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What kind of terminal processing step should be in place after cleaning?

FDA’s guidance on reprocessing re-usable medical devices[1] indicates that in addition to reprocessing instructions that allow for thorough cleaning, an appropriate microbicidal process should be in place. Which terminal processing step should be included will depend on the device’s potential for transmitting infections on the one hand, and on what kind of treatment the device can withstand on the other.

Re-usable devices are categorized into one of three categories depending on their risk of transmitting infections: critical devices, semi-critical devices, or non-critical devices1. These categories have different requirements in terms of terminal processing as is outlined below:

Critical devices

Critical devices are defined as devices that are introduced directly into the bloodstream or contact a normally sterile tissue or body space1,[2]. As such, these devices have a high potential for the transmission of infection when contaminated and should therefore be sterilized after cleaning. The method of choice for sterilization is steam since this is the most widely used method in health care settings. Steam is dependable, non-toxic, and relatively inexpensive. Hence, if the device can withstand it, a steam sterilization procedure should be used. If the device cannot withstand steam (e.g. heat-labile devices), low temperature sterilization technologies exist such as H2O2 sterilization, O3 sterilization, EO sterilization and liquid chemical sterilization. In exceptional cases, a high-level disinfection (chemical or thermal) procedure can be implemented as the terminal processing step. However, choosing high-level disinfection as a terminal processing step over sterilization will need to be thoroughly justified.

Semi-critical devices

Semi-critical devices are defined as devices that will contact intact mucous membranes or non-intact skin, but ordinarily do not penetrate tissues or otherwise sterile areas of the body1,2. The same recommendations apply for these devices as for critical devices, but whereas high-level disinfection methods need to be thoroughly justified for critical devices, they are deemed appropriate for semi-critical devices when the device design does not permit sterilization.

Non-critical devices

Non-critical devices are devices that will either contact intact skin but do not penetrate it, or which have no direct patient contact but may become cross-contaminated in a clinical setting1,2. Here, the terminal process required will depend on the extent of the patient and healthcare personnel contact, as well as the nature and extent of contamination. To determine which terminal processing step is required, a risk-based approach should be applied considering the clinical use and the type of soil.

Non-critical devices that come in direct contact with patients or healthcare personnel and that are soiled with blood or other potentially infectious materials should be intermediate-level disinfected after cleaning2. On the other hand, non-critical devices that do not come in direct contact with patients or healthcare personnel but are soiled with blood or other potentially infectious materials should at a minimum be low-level disinfected after cleaning2. Finally, non-critical devices that are not expected to be soiled by blood or other potentially infectious materials should be, at a minimum, visibly clean2.

Other considerations

As indicated in our topic on thermal disinfection, having an automated thermal disinfection procedure in place is recommended as a final processing step or to prepare a device for safe handling whenever possible. Additionally, the user base of your devices should always be kept in mind. For instance, if you have a semi-critical device that can withstand sterilization, but which will be sold to users that do not have access to steam sterilization, having a high-level disinfection procedure in addition to a steam sterilization procedure may be useful.

In conclusion

The recommended terminal processing step will depend on the device classification and the processing the device can withstand. Critical devices must be sterilized after cleaning. Steam sterilization is recommended, and it may be useful to keep this in mind when designing the device. Semi-critical devices should at least be high-level disinfected but are recommended to be sterilized as well. For non-critical devices, the required terminal processing step will depend on the level of patient and healthcare personnel contact as well as the nature and extent of the contamination. For all of these devices, a risk-based approach should be applied to determine the required terminal processing step.


[1] Food and Drug Administration, 2015 “Reprocessing Medical Devices in Health Care Settings: Validation Methods and Labeling”

[2] AAMI TIR12:2020 “Designing, testing, and labeling medical devices intended for processing by health care facilities: A guide for device manufacturers”