Benefits of Cleaning Verification for Medical Devices

What is cleaning verification?

Residual protein soil on medical instrument

Cleaning verification helps confirm if residual protein is still present on a tested medical device after a completed cleaning process. Protein is found in blood, body tissue, mucous, organs and virtually everywhere in the human body. It is the most common procedural soil found on instruments, not to mention the most difficult to remove.⁵

If not removed during the cleaning process, residual protein may provide a challenge to the sterilization process that can result in the transfer of microorganisms between patients.

So how does a sterile processing (SPD) manager, GI Manager, or Technician verify that the cleaning process from bedside to assembly has been successful? A cleaning verification program can help add assurance.

Here are three primary benefits of including cleaning verification as part of your process:

Meets recommendations of ANSI/AAMI ST79
Becomes an important step in your quality management process
Reduces risk of cross contamination between patients

What do the standards say about cleaning verification?

SPD manager conducting cleaning verification.

To ensure cleaning is being done effectively on medical devices, facilities should develop a defined program that includes identifying instrument types and frequency for testing.

Your device processing cycle likely already employs a basic cleaning verification program: visual inspection. However visual inspection alone is not enough, even with the use of lighted magnification or borescopes. There may still be soil that can be missed.

Let’s look at what ANSI/AAMI standards say about cleaning verification and visual inspection for sterile processing:

"Visual inspection alone may not be sufficient for assessing the efficacy of cleaning processes; the use of methods that are able to measure organic residues that are not detectable using visual inspection should be considered in facility cleaning policy and procedures" (ANSI/AAMI ST79 and ST91)^1,2

Cleaning verification by users should include (a) visual inspection combined with other verification methods that allow the assessment of both external surfaces and inner housing and channels of medical devices, (b) testing the cleaning efficacy of equipment, and (c) monitoring key cleaning parameters. (ANSI/AAMI ST79)¹

When selecting a cleaning verification product beyond visual inspection, Annex D of ANSI/AAMI ST79 outlines recommendations¹ that the test be:

Rapid
Easy to perform
Sensitive (meeting realistic benchmarks)
Accurate

Repeatable
Free of interfering substances
Robust (does not require exacting conditions or time constraints that cannot be achieved routinely)

What types of cleaning verification tests are available?

Numerous cleaning verification tests are available for healthcare applications. These processes test for a variety of residual soil types including protein, adenosine triphosphate (ATP), hemoglobin, and carbohydrates. Of these, the two most common are protein and ATP cleaning verification systems.

Test	What is Detected	Benefits	Potential Drawbacks
Protein Detection i.e. VERIFY RESI-TEST SWAB or SLIDE-THRU Cleaning Indicators	Protein and proteinaceous substances (such as coagulated blood)	Clinically relevant, organic soil Found in most surgical and therapeutic procedures Most difficult soil to clean using today’s neutral and enzymatic detergents Nationally recognized benchmark level of <6.4 μg/cm2 (1,2) Color change provides a semi-quantitative result and failures are determined by facility policy*	Protein may be insoluble in water requiring physical removal to collect samples Denaturing from thermal or chemical processes can affect detection levels
ATP	Adenosine Triphosphate	ATP is present in living cells including human, bacterial, and fungal Automated read provides a numerical result Numerical result can be trended over time or used for comparison between technicians*	Not clinically relevant, organic soil Requires specialized reader ATP degrades rapidly rendering undetectable over time, even when soil remains Threshold values vary between manufacturers Studies demonstrate ATP did not show failing results despite presence of blood and protein³ FDA cautions against reliance on ATP test for duodenoscope cleaning⁴

* Always follow the OEM device and healthcare manufacturer's IFU in conjunction with your facility policy.

What test is best for your application?

Protein can be hiding. Many facilities may be aware of ATP testing, but unfortunately it does not specifically detect protein, blood, or carbohydrates.

Instead, ATP testing detects cells and bacteria suspended within these materials. It is important to note it is only detecting the ATP from the metabolic activity of the cells contained, or suspended, in those items, and only if there are enough cells present to yield a detectable amount of ATP. If that metabolic activity is not present, then the test will demonstrate passing results even if soils are present.

Protein tests are quick, accurate, and easy to use. They are performed on a medical device and require no additional machines or equipment for interpretation. More importantly, peace of mind and standard of care must be considered. Unlike ATP, which loses its detectability over time, protein remains constant because protein is present on the device, even if it cannot be seen, until it is removed.⁶

Explore VERIFY RESI-TEST Cleaning Indicators

VERIFY RESI-TEST Cleaning Indicators are available in both SWAB and SLIDE-THRU options:

VERIFY RESI-TEST SWAB Cleaning Indicators are used to test surfaces and ports with easy-to-read results available in just five seconds.
VERIFY RESI-TEST SLIDE-TRU Cleaning Indicators slides through the internal channels and lumens, making it ideal for endoscopes. The slide through brush once extracted from the scope is then dipped into the test tube and a visible color change after just ten seconds provides test results.

Article References

1 ANSI/AAMI ST79:2017 Comprehensive guide to steam sterilization and sterility assurance in health care facilities

2 ANSI/AAMI ST91:2021 Flexible and semi-rigid endoscope processing in health care facilities

3 AJIC American Journal of Infection Control, Vol. 45, Issue 6, S7-S8 Evaluation of Reprocessing Effectiveness for Flexible Ureteroscopes, June 2017

4 U.S. Food & Drug Administration Safety Communication; https://www.fda.gov/medical-devices/safety-communications/fda-recommending-transition-duodenoscopes-innovative-designs-enhance-safety-fda-safety-communication accessed 12/01/2020

5 AJIC American Journal of Infection Control, Vol. 41, pp. 245-248 Worst-case soiling levels for patient-used flexible endoscopes before and after cleaning. October 1999

6 Chemistry Library – LibreTexts: https://chem.libretexts.org/Bookshelves/Biological_Chemistry/Supplemental_Modules_(Biological_Chemistry)/Metabolism/ATP_ADP