When to HLD

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

When to HLD

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

The Spaulding Classification indicates when to perform high level disinfection (HLD). The Spaulding Classification is the universal framework used by National health 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.1-6

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.4,5 In Scotland and Ireland, critical probes to guide needles or scan wounds are considered semi-critical.2,3

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.

"All critical probes (probes contacting sterile tissues or blood) should be preferably sterilised, but if sterilisation is not possible, they should be minimally high-level disinfected and used with a sterile sheath.”

"Consequently any US-assisted invasive procedure or any procedure potentially causing micro-trauma to the skin or mucous membranes has to be categorised as critical."

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.

“Semi-critical probes contact mucous membranes and noninvasive probes contacting non-intact/broken skin should be high-level disinfected either manually or with automated systems even if a sheath is used.”

"Under the Spaulding Classification Ultrasound Probes that come into contact with broken skin or intact mucous membranes are considered semi‐critical devices and should undergo manual cleaning followed by High Level Disinfection (HLD) between patient use."
"However the advancement of ultrasound scanning means they are increasingly used for scanning the skin which can be broken through the insertion of vascular devices or for the assessment of complex wounds.This increases the risk of contamination of the probe with blood which requires a high level disinfection process." 

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).

UK and European Guidelines

Read about guidelines on reprocessing semi-critical and critical ultrasound probes.

The trophon2 device HLD solution

Learn when to perform HLD. 


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. Health Protection Scotland (HPS), Health Facitlities Scotland (HFS), National Services Scotland (NHS) 2016. NHSScotland Guidance for Decontamination of Semi-Critical Ultrasound Probes; Semi-invasive and Non-invasive Ultrasound Probes. Version 1.0. March 2016.
  3. Health Service Executive (HSE) Quality Improvement Division 2017. HSE Guidance for Decontamination of Semi‐critical Ultrasound Probes; Semi‐invasive and Noninvasive Ultrasound Probes. Document: QPSD-GL-028-1.
  4. Society and College of Radiographers (SCoR) and British Medical Ultrasound Society (BMUS) 2019. "Guidelines For Professional Ultrasound Practice." Revision 3, December 2018.
  5. European Society of Radiology (ESR) 2017. Infection prevention and control in ultrasound - best practice recommendations from the European Society of Radiology Ultrasound Working Group.
  6. WHTM 01-06. 2014- Decontamination of flexible endoscopes Part C: Operational management, NHS Wales Shared Services Partnership – Specialist Estates Services: 74.
Best Practice HLD