CRCST practice questions

Sterilization Process: CRCST practice questions and answers

Steam cycles and air removal, loading, biological and chemical indicators, IUSS and low-temperature methods. This topic is about 21% of the CRCST exam. Try each question before opening the answer.

1. 1. Which combination of factors must all be achieved for steam sterilization to be effective?

   • A. High pressure, high humidity, and a long drying phase
   • B. Temperature, chemical concentration, and aeration time
   • C. Time, temperature, saturated steam, and direct steam contact with all surfaces
   • D. Pressure, a vacuum hold, and cool-down on a solid surface
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   C. Time, temperature, saturated steam, and direct steam contact with all surfaces

   Steam sterilization depends on the right temperature held for the right time, delivered by saturated steam that directly contacts every surface. Pressure is only the means of raising the steam temperature; it does not kill microorganisms by itself.

2. 2. A load of wrapped instrument sets is processed in a prevacuum steam sterilizer. Which exposure parameters are a standard minimum for this cycle type?

   • A. 270°F (132°C) for 4 minutes
   • B. 250°F (121°C) for 4 minutes
   • C. 270°F (132°C) for 1 minute
   • D. 230°F (110°C) for 30 minutes
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   A. 270°F (132°C) for 4 minutes

   A dynamic air-removal (prevacuum) cycle at 270°F (132°C) for 4 minutes is the standard minimum exposure for wrapped instruments. A 250°F cycle needs a much longer exposure time, and 1 minute at 270°F is far too short for wrapped sets.

3. 3. At the end of a cycle, a technician finds visible moisture on the outside of a wrapped tray. What should be done with the tray?

   • A. Let it dry on the cart, then release it to sterile storage
   • B. Consider it non-sterile, reprocess it, and investigate the cause
   • C. Wipe the moisture off and release it if the indicator passed
   • D. Release it only for use in the same day's cases
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   B. Consider it non-sterile, reprocess it, and investigate the cause

   A wet pack is considered contaminated because moisture can wick microorganisms through the packaging. It must be repackaged and resterilized, and the cause should be looked into; a passing chemical indicator does not make a wet pack acceptable.

4. 4. A technician is loading a sterilizer with several empty basins. How should the basins be positioned?

   • A. Upright, with the open side facing up to hold steam
   • B. Upside down and stacked flat on the shelf
   • C. Tilted on edge, all facing the same direction so condensate drains
   • D. Nested tightly together with no separation
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   C. Tilted on edge, all facing the same direction so condensate drains

   Basins and other concave items are tilted so air can escape and condensate can drain out instead of pooling. An upright basin collects water, and tightly nested basins trap air and moisture; nested basins need absorbent separation and the same orientation.

5. 5. Before removing packages from a steam sterilizer after a cycle, what should the operator review first?

   • A. The biological indicator result from the next morning
   • B. The date on the sterilizer's last preventive maintenance sticker
   • C. The physical monitor printout or display to confirm cycle parameters were met
   • D. The color of the external tape on one package
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   C. The physical monitor printout or display to confirm cycle parameters were met

   Physical monitors (printout or electronic record) show whether time, temperature, and pressure were met for that specific cycle. The operator verifies and signs or initials this record; external tape only shows that a package went through a process.

6. 6. A Bowie-Dick test is used to check which aspect of sterilizer performance?

   • A. Air removal and steam penetration in dynamic air-removal sterilizers
   • B. The number of spores killed during a gravity cycle
   • C. Ethylene oxide gas concentration during exposure
   • D. The accuracy of the sterilizer's drying time
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   A. Air removal and steam penetration in dynamic air-removal sterilizers

   The Bowie-Dick (air-removal) test detects air leaks, inadequate air removal, and noncondensable gases in dynamic air-removal sterilizers. It does not measure microbial kill, which is what a biological indicator does.

7. 7. Which microorganism is used in biological indicators for monitoring steam sterilization?

   • A. Bacillus atrophaeus
   • B. Clostridium difficile
   • C. Geobacillus stearothermophilus
   • D. Mycobacterium tuberculosis
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   C. Geobacillus stearothermophilus

   Geobacillus stearothermophilus spores are highly resistant to moist heat, making them the standard challenge for steam BIs. Bacillus atrophaeus is used for ethylene oxide and dry heat.

8. 8. A steam load contains an orthopedic implant. According to standard practice, when can the implant be released for use?

   • A. After the biological indicator in that load's process challenge device shows a negative result
   • B. As soon as the physical monitor printout is reviewed
   • C. When the external chemical indicator changes color
   • D. After the load has cooled for at least 30 minutes
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   A. After the biological indicator in that load's process challenge device shows a negative result

   Every load containing an implant should be monitored with a BI in a PCD, and the implant should be quarantined until the BI result is known. Physical monitors and chemical indicators alone are not enough to release implants in routine practice.

9. 9. A positive BI triggers a recall. Which loads are generally included in the recall?

   • A. Only the single tray that contained the BI PCD
   • B. Only loads processed on the same day as the failed BI
   • C. All loads processed in that sterilizer since the last negative BI result
   • D. Only items that have not yet left the department
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   C. All loads processed in that sterilizer since the last negative BI result

   Since there is no evidence the sterilizer worked correctly after the last negative BI, items from those loads are considered suspect. Load records and lot numbers make it possible to identify and retrieve them; limiting the recall to one tray could miss non-sterile items.

10. 10. Which chemical indicator class reacts to all critical variables of a sterilization process and is designed to correlate with the performance of a biological indicator?

    • A. Class 3, a single-variable indicator
    • B. Class 4, a multi-variable indicator
    • C. Class 5, an integrating indicator
    • D. Class 1, a process indicator
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    C. Class 5, an integrating indicator

    Class 5 integrating indicators respond to all critical variables and are tested to perform comparably to a BI. Class 4 indicators react to two or more variables but are not designed to match BI performance.

11. 11. What is the role of immediate-use steam sterilization (IUSS)?

    • A. To save time on routine cases when trays are short
    • B. To process items needed urgently for patient care when there is no time for terminal processing
    • C. To sterilize implants as a routine practice
    • D. To replace cleaning when an instrument is needed quickly
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    B. To process items needed urgently for patient care when there is no time for terminal processing

    IUSS is meant for urgent situations, such as a dropped instrument with no replacement, and is not a substitute for adequate instrument inventory. Items must still be fully cleaned and decontaminated first, and implants should not be routinely processed this way.

12. 12. What does a sterility assurance level (SAL) of 10^-6 mean?

    • A. One million microorganisms remain on each item after processing
    • B. The cycle kills microorganisms in one-millionth of a second
    • C. Six spore strips must be tested in every load
    • D. There is no more than a one-in-a-million chance that a viable microorganism remains on an item
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    D. There is no more than a one-in-a-million chance that a viable microorganism remains on an item

    An SAL of 10^-6 is the probability standard for terminal sterilization of medical devices: at most a one-in-a-million chance of a surviving microorganism. It is a statistical measure, not a count of survivors or a testing requirement.