions where ultrasound is utilised, from ultrasound viral barrier covers to ultrasound needle guidance to high-level disinfection of ultrasound transducers.
6 Westerway S, Basseal J, Brockway, Hyett A, Carter D. Potential Infection Control Risks Associated With Ultrasound Equipment – A Bacterial Perspective. Ultrasound in Med & Biol., Vol 43, No 2, 421-426 2017.
7 Nyhsen, Christiane et al. Infection prevention and ultrasound probe decontamination practices in Europe: a survey of the European Society of Radiology. Insights Imaging. 3 October 2016.
8 Pessin YJ, Matthews EP. (2019). Glow Powder: See the Germs? An Innovative Teaching Technique in a Student Sonography Laboratory. Journal of Diagnostic Medical Sonography, 35(5), 363–372. https://doi.org/10.1177/8756479319855006
10 Shaban R, et al Outbreak of health care-associated Burkholderia cenocepacia bacteraemia… American Journal of Infection Control 45 (2017) 954-8.
11 Abdelfattah R, Aljumaah S, Alqahtani A, Althawadi S, Barron I, Almofada S. Outbreak of Burkholderia cepacia bacteraemia in a tertiary care centre due to contaminated ultrasound probe gel.” Journal of Hospital Infection, 2017; pii: S0195-6701(17)30516-9.
12 Nannini, Esteban C, et al. Polyclonal Outbreak of Bacteraemia Caused by Burkholderia Cepacia Complex and the Presumptive Role of Ultrasound Gel. Brazilian Journal of Infectious Diseases, vol. 19, no. 5, Sept. 2015.
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