Exploring probe decontamination

Transoesophageal echocardiography (TOE) enables real-time visualisation of the heart via the stomach and oesophagus using ultrasonic emission from the distal end of a flexible probe. These probes do not have lumens and, due to the incorporation of unsealed electronic components, the probes are not fully submersible – only the patient insertion tube can be immersed in liquid. Being a semi-invasive procedure, the potential for transmission of infection between sequential patients does exist. Guidelines for disinfection during gastrointestinal endoscopy have been in place for many years.1, 2 However, similar guidance is lacking with respect to TOE, even though the procedure traverses the same body cavities and shares many similarities. The cleaning and decontamination of TOE probes, and other similar devices such as transrectal ultrasound (TRUS) probes and transvaginal ultrasound (TVUS) probes, that do not have internal lumens has, traditionally, been carried out manually immediately after use. This includes wiping the unit clean with detergent-soaked cloths or sponges, followed by wiping with a disinfectant- soaked cloth or sponge several times. The probe is then rinsed with water and dried. In 2011, guidelines were published in The European Journal of Echocardiography – Guidelines for Transoesophageal echocardiographic probe cleaning and disinfection from the British Society of Echocardiography3 – offering advice on ‘best practice’ for TOE probe decontamination. Although the authors found minimal evidence that there is a risk of crossinfection, they stated that the absence of such evidence should not be considered as evidence of the absence of risk. They went on to state that estimating the infection risk is difficult because there are no wellperformed comprehensive studies relating to infection control TOE practice and the onset of infections relating to procedures may be delayed until after the patient is discharged from hospital, making diagnosis and reporting unlikely.

Medical device alert

The issues surrounding probe decontamination was again highlighted when a Medicines and Healthcare products Regulatory Agency (MHRA) Medical Device Alert (MDA/2012/037) was produced in the Summer of 2012 relating to probe decontamination practice. This alert stated: “The MHRA is aware of an incident where the death of a patient from hepatitis B infection may have been associated with a failure to appropriately decontaminate a transoesophageal echocardiography probe between each patient use.” Action advised by the MHRA as a result was: “Review, and if necessary update, local procedures for all ultrasound probes that are used within body cavities to ensure that they are decontaminated appropriately between each patient use, in accordance with the manufacturer’s instructions and ensure that staff who decontaminate medical devices are appropriately trained and fully aware of their responsibilities.” During a presentation at an Infection Prevention Society (IPS) event at the end of September 2013, one of the authors of the 2011 guidelines,1 Christina Bradley, laboratory manager, Hospital Infection Research Laboratory at Queen Elizabeth Hospital Birmingham, touched on the issues surrounding probe decontamination. She said: “The 2011 guidelines for TOE probes were published as a result of an approach from cardiologists for guidance, which demonstrates that awareness of the issues surrounding probe decontamination are becoming more widely considered.