Decontamination and Cleaning for the CRCST Exam
Updated October 27, 2026
Cleaning, Decontamination and Disinfection is about a fifth of the CRCST exam. Cleaning is the most important step in reprocessing: if an instrument isn’t clean, it can’t be reliably disinfected or sterilized. Here’s what to know, followed by free practice questions. Questions follow HSPA’s content outline and AAMI standards; at work, each device’s instructions for use (IFU) and your department’s policies come first.
Point of use
- Remove gross soil from instruments right after the procedure.
- Keep instruments moist (for example with an enzymatic spray, foam or a damp towel, as your facility directs) so soil doesn’t dry on.
- Open hinged instruments and separate sharps and delicate items.
- Transport in closed, leak-proof, labeled (biohazard) containers or carts.
The decontamination area
- Wear full PPE: fluid-resistant gown, heavy-duty gloves, face protection (mask and goggles or a face shield), hair cover and shoe covers.
- The area has negative air pressure relative to surrounding areas, so contaminated air doesn’t flow out.
- Traffic flows one way: dirty to clean.
Manual cleaning
- Follow the detergent manufacturer’s dilution, temperature and contact time.
- Clean instruments under the surface of the water to avoid splashing and aerosols.
- Use brushes of the right size for each lumen, and brush lumens thoroughly.
- Rinse well to remove detergent residue.
Mechanical cleaning
| Equipment | How it works | Notes |
|---|---|---|
| Ultrasonic cleaner | Sound waves create tiny bubbles that implode (cavitation) and remove fine soil | Removes soil from hard-to-reach areas; follow the IFU for which items can go in |
| Washer-disinfector | Washes, rinses, thermally disinfects and dries in cycles | Load so water and detergent reach all surfaces |
Free practice questions
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Why must instruments be kept moist after use until they're cleaned?Answer: BBlood and soil that dry on instruments are much harder to remove, which makes cleaning less effective and can protect microorganisms.
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What air pressure does the decontamination area have compared with surrounding areas?Answer: ANegative air pressure keeps contaminated air from flowing out of the decontamination area into clean areas.
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Why are instruments cleaned under the surface of the water during manual cleaning?Answer: CBrushing below the water line reduces splashes and aerosols that could expose staff to contaminants.
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How does an ultrasonic cleaner remove soil?Answer: DUltrasonic cleaners use sound waves to create cavitation, which removes fine soil from crevices and hard-to-reach areas.
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How should contaminated instruments be transported to decontamination?Answer: AClosed, leak-proof, labeled (biohazard) containers protect staff and the environment during transport.
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When using an enzymatic detergent, what should be followed?Answer: BDetergents work as intended only at the manufacturer's specified dilution, water temperature and contact time.
Pass the CRCST exam on your first try
- All 207 questions on decontamination, disinfection, instruments, packaging, sterilization, storage, patient care equipment and professional skills
- An explanation for every answer, with the AAMI standard, CDC guideline or OSHA rule behind it
- Unlimited full 125-question practice exams, with each domain in its real share