Ultrasonic Cleaners for Medical & Surgical Instruments

Medical and surgical instruments in a variety of sizes and complexity can pose challenges when it comes to cleaning, disinfecting and sterilizing them after use.  An ultrasonic cleaner is an ideal tool for the first step in this three step process to protect medical personnel and patients from possible infection due to pathogens that remain on the instruments after a procedure.

The Ultrasonic Principle

Ultrasonic cleaners work on the principle of cavitation whereby ultrasonic transducers create billions of minute air bubbles in an ultrasonic cleaning solution.  These implode with violent force when they come in contact with objects placed in the solution and strip away contaminants without damaging the objects.  When medical and surgical instruments are properly prepared for the ultrasonic cleaning step the process is fast, thorough and efficient.

Pre-prep is important, according to the Association of PeriOperative Registered Nurses (AORN) Recommended Practices Committee, which states that “initial instrument decontamination should begin immediately after any invasive procedure.*” Washing and wiping to remove gross contaminants is important before they dry and more strongly adhere to the instruments.  If instruments are batched before the ultrasonic cleaning step they should be immersed in a sterile solution such as an enzyme soak to further protect against residual contaminants drying on them.  Use brushes to clean the interior of cannulated or lumened instruments.

Throughout the pre-prep and entire process personnel must be careful to avoid cuts and scratches from sharp or pointed instruments.

Ultrasonic cleaners such as the 1.8 gallon capacity Elmasonic S70H and 3.75 gallon capacity Elmasonic S150 available from Tovatech are ideal for cleaning medical and surgical instruments up to 18 inches long.  Both operate at 37 kHz ultrasonic frequency to quickly and safely remove the most stubborn contaminants.  Both offer automatic degassing for fresh cleaning solutions and a sweep function to optimize ultrasonic energy distribution throughout the bath.  Cleaning time can  be programmed on user-friendly operating panels.

A Suggested Ultrasonic Cleaning Procedure

In all cases manufacturers’ instructions should be followed when using an ultrasonic cleaning process. These are representative steps.

Fill the ultrasonic cleaning tank with an approved medical instrument cleaning solution such as CLN-LR012 available from Tovatech following dilution instructions provided.  Turn the cleaner on to start the degassing process.  This step removes entrained air in new solutions that interferes with the efficiency of cavitation and takes approximately 10 minutes.

In the meantime:

  • Segregate instruments by alloy or composition to avoid potential damage
  • Instruments with movable parts should be disassembled to facilitate cleaning
  • Place the instruments the ultrasonic cleaner’s mesh basket, taking care that they do not come in contact with each other
  • Cannulated or lumened instruments should be positioned to insure interiors are wetted with the cleaning solution.  In some instances placing them on an angle will facilitate this
  • Set the control panel per manufacturers’ instructions and start the cleaning process

At the end of the cycle, remove the instruments from the ultrasonic cleaning bath and thoroughly rinse them to remove all traces of the cleaning solution.  Deionized water rinses will avoid spotting. If the instruments are not to be immediately disinfected and sterilized be certain that they are thoroughly dried and protected. Part reassembly can occur after sterilization.

Procedures should be in place to guide the replacement of used ultrasonic cleaning solutions.  In some instances it is recommended that solution be drained and tanks thoroughly cleaned and dried after each ultrasonic cleaning cycle.  Most solutions available today are biodegradable, which facilitates disposal but local authorities should be consulted on proper practices.


What instrument cleaning practices are in use at your healthcare facility?  Are these practices spelled out in the operations manual?

* “Recommended practices for the care and cleaning of surgical instruments and powered equipment” AORN Journal, January 1997

About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world. Read More