Increasing clinical evidence is highlighting the reprocessing risks for intracavity and surface ultrasound probes.
Probe handle risk
Effective high level disinfection should eliminate fungi, bacteria, and viruses on an ultrasound probe. Unfortunately, this does not always occur in clinical practice.
Sometimes the ultrasound probe handle is omitted from reprocessing because many ultrasound probes are not fully immersible. Immersion of the handle in bulk liquid chemistries can damage the probe, so users avoid disinfecting the handle.
While there is no specific guidance for ultrasound probe handle disinfection, a number of experts have noted it is imperative for the reprocessing guidelines to be updated.1,6
trophon safely and effectively treats both the probe body and handle, without risk of damage.
The frequency of handle contamination was also confirmed in another study showing that over 80% of handles had residual contamination (after probe reprocessing) where handles were not disinfected7.
These results are concerning when considered alongside ultrasound probe contamination rates. A meta-analysis has shown that 12.9% of intracavity transducers are contaminated with pathogenic bacteria following disinfection with low level disinfectant wipes or sprays.2 Multiple studies have shown that HPV DNA persists on transducers after disinfection with low level disinfectant wipes.3-5
Experts have discussed the potential for ultrasound probe handles to act as a reservoir for nosocomial pathogens, which could be transferred to the probe head, sheath or to a patient1,6. This research highlights the imperative need for guidelines and healthcare policies to be updated to ensure that the handle and probe are adequately disinfected after every patient use6.
- Ngu A, McNally G, Patel D, Gorgis V, Leroy S, Burdach J. Reducing Transmission Risk Through High-Level Disinfection of Transvaginal Ultrasound Transducer Handles. Infect Control Hosp Epidemiol. 2015;36(5):581-4.
- Leroy S. Infectious risk of endovaginal and transrectal ultrasonography: systematic review and meta-analysis. Journal of Hospital Infection (2012), http://dx.doi.org/10.1016/j.jhin.2012.07.014
- Casalegno et. Al.: High Risk HPV Contamination of Endocavity Vaginal Ultrasound Probes: An Underestimated Route of Nosocomial Infection?, PLOS ONE, Oct 2012, Volume 7, Issue 10
- Ma et al.: Transvaginal ultrasound probe contamination by the human papillomavirus in the emergency department, Emerg Med J, 2012
- M’Zali et al. Persistence of microbial contamination on transvaginal ultrasound probes despite low-level disinfection procedure. PLoS One 2014;9:e93368.
- Alfa MJ. Intra-cavitary ultrasound probes: cleaning and high-level disinfection are necessary for both the probe head and handle to reduce the risk of infection transmission. Infect Control Hosp Epidemiol. 2015;36(5):585-6.
- Buescher DL, Mollers M, Falkenberg MK, Amler S, Kipp F, Burdach J, et al. Disinfection of transvaginal ultrasound probes in a clinical setting: comparative performance of automated and manual reprocessing methods. Ultrasound Obstet Gynecol. 2016;47(5):646-51.
Probe sheath risk
Using a protective sheath or condom on an ultrasound probe does not negate the requirement for HLD.
Evidence shows that sheaths can have microscopic perforations before use and often have micro tears, increasing infection transmission risk. When using probe covers, HLD must still be applied7.
- Probe sheaths have been reported to break 25% – 81% of the time1
- Condoms used with transvaginal probes have been reported to break 0.9% – 5% of the time2-4
- Condoms used with transrectal probes have been reported to break 9% of the time5
The American Institute of Ultrasound in Medicine (AIUM) 2014 guidelines state:
“All internal probes should be covered with a single-use barrier. If condoms are used as barriers, they should be non-lubricated and non-medicated. Although internal ultrasound probes are routinely protected by single-use disposable probe covers, leakage rates of 0.9% to 2% for condoms and 8% to 81% for commercial probe covers have been observed in recent studies (Rutala and Weber, 2011). These probes are therefore classified as semi-critical devices.” 6
In 2008 the Centers for Disease Control and Prevention mandated that: “Even if probe covers have been used, clean and high-level disinfect”.7
Probe covers have a very high rate of perforation even before use.7
The Infect Control Hosp Epidemiol Journal states that probe covers “are inefficient at preventing contamination of endocavitary ultrasound probes under routine conditions”.8
- Highett M, Claman P. High rates of perforation are found in endovaginal ultrasound probe covers before and after oocyte retrieval for in vitro fertilization-embryo transfer. J Assist Reprod Genet. 1995;12(9):606-9.
- Amis S, Ruddy M, Kibbler CC, Economides DL, MacLean AB. Assessment of condoms as probe covers for transvaginal sonography. J Clin Ultrasound. 2000;28(6):295-8.
- Milki AA, Fisch JD. Vaginal ultrasound probe cover leakage: implications for patient care. Fertil Steril. 1998;69(3):409-11.
- Storment JM, Monga M, Blanco JD. Ineffectiveness of latex condoms in preventing contamination of the transvaginal ultrasound transducer head. South Med J. 1997;90(2):206-8.
- Masood J, Voulgaris S, Awogu O, Younis C, Ball AJ, Carr TW. Condom perforation during transrectal ultrasound guided (TRUS) prostate biopsies: a potential infection risk. Int Urol Nephrol. 2007;39(4):1121-4.
- American Institute of Ultrasound in Medicine. Guidelines for cleaning and preparing external and internal-use ultrasound probes between patients. AIUM Ofﬁcial Statement. Online at: http://www.aium.org/officialStatements/57
- Rutala WA, Weber DJ, HICPAC. Guideline for Disinfection and Sterilization in Healthcare Facilities. USA: Centers for Disease Control (CDC); 2008.Rutala W.A. et al., (Available at: https://www.cdc.gov/infectioncontrol/pdf/guidelines/disinfection-guidelines.pdf)
- Kac G, Podglajen I, Si-Mohamed A, et al. Evaluation of ultraviolet C for disinfection of endocavitary ultrasound transducers persistently contaminated despite probe covers. Infect Control Hosp Epidemiol 2010;31:165–17
Manual disinfection risk
Traditional ultrasound probe practices involving manual methods (such as soaking bulk liquid disinfectants) can be ineffective, inefficient, toxic and detrimental to the environment.
Manual processes can also be arduous for the operator, leading to a risk of error and a lack of compliance. Additionally, there is the risk of exposure to dangerous chemicals.
A substantial proportion of employees indicated they disliked manual reprocessing tasks, most felt a pressure to work quickly and most employees experienced health problems (including respiratory pain, tingling and numbness) attributed to reprocessing endocsopes.
Further, “automation resulted in better compliance with guidelines and reduced [health problems] associated with reprocessing.”
Employee compliance to HLD recommendations was observed as only 1.4% for manual methods versus 75.4% for an automated process.1
Manual disinfection of medical devices has been shown to lead to an increased risk of operator error if protocols are not followed correctly and poor protocol compliance can lead to an increased risk of transmission for patients.1,2
A non-fatal case of hepatitis C and a fatal case of hepatitis B have been linked to improper ultrasound transducer disinfection.3,4
- Ofstead, CL et al., Endoscope reprocessing methods: A prospective study on the impact of human factors and automation. Gastroenterology Nursing, 33:304–11, 2010.
- Weber DJ, Rutala WA. Assessing the risk of disease transmission to patients when there is a failure to follow recommended disinfection and sterilization guidelines. Am J Infect Control. 2013;41(5 Suppl):S67-71.
- Ferhi K, Roupret M, Mozer P, Ploussard G, Haertig A, de La Taille A. Hepatitis C transmission after prostate biopsy. Case Rep Urol. 2013;2013:797248.
- Medicines and Healthcare products Regulatory Agency (UK), Medical Device Alert Ref: MDA/2012/037
Health risks using traditional high level disinfectants
Ortho-phthalaldehyde (OPA) and glutaraldehyde (GTA) are both used as high-level disinfectants.
GTA and particularly OPA can pose severe health and safety risks for patients and clinical staff who are exposed. In addition to these health risks, both OPA and GTA have been shown ineffective against HPVs that can contaminate ultrasound probes (HPV 16).1
It was found in 2012 that nurses with regular daily exposure to sterilizing agents (including glutaraldehyde) during pregnancy, are more than twice as likely to undergo late spontaneous abortion compared to nurses who are not exposed to these chemicals.2
An earlier study showed detrimental effects upon embryo development when culture media were exposed to surgical instruments sterilized with Cidex.3
There is a body of published case reports showing workers and patients have experienced respiratory problems, anaphylaxis, skin reactivity, and systemic antibody production with use of OPA.4-9
- Meyers J, Ryndock E, Conway MJ, Meyers C, Robison R. Susceptibility of high-risk human papillomavirus type 16 to clinical disinfectants. J Antimicrob Chemother. 2014;69(6):1546-50.
- Lawson CC, Rocheleau CM, Whelan EA, Lividoti Hibert EN, Grajewski B, Spiegelman D, et al. Occupational exposures among nurses and risk of spontaneous abortion. Am J Obstet Gynecol. 2012;206(4):327 e1-8.
- Ackerman, S.B., et al., Toxicity testing for human in vitro fertilization programs. J In Vitro Fert Embryo Transf, 1985. 2(3): p. 132-7.
- H. Fujita, M. Ogawa, and Y. Endo. A case of occupational bronchial asthma and contact dermatitis caused by ortho-phthalaldehyde exposure in a medical worker,” J Occupational Health, vol. 48, pp. 413–416, 2006.
- W. N. Sokol. Nine episodes of anaphylaxis following cystoscopy caused by Cidex OPA (orthophthalaldehyde) high level disinfectant in 4 patients after cytoscopy. J Allergy and Clinical Immunology, vol. 114, pp. 392–397, 2004.
- Cooper DE, White AA, Werkema AN, Auge BK. Anaphylaxis following cystoscopy with equipment sterilized with Cidex OPA (ortho-phthalaldehyde): a review of two cases. J Endourol. 2008;22(9):2181-4.
- Suzukawa M, Yamaguchi M, Komiya A, Kimura M, Nito T, Yamamoto K. Ortho-phthalaldehyde-induced anaphylaxis after laryngoscopy. J Allergy Clin Immunol. 2006;117(6):1500-1.
- Suzukawa M, Komiya A, Koketsu R, Kawakami A, Kimura M, Nito T, et al. Three cases of ortho-phthalaldehyde-induced anaphylaxis after laryngoscopy: detection of specific IgE in serum. Allergol Int. 2007;56(3):313-6.
- Anderson SE, Umbright C, Sellamuthu R, Fluharty K, Kashon M, Franko J, et al. Irritancy and allergic responses induced by topical application of ortho-phthalaldehyde. Toxicol Sci. 2010;115(2):435-43.
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