Instrument Preparation and Sterilization

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

Types of Instrument Packs

• Instruments, with or without an instrument tray, may be packed inside a folded cloth wrap and sealed with autoclave tape for steam sterilization. A sterilization indicator is placed inside the pack.
• Instruments may be packed in a self sealing envelope with one side made of clear plastic. Referred to as peel packs, these may be used for steam or gas sterilization. The sterilization indicator is part of the package.

What to Include (in the pack)

All surgical instruments and other sterile material that may be needed during the procedure should be included within the surgical pack. This may include suture material and/or needles, gauze or cotton-tipped swabs and draping material. If packaged, presterilized 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

Use an extra piece of sterile drape material or the inside of the wrap 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.

Sterilization Methods

Surgical instruments and other material or equipment that will contact the surgical site must be sterilized prior to use. Methods of instrument sterilization include steam sterilization (autoclave), ethylene oxide (gas) sterilization, chemical (cold) sterilization and dry heat sterilization (glass bead sterilizers).

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 other indicator strip is used to clearly identify instruments that have been sterilized.

Ethylene Oxide

Ethylene oxide gas may be used to sterilize items that may not be exposed to high temperature and or steam. Ethylene oxide is highly toxic. Items sterilized with ethylene oxide must be aerated before use to allow the toxic gas to dissipate. A sterilization indicator (required) is used to clearly identify instruments that have been sterilized. 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 a very high temperature (approximately 500 degrees F). Glass bead sterilizers may be used to resterilize instrument tips between animals when reusing instruments. Instruments must be initially sterilized by autoclaving or gas sterilization.

The tips of surgical instruments are placed into the hot glass beads for approximately 2-5 seconds. Only the tips of the instruments are resterilized using this method. The tips of instruments become extremely hot and must be cooled before they are used.

Glass bead sterilizers may be used between animals when one set of instruments is used on a group of up to 5 animals. Only under special circumstances may glass bead sterilization be used as the sole method of sterilization (must be discussed with the veterinarian).

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.
• Instruments should be wiped with alcohol or sterile saline to remove blood and tissue particles between animals.
• The tips of instruments may 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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