Surgical Instrument Care

Staining & Pitting

Surgical instruments are most often made from 300 and 400 series stainless steel, which despite its name can stain and rust and become pitted without proper care.

Liquids of any kind (especially pus, surgical debris, blood and strong chemical solutions) can easily damage your surgical instruments. Allowing any type of liquid or moisture to air-dry on your instruments is to be avoided. Other causes of staining and pitting include cold soaking or washing instruments in solutions such as dish or laundry soap, bleach, iodine solutions, general disinfectants, hand scrub and any solution that contains chlorhexidine or is a chloride-based solution.

Surgical Residues
Blood, pus, and other secretions contain chloride ions which lead to corrosion, most often appearing as dark spots. If blood is left on instruments for 20 minutes or longer they can mark and stain, especially if it’s allowed to dry. Therefore, always clean and dry every instrument thoroughly after use. Remember, an autoclave does not clean; it will only sterilise, so you should only sterilise a clean instrument. The most damaging way to treat surgical instruments is to allow dried-on bodily fluids to become baked-on stains in the autoclave. The high temperature of the autoclave causes chemical reactions that can easily make the stain permanent.

Tap Water
Tap water contains a high concentration of minerals that can be seen as fine cloudy spots on the instrument surface, and can stain an instrument permanently. Rinsing with distilled water is recommended, as is towel drying your instruments immediately and thoroughly and never allowing them to air-dry.

Cleansers
The cleansers and cleaning agents used on instruments could also be a cause of corrosion. Strong substances containing acid or alkaline-based solutions can lead to pitting and staining. Wash instruments with a pH neutral soap (between 7pH – 8pH) that is designed for surgical instruments. Anything with a higher pH may damage the instrument. Never use dish soap, iodine, bleach, cold-soak solution, chlorhexidine-based solutions, laundry soap or hand scrub. Using a cleaning brush is recommended, especially for grooved and serrated instruments.

Rust or Stain?
Stains can be removed, but rust will leave permanent damage. To determine if a brown/orange discoloration is a stain or rust, try rubbing a pencil eraser over the discoloration quite hard. If the discoloration is removed with the eraser and the metal underneath is quite smooth and clean, this is a stain. If a pit mark appears under the discoloration, this is corrosion or rust.

Causes of Staining on Surgical Instruments
Stain Color: Brown/Orange
Most brown/orange stains are not rust. This stain color is the result of high pH surface deposits caused by chlorhexidine usage, improper soaps and detergents, cold-sterilization solution, baked-on blood, soaking in saline or using laundry soap.

Stain Color: Dark Brown/Black
Low pH (< 6) acid stain. May be caused by improper detergents and soaps and/or dried blood.

Stain Color: Blue-Black
Reverse plating may occur when two different types of metals are ultrasonically processed together. For example, stainless steel instruments processed with chrome instruments may cause a stain color reaction. Exposure to saline, blood or potassium chloride will cause this bluish-black stain to occur.

Stain Color: Multi-coloured rainbow effect
Excessive heat caused by a localized hot spot in the autoclave.

Stain Color: Cloudy light spots
Water spots from allowing instruments to air-dry. With slow evaporation, minerals from water are left on the instrument’s surface.

Stain Color: Blue-Grey
Cold sterilization solution being used outside manufacturer guidelines.

Stain Color: Black
Possible exposure to ammonia.