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Instrument Preparation and Sterilization

All instruments and other equipment used to perform surgery must be sterilized prior to use. This page provides information on how to prepare instruments for sterilization and surgery.

Instrument Preparation

Prior to surgery, instruments and other supplies that require sterilization are cleaned and wrapped or packaged to facilitate handling.

Types of Instrument Packs

  • Instruments, with or without an instrument tray, may be packed inside a folded cloth or paper wrap and sealed with autoclave tape for steam sterilization. A sterilization indicator is placed inside the pack. 
  • Alternatively, instruments may be packed in a self sealing sterilization envelope. Sometimes referred to as 'peel packs', these may be used for steam or gas sterilization. A sterilization indicator is located on the outside of the envelope.

What to Include (in the pack)

Surgical instruments and other sterile material intended to be used during the procedure should be included within the surgical pack. This may include wound clips and applicators, gauze or cotton-tipped swabs and draping material. If pre-packaged (sterile) suture material or other equipment is used this may be aseptically placed onto the open surgical pack prior to the start of surgery.

Keeping the Instruments Sterile During Surgery

Place the opened surgery pack to one side of the surgery field so that the surgeon's arms do not cross over the surgery field to reach the pack. An extra piece of sterile drape material or the inside of the sterile pack wrap can be used as a place to set instruments on when they are not in use. One of the most common errors for an inexperienced surgeon is setting instruments down on an unsterile surface. In addition, sterile suture material must not be allowed to drag over unsterile areas during use.

Sterilization Methods

Surgical instruments and other material or equipment that will contact the surgical site must be sterilized prior to use. In general, investigators are expected to sterilize instruments via autoclave (steam sterilization). Other methods of instrument sterilization [e.g., ethylene oxide (gas) sterilization, chemical (cold) sterilization and dry heat sterilization (glass bead sterilizers)] are occasionally used under specific circumstances.

Steam Sterilization

Steam or autoclave sterilization is the most common method of instrument sterilization. Instruments are placed in a pack and exposed to steam under pressure. A sterilization indicator (required) such as autoclave tape or an indicator strip is used to identify which instrument packs have been sterilized.

autoclave tape


Ethylene Oxide

Ethylene oxide is a chemical that in gaseous form may be used to sterilize items that cannot withstand the high temperature and/or moisture produced in an autoclave. Because ethylene oxide is toxic to humans and other animals, items sterilized with it must be aerated before use to allow the gas to dissipate. Sterilization indicators are also required to identify instrument packs after sterilization. Most peel packs have a built-in indicator for both steam and gas sterilization.

Glass Bead Sterilizers

Glass bead sterilizers have a central well filled with glass beads which are maintained at high temperature (approximately 500 degrees F). Glass bead sterilizers may be used to sterilize instrument tips between rodents when using a single pack for multiple animals. Instruments must be initially sterilized by steam or Glass bead sterilizergas.

The tips of surgical instruments are placed into the hot glass beads for approximately 5-10 seconds. Blood and tissue should be removed from the instrument tips using alcohol or sterile water prior to placement in the glass bead sterilizer. Only the tips of the instruments are sterilized using this method. The instrument tips become extremely hot and must be cooled before use.

One set of surgical instruments may be used on up to five rodents during the same surgical session if the instrument tips are sterilized between each animal using a glass bead sterilizer.

Reusing Instruments

When surgical procedures are to be performed on multiple rodents, the same set of instruments may be used on more than one animal under the following conditions.

  • The instruments must be initially sterilized by autoclaving or gas sterilization.
  • Instrument tips should be cleaned with alcohol or sterile water to remove blood and tissue particles between animals.
  • The tips of instruments must be placed in a hot bead sterilizer between animals.
  • A new set of sterile instruments should be used after every 4-5 animals.
  • If the instruments have become contaminated by contact with a non-sterile surface or non-sterile portions of the body (such as contents of the gastrointestinal tract) a new sterile set of instruments should be used on subsequent animals.

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