Steps of Steam Sterilization

Step 1: Decontaminate, clean, and dry all instruments and other items to be sterilized.

Step 2: Open or unlock all jointed instruments and other items, such as hemostats and scissors, and disassemble those with sliding or multiple parts. This allows steam to reach all surfaces of the item. Avoid arranging the instruments and other items together tightly, because this prevents steam from reaching all surfaces.

Step 3: If instruments and other items are to be wrapped before steam sterilization, use two layers of paper, newsprint, or cotton or muslin fabric (do not use canvas). Instruments and other items should not be placed in a closed container. If drums are being used, make sure the holes of the drum are open.

Step 4: Arrange all packs, drums, or unwrapped items in the chamber of the autoclave in a way that allows steam to circulate freely.

Step 5: Because there are many types of autoclaves in use around the world, it is difficult to provide guidance on the specific instructions of operating each. Follow the manufacturer's instructions whenever possible. In general, sterilize wrapped items for 30 minutes and unwrapped items for 20 minutes at 121 degrees C (250 degrees F) and 106 kPa (15 lb/in²) pressure. (Do not begin timing until the autoclave reaches the desired temperature and pressure.)

Note: The units of pressure marked on an autoclave's pressure gauge may vary from one autoclave to another. The following amounts of pressure (which are approximately equivalent) are the desired pressure for autoclaving:

15 lb/in² (15 pounds per square inch)
106 kPa (106 kilopascals)
1 atm (1 atmosphere)
1 kgf/cm² (1 kilogram of force per square centimeter)
776 torr
776 mm Hg (776 millimeters of mercury)

Step 6

If the autoclave is automatic, the heat will shut off and the pressure will begin to fall once the sterilization cycle is complete. If the autoclave is not automatic, turn off the heat or remove the autoclave from the heat source after 30 minutes if items are wrapped, 20 minutes if items are unwrapped. Wait until the pressure gauge reads "zero" to open the autoclave. Open the lid or door to allow the remaining steam to escape. Leave instrument packs or items in the autoclave until they dry completely, which could take up to 30 minutes.

Note: Items must be removed dry. Once removed from the autoclave, damp packs draw microorganisms from the environment and should be considered contaminated.

Step 7: Remove the packs, drums, or unwrapped items from the autoclave using sterile pickups. To prevent condensation after removing packs or drums from the autoclave, place them on a surface padded with sterile paper or fabric until they are cool. Wait until the packs, drums, or items reach room temperature (which may take up to several hours) before storing.

Step 8: Store items properly. Proper storage is as important as the sterilization process itself:

Wrapped items. Under optimal storage conditions and with minimal handling, properly wrapped items can be considered sterile as long as they remain intact and dry. For optimal storage, place sterile packs in closed cabinets in areas that are not heavily trafficked, have moderate temperature, and are dry or of low humidity. When in doubt about the sterility of a pack, consider it contaminated and resterilize it.

Unwrapped items. Use unwrapped items immediately after removal from the autoclave or keep them in a covered, sterile container for up to one week.

Autoclave maintenance

If you use steam sterilization at your facility, autoclave maintenance should be part of every sterilization procedure. If the autoclave is faulty, sterilization will not be achieved.

Steam must contact all surfaces. Before sterilization, open or disassemble instruments and other items, pack the autoclave loosely, and use open containers with holes on the bottom or open drums with holes open.

Always sterilize instruments and other items for the correct amount of time at the correct pressure and temperature.

Be sure items are completely dry before removing them from the autoclave.