Instrument Processing – Sterilization

To date, we have focused on the cleaning process and the importance of ensuring instruments are adequately cleaned and appropriately wrapped or packaged. April’s article ended with loading the sterilizer appropriately.  This month we will discuss the actual instrument sterilization process.

The Sterilization Process

autoclave instrument processing

Sterilization can be defined as the process of making an object free from all living microorganisms. Whenever possible, sterilization of critical and semi-critical instruments should occur before reuse on a patient to reduce the likelihood of disease transmission or infection. There are several options available for instrument sterilization, but the one used most frequently, with dependable results, is steam sterilization.


  • Non-toxic and inexpensive.
  • Cycles are easy to control and monitor.
  • Rapidly microbicidal and short cycle times.
  • Least affected by organic/inorganic soils.
  • Penetrates medical packing, device lumens.


  • Damages heat labile instruments.
  • Not appropriate for heat-sensitive instruments.
  • Moisture-sensitive instruments may dull or rust.
  • Potential for burns.

Using the Steam Sterilizer

In previous articles, the words manufacturer’s instruction for use (IFU) has been penned. Before using any type of device for instrument sterilization ensure that all the manufacturer’s IFU have been read thoroughly and appropriate policies and procedures are in place. Devices have clear instructions on maintenance requirements, preprogrammed cycles as well as instructions on proper loading of contents.

When determining how instruments should be reprocessed it is critical to review the IFU to ensure the correct cycle on the unit is used. In many cases, the selection of a pre-programmed cycle is determined by the type of packaging material, but according to AAMI ST79, there is the possibility that programmed cycles and the cycle parameters recommended in the IFU could differ. If that is the case, then the manufacturer should be contacted to reconcile the difference between the two in order to ensure the instrument is appropriately sterilized prior to use.


“Rationale: Sterilizers and devices vary in design and performance characteristics. The device manufacturer performs the validation for sterilization of its specific device and determines the parameters required for sterilization of that device.”

Once the packages have been appropriately loaded and the process is started, there should not be disruption to the established cycles, such as ending the drying cycle too early in order to remove instruments for use.

Immediate Use Sterilization (Previously FLASH Sterilization)

Instruments should be appropriately wrapped and run through a complete sterilization process. Immediate use of sterilization should only be used in emergency situations and not as a convenience measure. If this process is being used frequently, evaluate the number of instruments available.  There may not be enough on hand to meet patient care demands.

Unloading the Sterilizer

Prior to removing instruments, check the unit for any error messages which may indicate that the indicated parameters for sterilization have not occurred. Depending on the type of unit in use, the manufacturer may recommend opening the door slightly at the end of the cycle. Instrument packages should not be removed from the sterilizer until they are completing dry and cool. Instruments also should not be removed when warm and placed on a cold surface to speed cooling. Once completed cool, the packages may be removed. During the removal process, packages should be inspected for any damage to the integrity of the packaging material, presence of moisture and for visual change of the external indicators. Once evaluated and no issues noted, the packages are ready for appropriate storage and use for patient care.

There are two more articles left in our series. Next month we will review the appropriate monitoring and documentation of the sterilization process. Always remember: if it is documented, it isn’t done.

To find out more about Infection Control Compliance, click here!

ANSI/AAMI ST79 2017. (2017). Arlington Virginia: AAMI, pp.63 – 65
NC SPICE PowerPoint presentation (2019).