Transducer Disinfection

Department of Diagnostic Radiology and Organ Imaging, The Chinese University of Hong Kong

Transducer Disinfection

Eric LiuSenior Radiographer, Dept. of Imaging and

Interventional Radiology, Prince of Wales HospitalAdjunct Associate Professor, Dept of Imaging and

Interventional Radiology, Chinese University of Hong Kong


Content

• Transabdominal transducer disinfection

• Transvaginal transducer disinfection

• Acoustic coupling gel infection risk


Advantages of Ultrasound examination

• Non-invasive• Cheap• Dynamic examination• Repeatable

• Safe Is it really safe without any risk ?


USG probe with gel on


• 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



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 ???


- 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


- 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.


- Fowler and McCracken (Radiology 1999)• 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)

• 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.


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.


• 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.


• For General abdominal USGPaper 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


Transvaginal Transducer Disinfection

Condoms are used as the probe cover. • Body secretion / blood are separated from the

transducer head by the condom (barrier)


• Is it safe ? • How often does it rupture ?


• 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



• Condom is useful to act as barrier during TV procedures, but is not reliable to prevent infection.

• Additional transducer disinfecting procedure is deemed necessary.

Message from past studies


AIUM & ASUM – Guidelines for preparing Endocavity ultrasound

transducers between patients1. 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


- 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.


• 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)


• 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!!)


• 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).



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 ??


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.


• 6 adults and two neonates contracted Klebsiella pneumoniae, and were found to caused by the acoustic coupling gel


萬年油


萬年膏


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


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


• 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


ZERO INFECTION

零感染

Documents

Transducer Disinfection