Unbottling the Risks of Ultrasound Beyond the Probes
What is lurking inside ultrasound gel?
From May to September 2021, an outbreak of Burkholderia stabilis was linked to multiple lots of contaminated nonsterile ultrasound gel [1]. A total of 119 infections were associated with the Eco-Med Pharmaceutical product. Should every percutaneous procedure require single-use, sterile gel [2]? Some studies have demonstrated no difference in ultrasound-guided intravenous line placement versus traditionally placed lines by anatomical landmarks [3]. Beyond the ultrasound probe, ultrasound gel require special considerations in its safe use. What are the indications for single-use sterile gel versus a reusable bottle? Surprisingly, single-use, sterile packets of ultrasound gel are not commonplace, even among cardiothoracic anesthesiologists performing transesophageal echocardiograms [4]. How long should providers keep using a multidose bottle? Does warming ultrasound gel create a nidus for infection?
When do we need sterile gel?
According to the Spaulding Criteria, noncritical probes that contact intact skin and not mucous membranes only require low-level decontamination [5]. However, sanitation and hygiene become more stringent with critical or semi-critical probes that come into contact with non-intact skin or mucous membranes. Beyond high-level decontamination, these ultrasounds may also require the use of sterile gel. Currently, the American Institute of Ultrasound in Medicine (AIUM) has inexact recommendations on the use of sterile gel, encompassing but not limited to “all invasive procedures that pass a device through tissue; all ultrasound examinations performed on neonates; and all ultrasound examinations or procedures performed on non-intact skin or near fresh surgical sites [6].” It also suggests consideration of sterile gel for “endocavitory examinations on intact mucous membranes.”
Reusable, nonsterile gel can be difficult to manage, as practices will vary in the amount of gel used and bottle size. There are no recommendations on when to replace these containers. Current AIUM recommendations are basic—appropriately seal the container when not in use, discard when empty, and avoid direct contact between the container and persons or instrumentation [5]. Multidose containers used with patients under droplet or contact precautions should not be reused. This probably comes as no surprise to most providers.
What about warming gel?
Observational studies have not shown consistent associations of warming ultrasound gel and bacterial contamination. One study of 212 samples showed no growth of organisms while incubated at 37°C [7]. Another observational study demonstrated increased contamination in bottles stored between 20°C-40°C [8]. Another observational study showed growth within ultrasound gel bottles stored at 42°C.9 Should we be warming gel for our patients?
AIUM recommends only dry heat to warm gel, but defaults to manufacturer instructions and facility infection control policies.6 However, international recommendations differ. The United Kingdom Health Security Agency (UKHSA) and Health Canada’s Infection Prevention and Control of Canada (IPAC) Position Statement do not recommend warming gel unless the clinical benefit outweighs applying gel at room temperature [10,11]. The Australasian Sonographers Associations (ASA) also recommends against warming gel due to the risk of bacterial contamination and growth.
Does warming gel ever produce clinical benefit?
Probably not. However, patient comfort is a key component for a great patient experience, and as long as we are not harming the patients, we should keep them as comfortable as possible. How can we modify our practice to align with guidelines, while maintaining patient safety and comfort? It’s probably best to use gel warmer for multidose bottles if performing ultrasound on intact skin only (no mucous membranes) to improve patient comfort.
Consider the Cost
A 0.25-liter bottle of commonly used ultrasound gel (Aquasonic 100) is approximately 227 grams, while a single-use nonsterile packet is approximately 20 grams. A multidose bottle retails at $3.49, while a single-use nonsterile packet is approximately $0.36 per packet (sold in boxes of 100) [12]. There are approximately 11 times as much gel in a bottle, while the bottle costs approximately 10 times as much. The cost per gram for bottle vs. packet is comparable. However, a multidose bottle will last way more than 11 times. The bottom line, multidose bottles are more cost-effective.
The price is higher for a single-use sterile Aquasonic 100 packet and retails for $74.99 for 48 20g packets. That’s $1.5 per packet.
Here is a tip to save costs on single-use gel for ultrasound-guided IV placement. Use the good old Surgilube! It comes out to 15 cents per 3g packet if ordered in bulk (10 times less than the 20g single-use sterile packet above). Usually, one Surgilube packet is more than enough for ultrasound-guided IV placement.
Beyond the Basics
Should practitioners just wait until the CDC recalls another batch of contaminated gel [13]? After the 2021 B. stabilis outbreak, the CDC amended recommendations to include “avoiding use of bottles of nonsterile ultrasound gel for visualization prior to procedures.” Reports of contaminated ultrasound gel have stretched beyond the US. Canada addressed its own outbreak of bacteremia with new guidelines in 2004 of sterile gel for all invasive procedures and all procedures in the neonatal intensive care unit [11]. Similar to the US, sterile gel should be considered for procedures involving intact mucous membranes.
There are alternative methods to maintain sterility and hygiene when implementing ultrasound into clinical practice. Reusable gel bottles can be discarded a month after opening [10, 11]. Some practitioners follow guidelines to have gel “dispensed into a medicine cup or on a clean disposable cloth and then to the patient’s skin [11].” Integrating adequate and effective infection control measures requires assessment of facility resources and clinical scope of practice. While it may not be feasible or sustainable to reuse disposables with every scan, the dispensing nozzle can be cleaned with an alcohol swab, and the container disinfected between patients. Tailoring an approach to ultrasound safety extends beyond the machine, and entails all the facets of each unique clinical practice.
What does all of this mean for your practice?
Use sterile, single-use gel for any critical probes. Use single-use sterile gel for US-guided IVs. It’s best practice to use single-use nonsterile gel for skin with wounds/cellulitis.
It’s most cost-effective and least wasteful to use 3g Surgilube packets for US-guided IVs.
Scanning mucous membranes? It’s best to stick with sterile gel!
Discard multidose bottle after one month. Write a “discard by date” each time you start a new bottle.
Use gel warmer for multidose bottles only if scanning intact skin (no mucous membranes).
Keep the gel bottle on the device (NOT on patient’s bed!) and clean it in between patients.
Download the Spaulding Classification graphic here.
Authored by Jason Wang DO, MBS
References
Hudson MJ. Outbreak of Burkholderia stabilis Infections Associated with Contaminated Nonsterile, Multiuse Ultrasound Gel — 10 States, May–September 2021. MMWR Morb Mortal Wkly Rep [Internet] 2022 [cited 2023 Aug 31];71. Available from: https://www.cdc.gov/mmwr/volumes/71/wr/mm7148a3.htm
Healthcare Equipment | Disinfection & Sterilization Guidelines | Guidelines Library | Infection Control | CDC [Internet]. 2019 [cited 2023 Aug 31];Available from: https://www.cdc.gov/infectioncontrol/guidelines/disinfection/healthcare-equipment.html
Adhikari S, Blaivas M, Morrison D, Lander L. Comparison of infection rates among ultrasound-guided versus traditionally placed peripheral intravenous lines. J Ultrasound Med Off J Am Inst Ultrasound Med 2010;29(5):741–7.
O’Rourke M, Levan P, Khan T. Current Use of Ultrasound Transmission Gel for Transesophageal Echocardiogram Examinations: A Survey of Cardiothoracic Anesthesiology Fellowship Directors. J Cardiothorac Vasc Anesth 2014;28(5):1208–10.
Guidelines for Cleaning and Preparing External- and Internal-Use Ultrasound Transducers and Equipment Between Patients as Well as Safe Handling and Use of Ultrasound Coupling Gel [Internet]. www.aium.org. [cited 2023 Sep 23];Available from: https://www.aium.org/resources/official-statements/view/guidelines-for-cleaning-and-preparing-external--and-internal-use-ultrasound-transducers-and-equipment-between-patients-as-well-as-safe-handling-and-use-of-ultrasound-coupling-gel
Guidelines for Cleaning and Preparing External- and Internal-Use Ultrasound Transducers and Equipment Between Patients as Well as Safe Handling and Use of Ultrasound Coupling Gel [Internet]. Assoc. Med. Ultrasound. 2022 [cited 2023 Aug 31];Available from: https://www.aium.org/resources/official-statements/view/guidelines-for-cleaning-and-preparing-external--and-internal-use-ultrasound-transducers-and-equipment-between-patients-as-well-as-safe-handling-and-use-of-ultrasound-coupling-gel
Provenzano DA, Liebert MA, Steen B, Lovetro D, Somers DL. Investigation of current infection-control practices for ultrasound coupling gel: a survey, microbiological analysis, and examination of practice patterns. Reg Anesth Pain Med 2013;38(5):415–24.
Spratt HG, Levine D, Tillman L. Physical therapy clinic therapeutic ultrasound equipment as a source for bacterial contamination. Physiother Theory Pract 2014;30(7):507–11.
Westerway SC, Basseal JM, Brockway A, Hyett JA, Carter DA. Potential Infection Control Risks Associated with Ultrasound Equipment - A Bacterial Perspective. Ultrasound Med Biol 2017;43(2):421–6.
Good infection prevention practice: using ultrasound gel [Internet]. GOV.UK. [cited 2023 Sep 27];Available from: https://www.gov.uk/government/publications/ultrasound-gel-good-infection-prevention-practice/good-infection-prevention-practice-using-ultrasound-gel
Government of Canada HC. Archived – Serious Risk of Infection From Ultrasound and Medical Gels – Revision - Recalls, advisories and safety alerts – Canada.ca [Internet]. 2021 [cited 2023 Sep 26];Available from: https://recalls-rappels.canada.ca/en/alert-recall/archived-serious-risk-infection-ultrasound-and-medical-gels-revision
Aquasonic 100 Ultrasound Gel [Internet]. [cited 2023 Oct 12];Available from: https://aquasonicgel.com/aquasonic-100
Outbreak of Burkholderia cepacia Infections Associated with Contaminated Ultrasound Gel | HAI | CDC [Internet]. 2021 [cited 2023 Sep 26];Available from: https://www.cdc.gov/hai/outbreaks/b-cepacia-ultrasound-gel/index.html