Transducer Disinfection
Eric Liu
Senior Radiographer, Dept. of Imaging and
Interventional Radiology, Prince of Wales Hospital
Adjunct Associate Professor, Dept of Imaging and
Interventional Radiology, Chinese University of Hong
Kong
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Content
• Transabdominal transducer disinfection
• Transvaginal transducer disinfection
• Acoustic coupling gel infection risk
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Advantages of Ultrasound
examination
•
•
•
•
Non-invasive
Cheap
Dynamic examination
Repeatable
• Safe
Is it really safe without any risk ?
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
USG probe with gel on
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• In 13% of the procedures, the transducers are
contaminated with Staphylococcus aureus
• Two of 19 patients were shown to be infected as a
result of the procedure
• Evidence of cross-infection among patients
O’ Doherty AJ J Ultrasound Med 1989; 8: 610-620
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Message from literature
• A lot of pathogens exist in the used gel of the
transducer head
• The gel must be wiped off after use.
• Is wiping off the gel sufficient to clean
the transducer and protect the
patient ???
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
- Muradali et al (AJR 1995)
Single paper wipe was as effective as immersion
in chlorhexidine. However, Pseudomonas
Aeruginosa and MRSA could not be removed.
- Spencer and Spencer (Clin Radiol 1998)
Swabs taken from the transducers after they were
wiped with alcohol were sterile. Routine use of
alcohol wipe before the transducer was used to
scan any wound
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
- Tesch and Froschle (AJR 1997)
Many organisms were transmitted after a single
paper wipe and that immersion in glyoxal for 10
minutes was required to prevent growth.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
- Fowler and McCracken (Radiology 1999)
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•
•
Double paper wipe appears to be adequate for outpatients and fit short-stay inpatients
A single paper wipe followed by an alcohol wipe is adequate for patients at risk for
contracting infection (e.g. neonates or ICU patients)
Routine use of alocohol was not recommended due to risk of probe damage.
- Patterson and Monga et al. (Southern Medical J
1996)
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•
None of cultures from transducer heads were positive for pathogens.
Physical removal of the gel from the transducer head effectively eradicates the
microorganisms
- Karadeniz and Kilic et al. (Invest Radiol 2001)
Wiping the transducer with dry paper is effective only in abdominal scanning.
Cleaning the region with alcohol before scanning is necessary for inguinal and
axillary regions.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Message from Literature
• Paper wipe followed by alcohol wipe is the best method to
clean and disinfect the transducer.
• But routine use of alcohol was not recommended in the
past studies because of the fear of probe damage.
• Limitation of past studies
• Alcohol was used as disinfecting solution, which is known
to cause damage to transducer head.
• Some low-cost disinfecting solutions specially designed
for ultrasound transducers may avoid damage to the
transducer head.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• Use the disinfecting solution recommended by the
manufacturing company, probe damage is
minimized
• These are effective to kill most pathogens
including Hepatitis and HIV viruses.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• For General abdominal USG
Paper wipe of the transducer followed by spray of
disinfecting solution
When there is soiling of the transducer, cleanse with soap and
running water
• For dirty skin surface and USG-guided
FNA/Biopsy
Use Cling film or probe cover to decrease the degree of
contamination
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Transvaginal Transducer Disinfection
Condoms are used as the probe cover.
• Body secretion / blood are separated from the
transducer head by the condom (barrier)
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• Is it safe ?
• How often does it
rupture ?
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• 2% of condoms leaked, 65% were at distances that
could have led to probe soiling intravaginally.
• Perforations were noted in close, and even
consecutive scans. This indicated the needs for
routine probe disinfection.
Milki AA Fertility and Sterility, 1998; 69: 409-411
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Message from past studies
• Condom is useful to act as barrier during TV
procedures, but is not reliable to prevent infection.
• Additional transducer disinfecting procedure is
deemed necessary.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
AIUM & ASUM – Guidelines for
preparing Endocavity ultrasound
transducers between patients
1. Cleaning
- Removal of probe cover
- Use running water to remove any residual gel
or debris
- use liquid soap to thoroughly cleanse the
transducer
- consider the use of small soft brush especially
for crevices of the transducer
- Rinse the transducer with running water, and
dry it
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
- Cleaning with detergent / water solution is the
most important step. Meticulous cleaning is the
essential key to an initial reduction of microbial
/organic load by at least 99%.
2. Disinfection
-Additional use of high-level liquid disinfectant
will ensure further statistical reduction in
microbial load.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• Examples of high-level disinfectants include:
- 2.4 -3.2% glutaraldehyde products (Cidex,
Metricide, Pocide)
- Non-glutaraldehyde agents (Cidex OPA, Cidex
PA)
- 7.5% Hydrogen Peroxide solution
- 5.25% sodium hypochlorite (1:100 household
bleach)
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• AIUM and ASUM guidelines are good to clean and
disinfect the transducers, and to protect the patients from
cross-infection
• The guidelines are impractical and difficult to follow in
some or even most clinical settings.
• The most difficult step is the high-level disinfection.
• If the transducers can be disinfected with sodium
hypochlorite or hydrogen peroxide, the procedure is more
practicable (Unluckily, most transducers not compatible
with these!!)
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• Most transducers can only be disinfected by Cidex
or Cidex OPA.
• Cidex is considered toxic chemical and inhalation
may cause health problems
• According to OSH (Occupational Safety and
Health) rules, Cidex can only be manipulated in a
room with strong ventilation and the operator in
full PPE (personal protective equipment).
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Any suggestions
• Try to find the TV transducer which can be
disinfected with household bleach.
• Think of a practicable approach.
Please be reminded that the use of soap water to
cleanse the transducer is the most important step
(mircrobial load reduction by 99%)
Consider to use other disinfecting solution ??
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Acoustic coupling gel
• Several cases of bacteremia and septicaemia were
found to be originated from the ultrasound and
medical gels used during various procedures.
• Gel is good medium for pathogens to grow.
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• 6 adults and two neonates contracted Klebsiella
pneumoniae, and were found to caused by the
acoustic coupling gel
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
萬年油
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
萬
年
膏
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Key recommendation
• Gel bottles should not be “topped up”
• If resuable containers are used, they must be emptied first,
and rinsed with soap water thoroughly.
• Sterile gel must be used for all invasive procdures
• Sterile gel must be used for procedures on intact mucous
membranes (e.g. rectal and vaginal).
• Aseptic techniques should be followed when using sterile
gel.
• Warmed gel should only be used when required
• Kept in dry area and away from possible contamination
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
Conclusion
• USG can only be safe provided that the medical
professionals perform the examinations with
CLEAN transducers
• Transabdominal transducer disinfection
Wipe off the gel with paper followed by spray of
disinfecting solution for all patients
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
• Transvaginal transducer disinfection
- Follow the AIUM or ASUM disinfection
guidelines
- (use soap water to cleanse the transducer and
rinse it with water is cornerstone of the procedure)
• Acoustic coupling gel
- Don’t top up the gel bottle.
- Wash the bottles regularly
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong
ZERO INFECTION
零感染
Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong