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CRCST Sterilization Process practice questions

Steam and low-temperature sterilization methods and cycles, sterilizer testing, loading and unloading, physical, chemical and biological monitoring, process failures, recalls and load documentation. This domain is about 21% of the exam. Try each question, then open the answer.

Read the Sterilization Process study guide

Question 1

A steam sterilizer has just finished a cycle with a full cart of wrapped trays. Which practice best protects the technician from burns while unloading?
  1. Wear heat-resistant gloves and pull the cart out by its handle
  2. Open the door fully and lean in to check the load while the steam clears
  3. Remove each pack by hand right away to check it for moisture
  4. Wear nitrile exam gloves and lift the hot trays straight off the shelves
Show answer

Answer: A. Wear heat-resistant gloves and pull the cart out by its handle

Loads, racks and chamber surfaces are very hot at the end of a cycle. Heat-resistant gloves and moving the load on its cart by the handle keep hands away from hot metal and steam.

Source: HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 14, High-Temperature Sterilization (topic: sterilizer safety and unloading)

Question 2

What does an automated vacuum leak test on a dynamic-air-removal steam sterilizer check?
  1. Whether the incoming steam is at least 97% dry steam
  2. Whether wrapped packs are fully dry at the end of the cycle
  3. Whether air leaks into the chamber while it is under vacuum
  4. Whether bacterial spores are killed during the exposure phase
Show answer

Answer: C. Whether air leaks into the chamber while it is under vacuum

In a leak test the sterilizer pulls a vacuum, holds it, and measures how much the pressure rises. Air leaking in through seals, valves or piping can mix with the steam and keep it from contacting devices. The test is run as often as the manufacturer recommends (some call for daily, some weekly), and a failure means the sterilizer needs service.

Source: ANSI/AAMI ST79:2017/(R)2022, section on air leak testing for dynamic-air-removal sterilizers; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 14, High-Temperature Sterilization

Question 3

When should the Bowie-Dick test be run on a prevacuum steam sterilizer?
  1. Each day, in the last load of the day along with other packs
  2. Once a week, in a chamber that is fully loaded
  3. Daily, in an empty chamber, in the first cycle after warm-up
  4. Only after a biological indicator has come back positive
Show answer

Answer: C. Daily, in an empty chamber, in the first cycle after warm-up

The Bowie-Dick test (a dynamic air removal test) checks that air is removed and steam penetrates quickly. AAMI ST79 calls for it each day the sterilizer is used, in an empty chamber, before the first processed load. It runs after a warm-up cycle so the chamber is at temperature. A failed test takes the sterilizer out of use until the cause is fixed.

Source: ANSI/AAMI ST79:2017/(R)2022, section on Bowie-Dick testing of dynamic-air-removal sterilizers; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

Question 4

According to AAMI ST79, how often should a steam sterilizer be routinely monitored with a BI process challenge device (PCD)?
  1. At least weekly, and preferably daily, per cycle type
  2. Only on days when the Bowie-Dick test has failed
  3. Only after the sterilizer has been repaired or moved
  4. Once a month, in the first load of each month
Show answer

Answer: A. At least weekly, and preferably daily, per cycle type

ST79 recommends routine BI monitoring at least weekly, and preferably every day the sterilizer is used, for each type of cycle run. Every load that contains an implant is also monitored with a BI PCD. BIs are the only monitors that directly show whether spores were killed.

Source: ANSI/AAMI ST79:2017/(R)2022, section on routine biological monitoring of steam sterilizers; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

Question 5

After incubation, a processed steam BI shows no growth, and the unprocessed control BI from the same lot also shows no growth. How should this be interpreted?
  1. The sterilizer failed, so all loads since the last BI must be recalled
  2. The test is invalid; it must be repeated and the cause investigated
  3. The control result does not matter if the processed BI is negative
  4. The load passed because both BIs show no growth
Show answer

Answer: B. The test is invalid; it must be repeated and the cause investigated

A control BI is expected to grow. If it does not, the spores, the media or the incubator may be faulty, so the negative result on the processed BI means nothing. The test is repeated with a good lot and a working incubator, and the event is documented and investigated.

Source: ANSI/AAMI ST79:2017/(R)2022, section on biological indicators (topic: control BIs and interpreting results); HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

Question 6

Which type of steam is best for steam sterilization?
  1. Saturated steam that is at least 97% dry
  2. Steam mixed with some air so the heat spreads evenly
  3. Wet steam with a dryness of about 85%
  4. Superheated steam that is hotter than its pressure calls for
Show answer

Answer: A. Saturated steam that is at least 97% dry

Saturated steam holds the most heat it can at a given pressure without extra liquid water. Steam that is 97% or more dry releases its latent heat when it condenses on cooler surfaces, which kills microorganisms quickly. Wet, superheated or air-mixed steam all reduce effectiveness.

Source: HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 14, High-Temperature Sterilization (topic: steam quality)

Question 7

In a gravity-displacement steam sterilizer at 250 F (121 C), what is the typical minimum exposure time for a wrapped instrument set, per AAMI ST79 tables?
  1. 4 minutes
  2. 10 minutes
  3. 15 minutes
  4. 30 minutes
Show answer

Answer: D. 30 minutes

At 250 F (121 C) in a gravity cycle, wrapped instruments typically need 30 minutes of exposure, plus drying time. The lower temperature and passive air removal mean a long exposure. Always follow the device and packaging IFU, which may require more.

Source: ANSI/AAMI ST79:2017/(R)2022, section on minimum cycle times for steam sterilization; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 14, High-Temperature Sterilization

Question 8

Why must items sterilized with ethylene oxide go through aeration before use?
  1. To cool the items down after a high-temperature cycle
  2. To dry condensate that forms during steam exposure
  3. To remove EO residues that are toxic to patients and staff
  4. To wait until the biological indicator result is read
Show answer

Answer: C. To remove EO residues that are toxic to patients and staff

Plastics, rubber and other materials absorb EO during the cycle. Aeration passes warm, filtered air over the load so the gas leaves before anyone handles the items or they touch a patient. Aeration time and temperature come from the IFU, often about 12 hours at 50 C.

Source: ANSI/AAMI ST41:2008/(R)2018 (now superseded by ST58:2024), section on aeration; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 15, Low-Temperature Sterilization

Question 9

A technician is packaging a heat-sensitive device for hydrogen peroxide gas plasma sterilization. Which packaging should NOT be used?
  1. Polypropylene sterilization wrap
  2. A standard paper-plastic peel pouch
  3. A rigid container validated for the system
  4. A Tyvek-type (spunbonded polyolefin) pouch
Show answer

Answer: B. A standard paper-plastic peel pouch

Paper, linen and other cellulose materials absorb hydrogen peroxide, which can cancel the cycle or leave too little sterilant to reach the device. Packaging for these systems is non-cellulose, such as Tyvek-type pouches and polypropylene wrap. Always check both the sterilizer and packaging IFUs.

Source: HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 15, Low-Temperature Sterilization (topic: hydrogen peroxide packaging)

Question 10

An outpatient clinic processes a heat-sensitive rigid scope in a peracetic acid liquid chemical sterilant system. How should the scope be handled after the cycle?
  1. Wrapped and placed in sterile storage for later use
  2. Aerated for 12 hours before it is used on a patient
  3. Used right away, since it is wet and unpackaged
  4. Placed in a peel pouch and labeled with a load number
Show answer

Answer: C. Used right away, since it is wet and unpackaged

Liquid chemical sterilant systems process items unwrapped and finish with a rinse, so the device comes out wet. It cannot stay sterile in storage, so it is carried in the system's tray to the point of use and used immediately. This is often called just-in-time processing.

Source: ANSI/AAMI ST58:2024, section on liquid chemical sterilant processing systems; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 15, Low-Temperature Sterilization

Question 11

Where should a BI PCD be placed for routine monitoring in a full steam sterilizer load, unless the sterilizer manufacturer says otherwise?
  1. On the top shelf, near the back, close to the steam inlet
  2. On the cart outside the chamber, as the unexposed control
  3. Inside the largest instrument tray on the middle shelf
  4. On the bottom shelf, near the front, over the drain
Show answer

Answer: D. On the bottom shelf, near the front, over the drain

The area above the drain at the bottom front of the chamber is where air and condensate collect. That makes it the hardest spot for steam to reach. Placing the PCD there makes it the toughest challenge in the load.

Source: ANSI/AAMI ST79:2017/(R)2022, section on routine biological monitoring (topic: PCD placement); HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

Question 12

At the start of the shift, a technician finds that the steam BI incubator's display reads far below the temperature the BI manufacturer's IFU requires. Several BIs from last night's loads are incubating in it. What should the technician do?
  1. Report it, take the incubator out of use, and repeat the BI tests
  2. Read the BIs at the usual time and record the results as normal
  3. Note the reading in the log and keep using it until its next PM
  4. Move the BIs to room temperature until the incubator is repaired
Show answer

Answer: A. Report it, take the incubator out of use, and repeat the BI tests

Incubator temperature is checked and recorded because the test organism grows only in a narrow range. Too cool an incubator can hide surviving spores, so a negative result from it cannot be trusted. The incubator is reported and removed from use, and the supervisor decides how to handle the affected loads. The BI tests are repeated in a working incubator.

Source: HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing (topic: incubator checks); BI manufacturer's IFU

Question 13

A gravity-displacement sterilizer printout for wrapped instrument sets reads: "Gravity 270 F; exposure 10:00 at 270.5 to 271.5 F; dry 30:00; cycle complete." The sets' IFU calls for the standard gravity cycle at that temperature. What is the best action?
  1. Release it, since 10 minutes is the gravity exposure time at 270 F
  2. Release only the trays whose internal indicators changed color
  3. Hold the load, since it needed 15 minutes, and reprocess it
  4. Release it, since the printout shows the cycle completed
Show answer

Answer: C. Hold the load, since it needed 15 minutes, and reprocess it

Wrapped instruments in a gravity cycle at 270 F (132 C) typically need 15 minutes of exposure. A 10-minute exposure did not meet the required parameters, so the load is treated as non-sterile and reprocessed. The wrong cycle selection is reported so the cause can be corrected.

Source: ANSI/AAMI ST79:2017/(R)2022, section on physical monitoring and minimum cycle times for steam sterilization; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

Question 14

A trauma surgeon urgently needs an implant set sterilized an hour ago, and its BI result is not yet available. Policy allows early release in a documented emergency. What must be in place?
  1. A Type 1 indicator on the outside of the tray, with verbal approval
  2. A PCD with a BI and Type 5 integrator, an exception form, and follow-up
  3. A passed Bowie-Dick from that morning, with the cycle printout attached
  4. The cycle printout alone, as long as the load has fully cooled
Show answer

Answer: B. A PCD with a BI and Type 5 integrator, an exception form, and follow-up

Early release of an implant is an exception, not routine. The load must be monitored with a PCD holding a BI and a Type 5 integrating indicator. The release is documented on an exception form. The BI is still read and its result followed up.

Source: ANSI/AAMI ST79:2017/(R)2022, section on monitoring and release of implant loads (topic: early release in emergencies); HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

Question 15

After the cooling period, a technician finds water droplets inside the wrap of an instrument tray. What should be done with the tray?
  1. Let it sit on the cart until it is dry, then release it
  2. Wipe the outside of the wrap dry and send it to storage
  3. Release it if the internal chemical indicator changed color
  4. Consider it contaminated and send it back to be reprocessed
Show answer

Answer: D. Consider it contaminated and send it back to be reprocessed

Moisture can carry microorganisms through the wrap, so a wet pack is considered non-sterile. The tray is reprocessed, and the cause (load configuration, set weight, steam quality, drying time or cooling conditions) is investigated and documented.

Source: ANSI/AAMI ST79:2017/(R)2022, section on wet packs; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 14, High-Temperature Sterilization

Question 16

A routine steam BI from this morning turns positive, and the control BI grew as expected. What is the best first response?
  1. Remove the sterilizer from service and notify the supervisor right away
  2. Assume it is a false positive because the printout and indicators passed
  3. Keep using the sterilizer and recheck it with another BI next week
  4. Discard the result and record only a repeat BI that reads negative
Show answer

Answer: A. Remove the sterilizer from service and notify the supervisor right away

A positive BI means the cycle may not have killed all the spores. The sterilizer is taken out of service, and the supervisor and infection prevention are notified. Affected loads are identified and quarantined or recalled per policy. The cause is investigated, the sterilizer retested, and everything documented.

Source: ANSI/AAMI ST79:2017/(R)2022, section on positive BI results and recall; HSPA Sterile Processing Technical Manual, 9th ed. (2023), Ch. 17, Monitoring and Record Keeping for Sterile Processing

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