- Published 30 Oct 2025
- Last Modified 30 Oct 2025
- 8 min
The Three Levels of Medical Device Decontamination
Medical device decontamination: cleaning, disinfection, and sterilisation for patient safety and compliance.
Medical device decontamination is the system for removing microbes from reusable medical objects and devices. Contamination can occur through airborne infection (where pathogens are suspended in the air, sometimes travelling through ventilation systems), droplets (where the pathogens travel a short distance and then settle), and contact transmission (where an infection occurs through direct contact with a pathogen or pathogen-laden surface). Defective decontamination practices can lead to an increased risk of infection.
In the 2024/2025 period, the MHRA assessed around 56,000 medical device incidents, taking action where necessary.
Why Decontamination Matters in Medical Device Design
Correct decontamination of medical devices can ultimately save lives by preventing the spread of infectious and potentially fatal diseases. When contaminated medical devices cause an infection, it’s referred to as a Healthcare-Associated Infection (HAI).
HAIs are a significant issue in the healthcare industry, and in Intensive Care Units (ICUs) in particular. The risk of a patient getting an HAI is between5 and 10 times higher when in an ICU due to:
- Compromised immunity (through life-threatening illness, open wounds, and invasive procedures)
- Environments crowded with medical devices are susceptible to contamination through direct patient shedding or via healthcare workers’ hands
- The presence of resistant pathogens common in ICUs
The WHO offers some hard-hitting stats around the prevalence of HAIs. In high-income countries, 7 out of every 100 acute-care patients will get at least one HAI during their stay. In low-income countries, this rises to 15 in every 100 acute-care patients. Of these, 1 in 10 will die due to their infection.
HAIs directly linked to medical device contamination are equally significant. The European Centre for Disease Prevention and Control reported that, in 2021, 15.6% of EU patients in an ICU for more than 2 days presented with an HAI. Of these:
- 10% contracted pneumonia, and in 66% of cases, the infection was linked to intubation
- 8% suffered a bloodstream infection, and in 38% of cases, this arose through catheterisation
- 4% suffered a UTI, 97% of infections were caused by a catheter
The COVID-19 pandemic also brought the risk of HAIs and the critical importance of medical device contamination into sharp focus.
The patient volumes and unprecedented demand for reusable medical devices such as ventilators, oxygen masks, and tubing, combined with supply chain pressure for these devices, overwhelmed health services and increased strain on cleaning protocols, created the perfect storm for cross-contamination.
What are the Three Levels of Decontamination of Reusable Medical Devices?
Decontamination requirements differ depending on how a medical device is used and the infection risk posed.
The potential infection risk is split into three levels, which are based on Earle Spaulding’s framework, originally devised in 1939 and cemented into the Spaulding Criteria in 1957.
The Spaulding Classifications are:
- Critical - Devices that penetrate skin tissue, such as surgical tools, probes, or implants, for example, must be sterilised after each use
- Semi-critical - Devices that make contact with mucous membranes or broken skin, such as the moist linings of the nose or mouth, for example, must, at a minimum, be disinfected between uses. If there is a risk of skin penetration, as might be the case with gynaecology tools, full sterilisation (the higher tier of decontamination) is required
- Non-critical - Devices that make contact with the skin but do not penetrate it, such as blood pressure cuffs, require the basic level of cleaning
These levels directly correspond to the following decontamination requirements, creating a hierarchy of needs based on the infection risk.
- Critical devices = Sterilisation (highest level)
- Semi-critical devices = Disinfection (middle level)
- Non-critical devices = Cleaning (lowest level)
Triaging in this way allows healthcare services to prioritise effectively, based on need. This is particularly important when the decontamination demands are complex and time-consuming.
Level 1: Cleaning – The First Line of Defence
Cleaning is a step that always happens before disinfection and sterilisation. This step is never leapfrogged just because a higher tier of decontamination is required. This is because cleaning involves removing visible soiling and organic matter, which may block or reduce the efficacy of certain disinfection and sterilisation methods.
Cleaning can physically remove microbes, but it doesn’t kill them. Importantly, cleaning also won’t break down biofilms - colonies of microbes that encase themselves in a protective film or slime - which are a persistent problem in ICUs.
Cleaning processes use detergents, enzymes, and mechanical action, such as brushing, scrubbing, spraying, and ultrasonic cleaning. This makes removing debris and cleaning crevices and other awkward surface geometry more effective.
The cleaning process results in a reduction of the bioburden (a measurement of the presence of live microorganisms) of 99 to 99.9% or a 2-3 log reduction.
This, along with details of the cleaning agent used, its temperature, how long it came into contact with the device, and any leftover residue, is recorded as evidence of sufficient decontamination.
Level 2: Disinfection – Reducing Microbial Load
This intermediate level of decontamination kills all microbes except bacterial spores, such as Clostridium difficile, which causes antibiotic-associated colitis and other HAIs, and Bacillus cereus, which causes food poisoning.
Chemical disinfectants include alcohol, chlorine, formaldehyde, glutaraldehyde, iodophors, ortho-phthalaldehyde, peracetic acid, phenolics, and quaternary ammonium compounds, while controlled heat exposure assists in eliminating microbe numbers.
The disinfection process destroys most viruses and fungi, resulting in a reduction of the bioburden of 99.9 to 99.999% or a 3-5 log reduction.
The effectiveness of the cleaning is not only tested for the percentage of microbes killed but also the ability to kill specific microbes, such as biofilm-forming bacteria.
To be effective in this area requires specific chemical concentrations, contact times, and temperatures, which are all recorded as part of the validation.
New ultraviolet light technology has emerged, which may assist with the disinfection of endoscopes and other medical devices.
Endoscopes are a particular concern as these are devices that sit in the semi-critical category, yet, according to multiple reports, can remain contaminated with bacterial pathogens after disinfection.
An NHS trial tested the technology on endoscopes in a healthcare environment and found that it significantly shortened decontamination to just 60 seconds. It also removed the need for harsh chemicals, which can cause wear and tear on medical devices over time.
Level 3: Sterilisation – Ensuring Complete Safety
As the highest level of decontamination, sterilisation achieves the greatest bioburden reduction: 99.9999%, or a 6 log reduction. This process kills all microorganisms, including bacterial spores.
Processes include steam sterilisation, or autoclaving, which is considered the most reliable method of sterilisation and the one that can be most broadly applied.
Dry heat sterilisation may be used to sterilise heat-stable devices, while ethylene oxide, a gas-based method, is a popular route for devices that are less able to tolerate heat and moisture as part of the decontamination process. Hydrogen peroxide is also used as a vapour-based form of sterilisation.
Radiation (using gamma rays, electron beams, and X-rays) is another important alternative, which can penetrate complex device structures and operate at lower temperatures, which is important for temperature-sensitive devices.
Understanding the Certificate of Analysis Requirements for Medical Devices
Manufacturers and suppliers of medical-grade materials, components, or devices, as well as those who reprocess medical devices, often need to produce a certificate of analysis (CoA) for their products.
A CoA demonstrates that medical devices and their components meet both decontamination and safety standards. It’s a critical documentation that provides:
- Batch identifiers
- Manufacturer and testing lab identifiers
- Specific testing methods
- Acceptance standards for decontamination and safety
- Test results
- Authorisation from personnel qualified to provide a CoA
This information can be used to certify a device and trace its journey in the event of contamination.
However, it’s important to remember that a CoA does not constitute a legal guarantee of compliance. This is something both the UK government and the FDA agree on.
The UK government states that a CoA is “not evidence that the manufacturer of the device has met the requirements of the UK Medical Device Regulations”, and the US government's FDA states that “you may not rely on your supplier’s CoA to verify the identity of your components.”
However, certain standards can be tested for and included in the CoA to make it a more robust record. Specifically, by meeting the criteria for ISO 13485, a device manufacturer demonstrates their processes (design, development, and production) meet risk identification and mitigation standards. Including evidence of ISO 13485 on a CoA also assists entry into the global marketplace through a recognised standard of compliance.
Sourcing Components that Support Compliance and Reliability
When sourcing components or procuring devices that need to meet strict safety standards, there are three main elements to consider.
A priority should be to vet suppliers based on strong risk management expertise across their entire manufacturing and supply chain operations.
Within this, component selection is key. This needs to be based on rigorous standards, such as their compatibility and long-term durability when faced with the varied decontamination processes.
Finally, traceability and the necessary documentation to support this process are key to ensuring compliance and mitigating risk. A supplier should be able to provide comprehensive technical documentation, including test data to support their products.
These practices are crucial both to patient safety and continued viability in today’s highly regulated healthcare landscape. Read more about checking for hazards in medical devices.
