When to HLD

Learn when to perform High Level Disinfection (HLD) of ultrasound probes.

The Spaulding Classification is the universal framework used by Federal authorities and professional societies to determine the minimum level of disinfection for reusable medical devices, including ultrasound probes (Table 1).

Table 1: Overview of The Spaulding Classification.1-7

Spaulding Classification

Medical Device Contacts

Risk of Infection Transmission

Disinfection Level


Sterile tissue or the bloodstream




Mucous membranes or non-intact skin


High Level Disinfection (HLD)


Intact skin only


Intermediate level (ILD)


Low level disinfection (LLD)

* Critical ultrasound probes can be high level disinfected and used with a sterile sheath if sterilisation is not possible.6,7

HLD must be used for critical ultrasound probes if sterilisation is not possible, a sterile sheath must also be applied to the probe.

Ultrasound probes are delicate, heat sensitive medical devices that cannot undergo steam sterilisation. Low temperature sterilisation methods require the probe to be out of circulation for extended periods of time, disrupting clinical workflow. 

Critical probes can be high level disinfected if sterilisation is not possible, however the probe must also be covered with a sterile sheath at use.

"RMDs that come into contact with sterile body cavities or are used on the critical aseptic field during invasive procedures shall be considered critical medical devices. These RMDs shall be reprocessed to the highest possible level between uses on individual patients in accordance with the manufacturer’s reprocessing instructions.

Cleaning, disinfection or sterilization, as appropriate, of RMDs shall be performed between uses even if a single use sheath/sleeve/protective barrier is used. Single use sheaths/sleeves/protective barriers for RMDs shall not be used as a substitute for cleaning, disinfection or sterilization."

"Transducers are extremely delicate and heat sensitive and as such are reprocessed as a semi‐critical medical device by cleaning followed by a HLD method as described in Section ‘High‐level disinfection’. An appropriate sterile sheath or transducer cover is applied, allowing it to be used on the critical aseptic field (AS/NZS4187:2014 Clause 5.1.3 (e))."

Probes that risk contact with sterile tissue or the bloodstream are critical, and include probes used in:

  • Surgery
  • Ultrasound guided percutaneous interventions where the probe may contact the sterile puncture site (e.g. drainages, injections, biopsies)
  • Scans across open wounds (e.g. surgical wounds, skin avulsion, 2nd or 3rd degree wounds)
HLD is minimally required for semi-critical ultrasound probes, a sheath must also be applied to the probe.

"Instruments used in semi-critical sites (e.g. intracavity probes such as transvaginal, transrectal or transoesophageal probes) require cleaning in accordance with manufacturer’s instructions and either sterilization (if possible) or high level disinfection."

"Ultrasound transducers that come into contact with non‐intact skin and /or mucous membranes...are considered as semi‐critical medical devices due to the high risk of potential contamination. These transducers are reprocessed by cleaning followed by a high‐level disinfection (HLD) method as described in Section 7.2 ‘High‐level disinfection’."

Probes that risk contact with mucous membranes or non-intact skin are semi critical, and include probes used in:

  • Transvaginal scans
  • Transrectal scans
  • Scans across rash, dermatitis or 1st degree burns
HLD can optionally be used for non-critical probes, however low level disinfection is sufficient.

Non-critical probes will only contact healthy, intact skin. Low level disinfection (LLD) is sufficient for these probes. However, optionally performing HLD ensures the probe is ready for any subsequent procedure.

Learn about HLD with the trophon®2 device. The trophon2 device can integrate with the range of clinical workflows to help keep your patients safe from cross-infection. 

Over 1,000 probes from 25 manufacturers are tested, approved and endorsed for use with trophon devices. View the probe compatibility list.

Following these guidelines and standards are essential in the fight against healthcare-associated infections (HAIs).

ANZ Guidelines

Read the HLD requirements for endocavitary and critical ultrasound probes

The trophon2 device HLD solution

Read about the recommended guidelines and standards in ANZ


The trophon® family includes trophon® EPR and trophon®2 which share the same core technology of 'sonically activated' hydrogen peroxide.


  1. Spaulding EH (1968). Chemical disinfection of medical and surgical materials. Disinfection, sterilization, and preservation. Lawrence C, Block SS. Philadelphia (PA), Lea & Febiger: 517-531.
  2. Australian Commission on Safety and Quality in Health Care (ACSQHC). National Safety and Quality Health Service Standards (NSQHSS). 2 ed. Sydney, Australia: ACSQHC; 2017.
  3. National Health and Medical Research Council (NHMRC). Australian Guidelines for the Prevention and Control of Infection in Healthcare. Canberra, Australia: NHMRC; 2019.
  4. Standards Australia (AS), Standards New Zealand (NZS). 4187:2014 Cleaning, disinfecting and sterilizing reusable medical and surgical instruments and equipment, and maintenance of associated environments in health care facilities. 2015.
  5. Standards Australia (AS), Standards New Zealand (NZS). 4815:2006 Office-based health care facilities - Reprocessing of reusable medical and surgical instruments and equipment, and maintenance of the associated environment. 2006.
  6. Australasian College for Infection Prevention and Control (ACIPC), Australasian Society for Ultrasound in Medicine (ASUM). Guidelines for Reprocessing Ultrasound Transducers. Australasian Journal of Ultrasound in Medicine. 2017;20(1):30-40.
  7. College of Intensive Care Medicine of Australia and New Zealand (CICM). Prevention of pathogen transmission during ultrasound use in the Intensive Care Unit: Recommendations from the College of Intensive Care Medicine Ultrasound Special Interest Group (USIG). Date accessed: 14th of May 2020.
Best Practice HLD