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CRCST: Sterilization

CRCST · Work through your exam, one topic at a time.

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Sterilization

What this domain tests

Sterilization destroys all microbial life, including spores. The exam tests sterilization methods, cycle parameters, loading, monitoring with physical, chemical, and biological indicators, and what to do when a load fails.

Core rules

  • Match the method to the item and the manufacturer's IFU: steam, ethylene oxide (EO), hydrogen peroxide gas plasma, dry heat, or other validated systems.
  • Steam uses moisture plus heat under pressure. Common cycles are 121°C (250°F) for 30 minutes gravity or 132°C (270°F) for about 4 minutes pre-vacuum; follow the sterilizer IFU and AAMI ST79. Pre-vacuum cycles need a Bowie-Dick test each day they are used.
  • EO is low temperature, with 30-60% relative humidity, 55-60°C, and concentrations commonly 450-1200 mg/L; aeration removes toxic residue. EO suits heat- or moisture-sensitive devices.
  • Hydrogen peroxide plasma is low temperature, leaves no toxic residue, and is limited by lumen size and material compatibility.
  • Load so steam contacts every surface: hinged instruments open, trays not overcrowded, containers level, and no stacking that blocks the chamber.
  • Monitor every load with physical parameters, a chemical indicator, and a biological indicator (BI) according to policy. For steam the BI is Geobacillus stearothermophilus; for EO and dry heat it is Bacillus atrophaeus.
  • Implants are quarantined until the BI is negative. Immediate-use sterilization is for urgent items, not routine cycles, and requires documentation and transport without contamination.

Worked example

A steam BI is positive from a load containing instrument sets. Reasoning: the load is quarantined and recalled; the sterilizer is removed from service; BI placement, load density, and the cycle printout are reviewed; the sterilizer is repaired or recalibrated; three consecutive BI-negative loads, or the facility's validated protocol, are required before returning to service. Items from the positive load are reprocessed from cleaning.

Traps that cost marks

  • Using the wrong BI: a steam BI will not validate EO.
  • Treating a Bowie-Dick pass as proof of sterilization; it only tests air removal.
  • Reading a chemical indicator as a biological result.
  • Overloading the chamber and calling wet packs 'normal.'
  • Releasing implants before the BI result.