SMS Instruments Sterilization Guidelines & Recommendations

Disinfection/Sterilization in Health Care Facilities Influencing Factors:

Cleaning of the object
Organic and inorganic load present
Type and level of microbial contamination
Concentration of and exposure time to disinfectant/sterilant
Nature of the object
Temperature and relative humidity

Sterilizing contaminated instruments is an essential component of an effective infection-control program to protect both patients and health care staff. Reusable medical devices, including surgical instruments that enter normally sterile tissue or the vascular system require sterilization before each use. Improperly sterilized or contaminated medical devices utilized in patient care can contribute to surgical-site infection and pose a serious risk to the patient’s safety and welfare and can result in a serious life-threatening infection or even death.

Guidelines & Recommendations

The following recommended practices for Sterilization were developed by the Association of Perioperative Registered Nurses (AORN) Recommended Practices Committee. These recommended practices are intended as guidelines adaptable to various practice settings.

Patient care items should be processed for reuse based on the intended use of the item.
Devices labeled as single use should not be processed unless the FDA guidelines for reprocessing of singleuse devices can be met.
Items to be sterilized should be cleaned, decontaminated, inspected, packaged, sterilized and stored in a controlled environment.
Items to be sterilized should be inspected for cleanliness and proper function.
Items to be sterilized should be packaged in a manner that promotes successful sterilization.
Saturated steam under pressure should be used to sterilize heat-and-moisture stable items unless otherwise indicated by the device manufacturer.
Immediate use sterilization should be kept to a minimum and should be used only in selected clinical situations in a controlled manner.
Ethylene oxide sterilization is a low temperature process that may be used for moisture- and heat-sensitive surgical items and when indicated by the device manufacturer.
Low-temperature hydrogen peroxide gas plasma sterilization methods should be used to sterilize moisture- and heatsensitive items and when indicated by the device manufacturer.
Low temperature hydrogen peroxide vapor sterilization methods should be used for moisture- and heat sensitive items and when indicated by the device manufacturer.
Sterilization systems using ozone should be used for moisture- and heatsensitive items when indicated by the device manufacturer.
Dry-heat sterilization should be used only for materials that are impenetrable to moist heat. Dry heat may be used to sterilize anhydrous (i.e., waterless) items that can withstand high temperatures and when indicated by the device manufacturer.
Liquid chemical sterilant instrument reprocessing systems that use peracetic acid as a low-temperature sterilant should be used for devices that are heat-sensitive, can be immersed, are approved for this process by the device manufacturer, and cannot be sterilized using terminal sterilization methods.
A formalized program between the healthcare organization and healthcare industry representatives should be established for the receipt and use of loaned instrumentation.
Sterilized materials should be labeled and stored in a manner to ensure sterility and marked with the sterilization date.
Transportation of sterile items should be controlled.
Personnel should receive intial and ongoing education and competency validation for sterilization practices.
Documentation should reflect activities related to sterilization.
Policies and procedures for sterilization and sterilization-related processes and practices should be developed, reviewed periodically, revised as necessary and readily available in the practice setting.
A quality assurance and performance improvement processs should be in place to measure patient, process and system outcome indicators.


Following established protocols, i.e., best practices for instrument reprocessing is an important aspect of modern health care as it helps to minimize the patient’s risk of infection. This article is intended to provide an overview of the six (6) recommended steps for instrument reprocessing; cleaning, inspection, packaging, sterilization, sterile storage, and quality assurance.


The first and most important step in instrument reprocessing is cleaning, as studies [Alfa, 1998] have shown that a dirty instrument cannot be effectively sterilized. This is because the soil shields bacteria and viruses from the sterilizing agent. As a result, bacteria and viruses may very well survive the sterilization process and can cross infect the next patient.

The most common method of cleaning instruments is manual cleaning (cleaning by hand). Manual cleaning has the advantage of flexibility, in that any type of instrument can be cleaned manually. Drawbacks to manual cleaning are that the cleanliness of the instruments can vary between workers as well as that employees are at risk of being exposed to possible cross infection as they are in contact with contaminated instruments. For these reasons, it is important that health care facilities establish protocols for instrument cleaning and require staff to wear proper personal protection equipment (PPE) when working with contaminated instruments.

Recommended procedures for manual cleaning are to first soak the instrument in a tepid or lukewarm water or detergent bath for at least 10 minutes. This step softens and loosens much of the soil that may have dried on the instrument between the time it was used and the time cleaning has started. The duration of the soak depends upon how much soil is on the instruments and how long the soil has been allowed to dry. Note: The use of enzyme detergents is preferred as they help to break up organic soil more readily and rapidly than do conventional detergents. The next step is to completely brush the instrument with a medium-soft bristle brush while it is in the soak bath. In the case of tubed devices like dental handpieces, the insides (lumens, channels, etc.) should be brushed out as well. Care should be taken to use brushes recommended by the manufacturer to avoid damaging the instrument. Note: Brushing should be done under the surface of the water to minimize aerosols and with brush strokes away from the body to avoid exposure to spray from the brush. The instrument should then be rinsed with clean water and, if difficult-to-remove soil remains, another enzyme soak followed by brushing and rinsing should be done.

Ultrasonic Cleaning

For health care facilities that have them, ultrasonic cleaning is a great follow-up to manual cleaning. Although manual cleaning removes most or all of the visible soil from instruments, it may not remove small or microscopic particles that are protected by the texture of a surface or design features like hinges. Ultrasonic cleaners create microscopic bubbles in the solution that collapse when they contact the instrument releasing energy. This energy “kicks” any soil that is in the area off the instrument. This process is called cavitation. The detergent in the ultrasonic bath suspends the soil particles and keeps them from attaching back to the instruments. Ultrasonic cleaning should be done for a duration specified by the instrument, detergent, or ultrasonic bath manufacturer, whichever is longer. Following ultrasonic cleaning, the instruments are rinsed with clean water and dried. Distilled water is preferred to ensure removal of as much detergent as possible but is only essential if the tap water has a high mineral content that could cause spotting. After drying, the instruments may be packaged for sterilization.

Automatic Washers

Practices that need to clean a large quantity of instruments and/or cassettes should consider purchasing automatic cleaning machines. These machines may resemble home dishwashers or be specialized for the specific needs of cleaning complex instruments, e.g., endoscopic instruments. Validated to meet the special needs of cleaning instruments, automatic washers offer a wide range of temperature settings that allow the instruments to be processed at the maximum safe temperature for their use. Higher temperatures speed cleaning and provide some disinfection. Regardless of the automatic washer type used, instruments must be prepared for processing before being placed into a washer, with the extent of preparation depending upon the capabilities of the washer. The actual preparation must be done in accordance with the washer manufacturer’s instructions. For the simplest washers, manual presoaking and sonication remain as necessary reprocessing steps. More sophisticated washers include a presoaking step in the automated process.


Each and every instrument should be inspected for function and cleanliness after cleaning. Any damaged instrument should be replaced and any instrument with visible soil or residual debris should be returned for further cleaning. Never clean a dirty instrument in a clean area unless you have proper PPE. The cleaning action can cross contaminate other instruments and work surfaces. Special Note: Instruments with stiff joints may be a sign of inadequate cleaning.


Sterile packaging, i.e., pouches, wrap, or rigid containers serve to maintain the sterility of processed instruments and allow for aseptic opening at point of use. Packaging should be done in a clean area using FDA-cleared materials such as pouches, wrap, or rigid containers.


Sterilization pouches are commonly used for small, lightweight instruments and should be placed on edge facing the same direction in the sterilizer. This best practice loading technique assists sterilant penetration and facilitates drying. Prior to sealing a sterilization pouch, it is important to include a “multiparameter” chemical indicator and remove excess air. With self-sealing pouches, be sure to fold the adhesive flap on the perforation line and make contact with both the paper and plastic film (ideally 50% each). Some sterilization pouches come printed with both external and internal chemical indicators. This complies with CDC guidelines, providing the supplier has validated the internal indicator as a multiparameter indicator.


Sterilization wrap is commonly used for instrument trays or cassettes. There are many different types and sizes of wraps available. Typically, two sheets are needed to provide an effective barrier and a specific technique is recommended [CDC, AAMI ST79] to allow for aseptic opening. Wrapped instruments should be secured with sterilization tape that also serves as an external indicator. Before closing, a multi-parameter chemical indicator should be included inside along with the instruments. Be sure to select the correct size wrap and be careful not to wrap too tight or too loose as either can compromise sterility by creating air pockets or allowing strike through. Recently, wrap manufacturers have stated not to stack wrapped items during storage as this can compromise sterility.

Rigid Containers

Sterilization containers are commonly used for heavy, mostly layered instrument trays, i.e., orthopedic sets. A maximum weight of 25 pounds has been established [AAMI ST79, AORN] regardless of the instrument trays being wrapped or placed in rigid containers. There are many different types and sizes of rigid containers, all of which provide excellent protection during storage and can be stacked during storage without compromising sterility. For quality assurance, a multiparameter chemical indicator should be included on each layer of multilayered sets and in opposite corners of rigid containers.


Steam sterilization is the most commonly used process for sterilizing instruments, trays, and cassettes. According to the CDC, steam under pressure is the process of choice whenever possible as it is considered safe, fast, and the most cost-effective for health care facilities. Steam sterilizers come in many different sizes and sterilizer cycles can vary among manufacturers. The cycle a sterilizer runs can typically be found in the sterilizer manual. The following are examples of standard cycle parameters (AAMI ST79, AORN) for packaged instruments.

Gravity – 121°C/250°F for 30 minutes exposure and 15–30 minutes drying time
Gravity – 132°C/270°F for 15 minutes exposure and 15–30 minutes drying time
Gravity – 135°C/275°F for 10 minutes exposure and 30 minutes drying time
Dynamic Air Removal – 132°C/270°F for 4 minutes exposure and 20–30 minutes drying time
Dynamic Air Removal – 135°C/275°F for 3 minutes exposure and 16 minutes drying time

Other commercially available sterilization processes include: chemical vapor, dry heat, ethylene oxide, vaporized hydrogen peroxide, and ozone. Although each of these processes offer advantages and disadvantages, the decision about which sterilization process the health care facility should choose lies with the instrument manufacturer as to what was validated in their instructions for use (IFU). For patient safety, the process must be compatible as to not cause damage and must be efficacious to ensure sterility.


Sterilized packages should be stored in a manner that reduces the potential for contamination, i.e., clean, dry, and temperature- and traffic-controlled areas. Sterility is event related and sterile items are considered sterile unless damaged or open. Therefore, it is important for sterilized packages to be handled with care: avoid dragging, crushing, bending, compressing, or puncturing. During transport, they should be protected from environmental contaminants. Prior to use, each sterilized package should be inspected for integrity. If a package is suspect, it should not be used and the item should be reprocessed. Sterile packages should not be opened until point of use.


Sterility assurance of processed instruments should be routinely verified using three (3) types of indicators; physical, chemical, and biological.

Physical Indicators

Physical indicators consist of the time, temperature, and pressure gauges built into sterilizers. For each sterilization cycle, these readings should be observed and verified prior to unloading the sterilizer. Large freestanding sterilizers, which are often found in surgery centers and hospitals, are required to have a chart or printout that is initialed after each cycle. This physical indicator is then maintained as part of their overall infection-control records. Many tabletop sterilizers do not provide physical indicator printouts.

Chemical Indicators

Chemical indicators (CIs) change color or show movement during the sterilizer cycle to verify that some or all sterilization parameters were met. As stated earlier, CIs should be used on the outside and inside of all sterilized packages. CIs range in performance characteristics and health care facilities should select the CI that best fits their monitoring needs. Indicator tape is an example of an external CI and it simply indicates that a package was run in the sterilizer. Internal CIs are used to ensure the sterilant penetrated the packaging system and a Class 5 integrating indicator demonstrates that ALL of the parameters necessary for sterilization were met for that specific cycle.

If using a dynamic air removal (pre-vacuum) sterilizer, an air removal test should be run daily. This is called a Bowie-Dick type test and passes when the chemical indicator sheet inside a process challenge device (PCD) changes to a uniform color after processing at 134°C/274°F for 3.5- or 4-minute exposure time. This test should be ran in an empty sterilizer and drying time is optional as this daily air removal test is performed without a load.

Biological Indicators

Biological Indicator (BI) monitoring is the gold standard for sterility assurance [CDC, 2003, 2008] as BI’s contain bacterial spores that test the lethality of sterilizers. The science behind this is, if your sterilizer can effectively kill the highly resistant spores in the BI, then we can be confident it is capable of killing the less resistant organisms found on our instruments. Biological Indicators are available in both mail-in and in-office systems. BIs should be run at least weekly, per CDC guidelines [CDC, 2003, 2008]. Weekly BI monitoring is completed by running a BI in the sterilizer with a load. In-office BI testing requires test vials, a preset incubator, and a record notebook. After processing, the BI is incubated at a preset.

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