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Manual and Mechanical Cleaning (CRCST Domain 2: Cleaning, Decontamination and Disinfection)

AI fact-checked, not reviewed by a certified technician. Spot an error? Report it. Report an error Outline refs: Sec2 II, Sec2 III, Sec2 V.H.

TL;DR
  • Cleaning is the most important step: items that are not clean cannot be reliably disinfected or sterilized. [CDC 2008 guideline; HSPA outline Sec2]
  • Brush items below the water surface to prevent aerosols. [AAMI ST79 (verify section)]
  • Ultrasonic cleaners remove fine soil by cavitation. [HSPA outline Sec2 III]
  • Mechanical cleaning equipment is tested with cleaning verification tools; frequency follows AAMI guidance and the IFU. [ANSI/AAMI ST79:2017 §13.2 (summarized in HPN Online, 2022)]

Cleaning removes soil and most of the microbial load (bioburden) from a device. It is the foundation of everything that follows: disinfectants and sterilants cannot reach microorganisms hidden under blood, tissue or biofilm. If an item is not clean, it is not ready for the next step.

Manual cleaning

Manual cleaning is used for devices that cannot go in a mechanical washer, and as a pre-clean for complex items. Use the detergent the IFU specifies at the correct dilution and temperature. Very hot water is avoided for the first rinse because it can coagulate proteins and make them stick. Brush instruments below the surface of the water so you do not create contaminated aerosols. Select brushes that match the lumen diameter and length in the IFU, and disassemble devices that are designed to come apart.

Ultrasonic cleaning

An ultrasonic cleaner sends high-frequency sound waves through the solution. These create tiny bubbles that collapse (implode) against the device surface, a process called cavitation, which dislodges fine soil from hinges, serrations and crevices. Ultrasonic cleaning does not replace gross soil removal and is not a disinfection or sterilization process.

Washer-disinfectors

Automated washer-disinfectors combine pre-rinse, detergent wash, rinses, a thermal or chemical disinfection phase and drying. Loading matters: open instruments, do not overload racks, and position items so spray can reach every surface. Operators check spray arms and nozzles daily so water reaches all surfaces. If a cycle aborts or alarms, the load is treated as not cleaned and reprocessed.

Verifying cleaning

Cleaning verification tests (test soils or indicators) challenge the washer to show it is removing soil. They do not prove sterility. ANSI/AAMI ST79:2017 recommends testing mechanical cleaning equipment upon installation, each day it is used, and after major repairs, and documenting the results. (Older editions said weekly, preferably daily.) Follow the equipment IFU as well.

How the CRCST tests this

Expect questions on why brushing is done under water, how ultrasonic cleaners work, what washer verification tests prove, and what to do with a load after a washer malfunction.

Practice questions

Q1 · D2 · Sec2 V.H · AI fact-checked · Report an error

How does an ultrasonic cleaner remove soil from instruments?

A. High-frequency heat that boils soil off the instrument surfaces
B. Cavitation: tiny bubbles that form and implode, dislodging soil
C. Strong water jets from rotating spray arms that blast soil off
D. Enzymes activated by sound waves that dissolve all organic soil

Answer: B

Ultrasonic cleaners use sound waves to create cavitation, the formation and collapse of microscopic bubbles. This dislodges fine soil from crevices and box locks. It is a cleaning step, not disinfection or sterilization.
ES: La limpieza ultrasónica usa ondas de sonido que generan cavitación: burbujas microscópicas que se forman e implosionan y desprenden suciedad de grietas y articulaciones. Es limpieza, no desinfección ni esterilización.
Q2 · D2 · Sec2 V.E · AI fact-checked · Report an error

During manual cleaning in the sink, why should instruments be brushed below the surface of the water?

A. To keep the detergent at working temperature
B. To prevent the creation of contaminated aerosols
C. To let enzymes reach hinges and serrations
D. To protect the brush bristles from drying out

Answer: B

Brushing above the waterline throws contaminated droplets and aerosols into the air, exposing staff. Keeping the item submerged while brushing contains the spray.
ES: Cepillar fuera del agua lanza gotas y aerosoles contaminados al aire y expone al personal. Mantener el artículo sumergido al cepillar contiene la salpicadura.
Q3 · D2 · Sec2 II.A · AI fact-checked · Report an error

How should a cleaning brush be selected for a lumened instrument?

A. Skip brushing if the lumen is flushed with enzymatic detergent under pressure
B. Use the same brush for all lumens to keep technique consistent across sets
C. Match the brush diameter and length to the lumen as specified in the IFU
D. Use any reusable brush, as long as it is disinfected at the end of the day

Answer: C

A brush that is too small does not contact the lumen walls; one too large may not pass or may cause damage. Follow the IFU.
ES: Un cepillo muy pequeño no toca las paredes del lumen y uno muy grande puede no pasar o dañarlo. Siga las IFU.
Q4 · D2 · Sec2 III.A · AI fact-checked · Report an error

Cleaning verification tests for a washer-disinfector are used to:

A. Measure only whether the thermal rinse reached disinfection temperature
B. Prove that items leaving the washer are sterile and ready for use
C. Check the detergent concentration in the dosing line each shift
D. Confirm that the cycle effectively removes soil

Answer: D

Cleaning indicators or test soils challenge the washer to show it is cleaning properly. They do not prove sterility.
ES: Los indicadores de limpieza demuestran que la lavadora limpia correctamente. No prueban esterilidad.
Q5 · D2 · Sec2 V.H · AI fact-checked · Report an error

When loading a washer-disinfector, instruments should be:

A. Closed and stacked tightly so more items fit into each washer cycle
B. Placed in closed containers so small parts are not lost
C. Placed with heavy items on the top rack to protect light items
D. Opened, not overloaded, and positioned so spray can reach all surfaces

Answer: D

Proper load configuration lets water and detergent contact every surface.
ES: Una configuración correcta permite que el agua y el detergente toquen todas las superficies.

Common mistakes

Resumen en español: La limpieza es el paso más importante: sin limpieza no hay desinfección ni esterilización confiables. Cepilla bajo el agua para evitar aerosoles, usa el cepillo del tamaño indicado en las IFU y evita agua muy caliente en el primer enjuague. El ultrasonido limpia por cavitación, pero no desinfecta. En la lavadora-desinfectadora, carga correctamente, revisa brazos aspersores y, si el ciclo falla, reprocesa la carga. Las pruebas de verificación de limpieza no prueban esterilidad.

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Related topics

FAQ

What is cavitation?

The formation and implosion of tiny bubbles caused by ultrasonic energy, which knocks soil off device surfaces.

Does a passing washer cleaning test mean the items are sterile?

No. It shows the washer cleans effectively. Sterility comes later from a validated sterilization process.