CRCST practice questions

Cleaning, Decontamination & Disinfection: CRCST practice questions and answers

Point-of-use care, manual and mechanical cleaning, water quality, Spaulding levels and chemical disinfection safety. This topic is about 21% of the CRCST exam. Try each question before opening the answer.

1. 1. At the end of a surgical procedure, a scrub person asks how to keep blood from drying on instruments that will not reach decontamination for some time. Which point-of-use action is most appropriate?

   • A. Rinse the instruments thoroughly with sterile saline and leave them to air-dry on the back table
   • B. Wipe off gross soil and keep instruments moist with an enzymatic spray, foam, or a water-moistened towel
   • C. Soak the instruments in a basin of water and a high-level disinfectant until they are transported
   • D. Close all hinged instruments and place them dry in the tray so they are protected during transport
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   B. Wipe off gross soil and keep instruments moist with an enzymatic spray, foam, or a water-moistened towel

   Dried blood and tissue are much harder to remove and can protect microorganisms, so soil should be wiped off and instruments kept moist until cleaning. Saline is a poor choice because its chlorides promote pitting and corrosion of stainless steel. Disinfectants are not used at point of use because cleaning has not yet occurred.

2. 2. A technician is collecting a case cart of contaminated instruments to bring to the decontamination area. Which transport method meets accepted practice?

   • A. Instruments in an open tray covered with a towel so staff can see what is inside
   • B. Instruments in a clean wrapped tray so they look the same as sterile items in the hallway
   • C. Instruments carried by hand in a basin to the nearest pass-through window in the hallway
   • D. Instruments in a closed, leak-proof, puncture-resistant container or cart labeled as biohazardous
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   D. Instruments in a closed, leak-proof, puncture-resistant container or cart labeled as biohazardous

   Contaminated items must be contained so that fluids cannot leak and sharps cannot puncture through, and the container must be marked as biohazardous. An open tray with a towel does not prevent spills or exposure. Disguising contaminated items as clean ones creates a mix-up risk.

3. 3. Which air pressure relationship should the decontamination area have relative to adjacent areas?

   • A. Positive pressure, so air flows out of decontamination into the corridor
   • B. Negative pressure, so air flows into decontamination rather than out of it
   • C. Neutral pressure, so air does not move between decontamination and other areas
   • D. Alternating pressure that switches between positive and negative each hour
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   B. Negative pressure, so air flows into decontamination rather than out of it

   The decontamination area is kept under negative pressure so contaminated aerosols are drawn in and do not escape to clean areas. Positive pressure is used for clean areas such as prep and pack and sterile storage. Neutral or alternating pressure would not contain contaminants.

4. 4. According to the Spaulding classification, a device that enters sterile tissue or the vascular system is classified as:

   • A. Semicritical, requiring high-level disinfection
   • B. Noncritical, requiring low-level disinfection
   • C. Critical, requiring sterilization
   • D. Semicritical, requiring intermediate-level disinfection
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   C. Critical, requiring sterilization

   Spaulding classifies devices by infection risk based on how they contact the body. Items that enter sterile tissue or the bloodstream are critical and must be sterile. Semicritical items contact mucous membranes or non-intact skin and require at least high-level disinfection.

5. 5. When manually cleaning heavily soiled instruments, what water temperature should be used for the initial rinse to remove gross soil?

   • A. Hot water near boiling, because heat loosens blood and kills microorganisms during rinsing
   • B. Any temperature, because rinse temperature has no effect on how well blood is removed
   • C. Hot water, because enzymatic detergents only work above the temperature of steam
   • D. Cool or lukewarm water, because hot water can coagulate proteins and bind them to the surface
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   D. Cool or lukewarm water, because hot water can coagulate proteins and bind them to the surface

   Blood and tissue are protein-based, and hot water causes proteins to coagulate and stick to instrument surfaces, making them harder to remove. Cool or lukewarm water is used for the initial rinse. Enzymatic detergents are damaged by high heat rather than activated by it.

6. 6. Which detergent type is generally most compatible with the widest range of instrument materials and is commonly used for routine manual cleaning?

   • A. Highly alkaline detergent
   • B. Highly acidic detergent
   • C. Abrasive powdered cleanser
   • D. Neutral pH detergent
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   D. Neutral pH detergent

   Neutral pH detergents are gentle on most metals, plastics, and coatings, which makes them a common choice for manual cleaning. Alkaline detergents clean heavy soil and fats well but can damage aluminum and some coatings. Acidic products are used for specific purposes such as removing mineral deposits.

7. 7. ANSI/AAMI ST108 describes two main categories of water used in device processing. What is critical water typically used for?

   • A. Pre-rinsing gross soil from instruments when they first arrive in decontamination
   • B. Filling the hand-washing sinks and eyewash stations in the decontamination area
   • C. The final rinse and other steps where water quality can directly affect the device or patient
   • D. Cleaning the floors and work surfaces in the decontamination area each day
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   C. The final rinse and other steps where water quality can directly affect the device or patient

   Critical water is extensively treated, often by reverse osmosis or deionization, to reduce microorganisms, endotoxins, and minerals, and it is used primarily for the final rinse. Utility water, which is mostly tap water that may need further treatment, is used for flushing, washing, and rinsing steps earlier in the process.

8. 8. How does an ultrasonic cleaner remove soil from instruments?

   • A. High-frequency sound waves create tiny bubbles that implode (cavitation) and dislodge soil from crevices
   • B. High-temperature steam is forced through the instruments to loosen and melt soil
   • C. Rotating spray arms direct high-pressure jets of detergent onto the instruments
   • D. Ultraviolet light breaks down protein soil on the surface of the instruments
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   A. High-frequency sound waves create tiny bubbles that implode (cavitation) and dislodge soil from crevices

   Ultrasonic cleaners use sound energy to cause cavitation, the formation and collapse of tiny bubbles, which removes fine soil from hard-to-reach areas such as serrations and hinges. Spray arms describe a washer-disinfector. Ultrasonic cleaning is a cleaning step, not a disinfection or sterilization step.

9. 9. Why must instruments be thoroughly cleaned before disinfection or sterilization?

   • A. Disinfectants and sterilants only work on instruments that are wet with detergent
   • B. Remaining organic soil can shield microorganisms and reduce the effectiveness of the disinfectant or sterilant
   • C. Cleaning is needed only for appearance, since sterilization kills everything anyway
   • D. Soil causes chemical indicators to change color early and give a false pass
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   B. Remaining organic soil can shield microorganisms and reduce the effectiveness of the disinfectant or sterilant

   Blood, tissue, and biofilm protect microorganisms from contact with the disinfecting or sterilizing agent and can also inactivate chemicals. If an item is not clean, it cannot be reliably disinfected or sterilized. Cleaning is a safety requirement, not just an appearance step.

10. 10. A loaner instrument set arrives from a vendor, and the trays look clean. How should the department process them?

    • A. Sterilize them as received, since the vendor cleaned them before shipping
    • B. Send them straight to the OR, since vendors deliver loaner sets already sterile
    • C. Wipe them with a disinfectant and then send them to sterile storage
    • D. Treat them as contaminated, check the inventory, obtain the IFU, and clean and process them fully before use
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    D. Treat them as contaminated, check the inventory, obtain the IFU, and clean and process them fully before use

    Loaner sets should be considered contaminated on arrival because the department cannot verify how they were handled before they arrived. They must be inventoried, processed according to the manufacturer's IFU, and cleaned, inspected, and sterilized. Visual cleanliness does not confirm the set is safe.

11. 11. A technician receives a flexible endoscope for reprocessing. What step must be done before the endoscope is immersed in cleaning solution?

    • A. Run the endoscope through a steam sterilization cycle
    • B. Soak the endoscope in a high-level disinfectant to make it safe
    • C. Dry all channels with compressed air before the cleaning step
    • D. Perform a leak test as directed by the manufacturer's IFU
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    D. Perform a leak test as directed by the manufacturer's IFU

    A leak test checks for damage to the endoscope's internal channels or outer covering. If a leak exists, immersion can let fluid into the internal parts and cause serious damage, and a damaged scope cannot be reliably reprocessed. High-level disinfection comes after manual cleaning, not before.

12. 12. Why do prions, such as those that cause Creutzfeldt-Jakob disease (CJD), require special processing precautions?

    • A. They are unusually resistant to standard disinfection and sterilization methods
    • B. They multiply rapidly in the decontamination sink if instruments are left wet
    • C. They are destroyed only by ultrasonic cleaning, which most departments lack
    • D. They can be transmitted through the air in the sterile storage area
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    A. They are unusually resistant to standard disinfection and sterilization methods

    Prions are misfolded proteins that resist routine sterilization and disinfection methods, so procedures involving high-risk tissue require special handling defined by facility policy and recognized guidance. They are not living organisms that multiply, and ultrasonic cleaning alone does not destroy them.