10 May 2023

When verifying the safety of invasive transvaginal examinations, every possible preparation must be taken to eliminate chances of spreading pathogens. A reproducible method of manual disinfection that can be shown to reduce the risk of spread can help significantly with the overall safety of these common processes. Hartmann’s approach offers a potential solution.

Examinations with transvaginal ultrasound probes (TVUP) are routinely performed in gynecological and obstetrical practice. Even though, during use, the probe is usually covered by a protective sleeve, TVUP can pose a significant risk of spreading pathogens from patient to patient, if covers tear or the operator has contact with uncovered contaminated surfaces. If TVUP are not sufficiently reprocessed between uses, they can spread a variety of different pathogens like human papilloma virus (HPV), fungi, chlamydia, Streptococci, Staphylococci and fecal bacteria. Therefore, a reprocessing method requires virucidal, levurocidal, fungicidal, and bactericidal activity.

Several methods allow disinfection of TVUP, like immersion disinfection or machine-based processes, which both first require manual cleaning. Manual wipe disinfection is often the preferred option, as it is quick, easy, inexpensive and flexible. It also combines manual cleaning and disinfection. Immersion disinfection and machine-based processes often mean increased wear and tear or increased costs, as new probes often require new machinery.

Most importantly, regardless of the utilised reprocessing method, its efficacy has to be ensured for the patient’s safety. As manual reprocessing with ready-to-use tissues (RTU) has recently been deemed as non-validatable in Germany for the reprocessing of semi-critical devices of category A but is still frequently preferred in gynecologic practices and clinics, a procedure using RTU has been developed to help facilities validate their manual reprocessing methods.

To this end, three representative TVUP were contaminated with a high load of clinically relevant representative germs (polyomavirus SV40 strain 777 – to test for virucidal activity; Candida albicans – to test for levurocidal activity; Enterococcus hirae and Staphylococcus aureus – to test for bactericidal activity). For wipe disinfection three Mikrobac Virucidal Tissues (BODE Chemie GmbH, Hamburg, Germany) and one sampling swap were used per TVUP.

A reproducible and validatable method has to cover the whole device, including areas and parts that are difficult to access. After contamination of a single probe at two distinct areas, three Mikrobac Virucidal Tissues were used to wipe the probes in a standardised manner, starting at the handle. This step also provided mechanical cleaning if sufficient force was used. For machinebased or immersion disinfection mechanical cleaning is necessary before the disinfection. Further, cavities on the TVUP that are notoriously difficult to reach, were disinfected using a swab and the disinfectant pressed from one Mikrobac Virucidal Tissue.

After disinfection, the germ load in the two contaminated areas of all three probes was investigated. This procedure was repeated multiple times for all three probes. With the standardised method presented, a mean reduction factor of ≥5 log for bacteria and ≥4 log for yeasts and viruses was reached. These results demonstrate that, using a standardised method for mechanical disinfection, ≥ 99.9% of bacteria and ≥ 99.9% of yeasts and viruses on TVUP can be inactivated reliably.

By specifying the wiping time and procedure as well as the number of wipes, a valid manual wipe disinfection method is given, which can be used to validate the procedure on site after a risk assessment by the operator and enables hygienically safe reprocessing and documentation. Use biocides safely. Always read the label and product information before use.

Exemplary transvaginal ultrasound probe contaminated with pathogens for the disinfection test.

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