The Ultimate Guide to Cleaning Verification

Historically, the importance of cleaning instruments effectively has been minimized or, worse yet, forgotten. The belief of assessing a medical device with a simple visual inspection after cleaning was considered efficient enough. However, studies have shown visual inspection to be an insufficient means to determine the cleanliness of instruments and that sterilization processes are ineffective if soil remains on the device. These findings led the Association for the Advancement of Medical Instrumentation (AAMI) to create recommendations for cleaning monitoring, known as cleaning assurance. AAMI is a non-profit organization that serves as the primary source for standards in the medical device industry, most notably, standards that guide cleaning and sterilization in a hospital setting. AAMI/ISO standards ST-79 and ST-91 provide guidelines for cleaning processes and endoscope reprocessing in the clinical setting. The Association of periOperative Registered Nurses (AORN) also provides guidelines for cleaning and sterilization in hospital settings.

This guide will review good cleaning processes, recommended protocols for cleaning assurance, and the products available for use in the clinical setting as part of any cleaning assurance and infection control protocol.

What is cleaning and cleaning assurance?

Cleaning is the first step in reprocessing reusable medical devices. The physical and chemical removal of organic and inorganic materials is the definition of cleaning. However, it does not kill microorganisms, so disinfection and sterilization are necessary to complete the process. Cleaning is not only the first step but an essential part of reprocessing because studies have shown that microbiocidal methods may be ineffective if soil removal is unsuccessful.

Always clean a device in accordance with the item’s instructions for use (IFU). Cleaning begins at the instrument’s point of use and may include mechanical and manual methods of soil removal. Manual cleaning typically starts with a pre-soak, intended to loosen the soil followed by the physical removal of soil by scrubbing instruments.

Mechanical cleaning includes the processing of instruments in an ultrasonic bath, automated endoscope reprocessors (AERs), and washer-disinfectors. Each organization should have written policies and procedures for cleaning reusable medical devices.

Simply put, cleaning assurance is the next logical step in infection control. Ensuring cleaning and sterility for reusable instruments requires monitoring all equipment and processes executed. A test for Cleaning Assurance should be documented, including digital readouts and cycle printouts.

Cleaning Assurance can be broken down into three phases: Validation Testing, Routine Testing, and Verification Testing.

Validation Testing

Complete validation testing at installation, after major repairs, and after routine maintenance. In addition, perform validation testing should have when changing to a new type of cleaning solution or using a new cycle. Validation testing confirms the functionality of the machinery, and these tests are like Bowie-Dick testing for sterilization.

Propper Washer-Disinfector Test Soil

Use the Washer-Disinfector Test Soil to confirm the efficacy of our washer-disinfector at installation, after repair, or after routine maintenance. Test soil is designed to mimic the difficult-to-clean residue that may be left on reusable devices, as described in ISO 15883-5.

Routine Monitoring

Monitor each cycle routinely to ensure that mechanical cleaning equipment works properly, and regular testing allows the user to verify its continued effectiveness. Like chemical indicator monitoring, challenging packs ensure ethylene oxide or steam sterilization.

OK-Sonic™  Ultrasonic Bath Monitor

The OK-Sonic™ Ultrasonic Bath Monitor assesses the effectiveness of your ultrasonic bath cycles. It can help identify issues like poor cavitation, incorrect temperature, or improper detergent use.

It uses dual soil markers to test cleaning efficiency. One soil mark is directly exposed to the bath, while the other is indirectly exposed, simulating both easy and hard-to-clean instruments.

Verification Testing

Verification testing is the final stage of cleaning assurance. It is performed after routine testing to confirm and verify the most difficult-to-clean instruments. It provides the last check before moving on to sterilization. Verification testing is similar to utilizing a test pack containing a biological indicator and an integrator or emulating indicator to challenge the cycle during sterilization for load release.

ProExpose™  Protein Test

ProExpose™ Protein Detection Test quickly verifies that there isn’t any residual protein on reusable devices after cleaning processes and before sterilization or high-level disinfection. ProExpose™ detects protein to a sensitivity of 1.0μg of protein, providing confidence that you are safe to move forward with sterilization.

Propper test soil is simple to use. Before use, add water and the provided ink to the test soil powder to create a paste. Spread the paste throughout the chamber and allow it to dry for 30 minutes. After the soil has dried, run a typical cycle in your washer-disinfector and visually inspect for any remaining residue in the chamber.

WD chex™  Washer-Disinfector Monitor

The WD chex™ Washer-Disinfector Monitor provides a reliable and consistent way to check the performance of washer-disinfectors routinely. It can identify problems like clogged spray arms, overloaded trays, or incorrect detergent levels.

WD chex™ uses dual soil spots to test cleaning efficacy. The monitor holder exposes one soil mark directly to the wash and the other indirectly, mimicking easy and difficult cleaning scenarios.

To use ProExpose™, swab the surface of a difficult-to-clean instrument using the short swab or the cannula of a cannulated instrument using a long swab while they are wet or utilizing sterile water. Place the swab into the vial containing the Coomassie blue solution. If protein is present, the solution will turn blue. The deepness of the blue will vary depending on the amount of protein present on the swab.


Hospitals need to minimize the risk of hospital-acquired infections. Utilizing new technologies in cleaning assurance is a necessary part of this process. Sterilization can only be achieved when instruments have been properly cleaned, which requires verification. As with all new products and tests, hospitals must consider the increased cost, in dollars and in time, when a new process is implemented. Identifying those products and tests with the most manageable transition plan will enable users and purchasers to determine the best product for their institution.

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