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CRCST Cleaning, Decontamination and Disinfection practice questions

Bloodborne pathogen safety, microbiology and PPE, manual and mechanical cleaning, water quality, cleaning-equipment testing and maintenance, and the Spaulding levels of disinfection. This domain is about 21% of the exam. Try each question, then open the answer.

Read the Cleaning, Decontamination and Disinfection study guide

Question 1

A newly hired technician will work in the decontamination area. Under the federal Bloodborne Pathogens Standard, what must the employer do about hepatitis B vaccination?
  1. Have the employee pay and then submit the cost for reimbursement
  2. Require the vaccine with no option for the employee to decline
  3. Offer the vaccine only after an exposure incident has occurred
  4. Offer the vaccine series at no cost to the employee
Show answer

Answer: D. Offer the vaccine series at no cost to the employee

The Bloodborne Pathogens Standard requires employers to offer the hepatitis B vaccine series to workers with occupational exposure, at no cost to the worker. An employee who declines signs a declination statement and can still accept the vaccine later at no cost.

Source: OSHA Bloodborne Pathogens Standard, 29 CFR 1910.1030(f)(2), hepatitis B vaccination; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 6, Regulations and Standards

Question 2

Offering hepatitis B vaccine to sterile processing staff breaks the chain of infection at which link?
  1. Susceptible host
  2. Reservoir
  3. Portal of exit
  4. Mode of transmission
Show answer

Answer: A. Susceptible host

The chain of infection has six links: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host. Vaccination protects the worker, so the worker is no longer a susceptible host for that virus. Breaking any one link stops the spread of infection.

Source: HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 4, Microbiology for Sterile Processing Technicians (topic: chain of infection)

Question 3

A sterilized device can still cause a fever reaction in a patient if it carries endotoxin. Where does endotoxin come from?
  1. The cell walls of gram-negative bacteria
  2. The protective coat of bacterial spores
  3. The outer envelope of viruses such as HIV
  4. The cell walls of fungi such as Candida
Show answer

Answer: A. The cell walls of gram-negative bacteria

Endotoxin is a lipopolysaccharide in the outer membrane of gram-negative bacteria. It is released when the bacteria die and it is heat-stable, so ordinary sterilization does not destroy it. Prompt cleaning and good water quality keep bacterial loads, and therefore endotoxin, low before sterilization.

Source: HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 4, Microbiology for Sterile Processing Technicians; ANSI/AAMI ST108:2023, section on water quality (endotoxin)

Question 4

Which ensemble is correct for a technician doing manual cleaning at a decontamination sink?
  1. Cloth lab coat, exam gloves tucked under the coat cuffs, surgical mask, hair cover, and shoe covers
  2. Fluid-resistant gown, heavy-duty gloves, hair cover, shoe covers, with eye protection only at the ultrasonic
  3. Scrub top, heavy-duty gloves, safety glasses without side shields, hair cover
  4. Fluid-resistant long-sleeved gown, heavy-duty gloves over gown cuffs, mask with face shield, hair and shoe covers
Show answer

Answer: D. Fluid-resistant long-sleeved gown, heavy-duty gloves over gown cuffs, mask with face shield, hair and shoe covers

Manual cleaning creates splashes and aerosols, so decontamination attire must protect skin, eyes, nose, and mouth. That means a fluid-resistant gown with sleeves and heavy-duty gloves whose cuffs extend over the gown cuffs. Add a fluid-resistant mask with eye protection (goggles or a full-length face shield). Finish with a hair cover, and shoe covers or dedicated shoes. The employer provides this PPE.

Source: ANSI/AAMI ST79:2017/(R)2022, section on personal protective equipment in decontamination; OSHA Bloodborne Pathogens Standard, 29 CFR 1910.1030(d)(3), personal protective equipment

Question 5

A technician is splashed in the eyes with detergent solution while cleaning instruments. How long should the eyes be flushed at the eyewash station?
  1. About 1 minute
  2. At least 15 minutes
  3. About 5 minutes
  4. Until the stinging stops
Show answer

Answer: B. At least 15 minutes

Eyewash stations meeting ANSI/ISEA Z358.1 deliver a flushing flow for at least 15 minutes, the usual minimum for a chemical splash. The product's SDS first-aid section may call for longer. Plumbed units are activated weekly to confirm they work.

Source: ANSI/ISEA Z358.1-2014 (R2020), emergency eyewash equipment; OSHA 29 CFR 1910.151(c); OSHA Hazard Communication Standard, 29 CFR 1910.1200(g)(2)(iv), safety data sheet first-aid measures

Question 6

A technician doubles the amount of enzymatic detergent in the sink because the instruments look especially bloody. What is the most likely result?
  1. Faster protein breakdown, so the soak time can be cut in half
  2. A solution strong enough to also disinfect the instruments
  3. No change at all, because enzymes cannot be overconcentrated
  4. More residue to rinse off, with no proven gain in cleaning
Show answer

Answer: D. More residue to rinse off, with no proven gain in cleaning

Detergents are tested and labeled at a specific dilution, water temperature, and contact time. Using more than the label calls for does not improve cleaning and leaves more residue to rinse off. Residues can harm devices or patients.

Source: ANSI/AAMI ST79:2017/(R)2022, section on cleaning agents; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 8, Cleaning (topic: detergents)

Question 7

An automated endoscope reprocessor (AER) finishes its cycle, but the printout shows a channel-flow alarm. What should the technician do with the endoscope?
  1. Treat it as not disinfected, correct the cause, and reprocess it
  2. Release it, since the cycle ran all the way to completion
  3. Wipe the outside with alcohol and release it
  4. Release it and record the alarm in the AER log
Show answer

Answer: A. Treat it as not disinfected, correct the cause, and reprocess it

A channel-flow alarm means solution may not have reached every channel, so high-level disinfection cannot be assumed. The technician checks the connectors and channels for blockage or misconnection, then reprocesses the scope per its IFU. The alarm and the corrective action are documented.

Source: ANSI/AAMI ST91:2021, section on automated endoscope reprocessors; ANSI/AAMI ST58:2024, section on high-level disinfection; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 8, Cleaning

Question 8

During the daily check of a washer-disinfector, what should a technician confirm about the spray arms?
  1. They spin freely and their nozzles are not clogged
  2. They are oiled with instrument lubricant before the first cycle
  3. They are locked in place for even coverage
  4. They are removed so trays fit more easily
Show answer

Answer: A. They spin freely and their nozzles are not clogged

Spray arms deliver water and detergent to every part of the load, so they must turn freely and have open nozzles. Debris, mineral buildup, or an item sticking up from a tray can block or stop an arm. Checking them daily per the washer's IFU catches problems before loads come out dirty.

Source: ANSI/AAMI ST79:2017/(R)2022, section on care and maintenance of mechanical cleaning equipment; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 8, Cleaning (topic: mechanical cleaning equipment)

Question 9

A technician is loading a washer-disinfector rack with a general surgery set. Which practice is correct?
  1. Close ratchets on the first tooth to keep instruments in place
  2. Stack trays closely so more fit in each cycle
  3. Cover the rack with a towel to hold small items in place
  4. Open hinged instruments and leave room for the spray
Show answer

Answer: D. Open hinged instruments and leave room for the spray

Washer-disinfectors clean by spraying water and detergent onto every surface. Hinged instruments are opened so box locks and jaws are exposed, and racks are not overloaded so the spray reaches everything. Items are placed as the washer and device IFUs direct.

Source: ANSI/AAMI ST79:2017/(R)2022, section on mechanical cleaning (loading); HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 8, Cleaning

Question 10

Which item should usually be kept out of a standard ultrasonic cleaner?
  1. A stainless steel needle holder with serrated jaws
  2. A set of stainless steel Army-Navy retractors
  3. A stainless steel hemostat after manual pre-cleaning
  4. A rigid telescope with optical lenses
Show answer

Answer: D. A rigid telescope with optical lenses

Ultrasonic cleaning is meant for stainless steel instruments with crevices, hinges and serrations. The vibration can damage the lenses of rigid telescopes and the seals around them, so most telescope IFUs do not allow it. Check each device's IFU before placing it in the ultrasonic.

Source: Rigid endoscope manufacturers' IFUs; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 8, Cleaning (topic: ultrasonic cleaning)

Question 11

Within a day of cataract surgery, several patients at an eye surgery center develop sterile, non-infectious inflammation in the front of the eye. Which problem does this pattern suggest?
  1. Endophthalmitis caused by a sterilization failure
  2. Creutzfeldt-Jakob disease spread by instruments
  3. A latex allergy to the surgeon's gloves
  4. Toxic anterior segment syndrome (TASS)
Show answer

Answer: D. Toxic anterior segment syndrome (TASS)

TASS is an acute, sterile inflammation of the front (anterior segment) of the eye that usually appears within a day or two of surgery. It is a toxic reaction to something that entered the eye during surgery, not an infection, so antibiotics do not prevent it.

Source: ASCRS/ASORN Recommended Practices for Cleaning and Sterilizing Intraocular Surgical Instruments; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 8, Cleaning

Question 12

A neurosurgery case is scheduled for a patient with suspected Creutzfeldt-Jakob disease. What should sterile processing staff expect to do with the instruments?
  1. Process them routinely, since standard steam cycles destroy prions
  2. Use immediate-use steam sterilization so they are processed quickly
  3. Follow the facility's prion policy and keep them moist
  4. Let them dry before transport to reduce the aerosol risk
Show answer

Answer: C. Follow the facility's prion policy and keep them moist

Prions resist routine processing, so facilities keep a written CJD/prion policy developed with infection prevention. It often calls for single-use items where possible and special cleaning and sterilization protocols for high-risk tissue. Instruments are kept moist and not allowed to dry, since dried prion-contaminated soil is very hard to remove. SPD should be told about the case in advance so it can prepare.

Source: CDC Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, updated June 2024), discussion of prions; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 4, Microbiology for Sterile Processing Technicians (topic: prions)

Question 13

When should a flexible endoscope's leak test be done in the reprocessing sequence?
  1. After high-level disinfection, just before it goes into storage
  2. Only when the scope shows visible damage
  3. After manual cleaning, just before it goes into the AER
  4. After pre-cleaning and before immersion in cleaning solution
Show answer

Answer: D. After pre-cleaning and before immersion in cleaning solution

A leak test checks that the scope's outer covering and internal channels are intact. It is done after every use, after pre-cleaning and before the scope is immersed in cleaning solution. That way a damaged scope does not take in fluid.

Source: ANSI/AAMI ST91:2021, section on leak testing; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 11, Complex Surgical Instruments

Question 14

A reusable laryngoscope blade contacts mucous membranes. What is the minimum level of processing it needs after cleaning?
  1. Sterilization, because it enters the body
  2. Intermediate-level disinfection
  3. High-level disinfection
  4. Low-level disinfection
Show answer

Answer: C. High-level disinfection

Under the Spaulding classification, items that touch mucous membranes or non-intact skin are semi-critical and need at least high-level disinfection after cleaning. Sterilization is acceptable for them but goes beyond the minimum.

Source: CDC Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, updated June 2024), A Rational Approach to Disinfection and Sterilization; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 9, Disinfection

Question 15

How often should a reusable ortho-phthalaldehyde (OPA) solution be checked with minimum effective concentration (MEC) test strips?
  1. Once a week, on a set day
  2. Only when the solution looks cloudy
  3. Only on the day the solution is first poured
  4. Before each use, as the product IFU directs
Show answer

Answer: D. Before each use, as the product IFU directs

Reusable high-level disinfectants are diluted by water carried in on devices and lose strength over time. MEC test strips confirm the solution is still at or above its minimum effective concentration. They are used before each use per the IFU. Results are documented each time.

Source: ANSI/AAMI ST58:2024, section on monitoring high-level disinfectant concentration; CDC Guideline for Disinfection and Sterilization in Healthcare Facilities (2008, updated June 2024), Chemical Disinfectants (ortho-phthalaldehyde); HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 9, Disinfection

Question 16

Before a manual high-level disinfection cycle, the MEC test strip shows the glutaraldehyde solution has failed. What should the technician do?
  1. Add fresh concentrate to the basin to bring it back up to full strength
  2. Use it, but double the immersion time to compensate
  3. Discard it, refill with fresh solution, retest, and document
  4. Use it for today's scopes and change it tomorrow
Show answer

Answer: C. Discard it, refill with fresh solution, retest, and document

A failed MEC test means the solution can no longer be relied on to achieve high-level disinfection. It is discarded, replaced with fresh solution prepared per IFU, retested, and the failure and corrective action are documented. No devices are processed in the failed solution.

Source: ANSI/AAMI ST58:2024, section on monitoring high-level disinfectant concentration; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 9, Disinfection

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