What is a Process Challenge Device (PCD)?

Health care institutions require the option to monitor the effectiveness of medical device sterilization processes.1 This is vital for providing sterility assurance, as reducing the likelihood of inadequate reprocessing subsequently reduces the risk of using a contaminated medical device. This can ultimately reduce the risk of healthcare associated infections, including surgical site infections, and therefore maximize patient safety.2 In order to assess the effectiveness of sterilization cycle conditions, the use of a PCD alongside a sterilization assurance indicator, typically a biological indicator (BI), is required.1, 3

Monitoring the effectiveness of sterilization

In accordance with the Association for the Advancement of Medical Instrumentation (AAMI), a PCD is used to assess the effectiveness of sterilization processes by providing a defined challenge which is equal to or greater than the most challenging medical device that is routinely reprocessed.1, 3 This challenge is provided by barriers within PCDs which make it difficult for sterilizing agents to fully access the sterilization assurance indicator contained inside, replicating the challenge provided by complex medical devices.1 The sterilization assurance indicator, either a BI or a chemical indicator (CI), demonstrates whether or not conditions are adequate to achieve sterilization.3

BIs are typically selected as sterilization assurance indicators instead of CIs, as they consist of a standardised, viable population of microorganisms, thus closely replicating real-world sterilization practices.1 Whilst a negative BI does not prove that all items in the load are sterile, or that all were exposed to adequate sterilization conditions, they can highlight whether or not the conditions were adequate to achieve sterilization.3 The chosen microorganisms, typically bacterial spores, are known to be resistant to the mode of sterilization used.3 These spores should be of a defined strain, available through a recognized culture collection, and identifiable by appropriate test methods.4

Accuracy, speed and traceability

  • Accuracy: Accuracy is required to provide sterility assurance whilst reducing the number of errors. Errors, such as false positives, can contribute to an increased burden on health care systems; false positives can result in wasted sterilant, delayed instrument turnaround, instrument re-wrapping, unnecessary recalls, increased likelihood of patient notifications and unnecessary antibiotic use.5 Therefore, maintaining accuracy is vital for ensuring efficient use of hospital time and resource.
  • Speed: In accordance with the AAMI standards, a PCD in conjunction with an appropriate BI should be used daily, although preferably in every sterilization cycle.3 This has been suggested as several factors can limit the effectiveness of sterilization cycles, including the condition of the hospital sterilizer equipment and the expertise of the sterilizer operator.3 Owing to the need for frequent testing, alongside the increasing clinical demands placed upon hospitals,6 PCDs and BIs must be rapid to increase the efficiency of a hospital’s central sterile services department.
  • Traceability and compliance: The results from PCDs and BIs must be recorded to support epidemiological tracking alongside the continual assessment of a sterilization cycle’s reliability.3

Advanced Sterilization Products (ASP): benefits of a combined system

To provide an AAMI compliant, streamlined sterility test procedure, ASP developed the STERRAD VELOCITY™ Biological Indicator System/Process Challenge Device, the first combined PCD and BI system for hydrogen peroxide sterilization.5 This system meets the necessary requirements for effective, efficient monitoring of the sterilization of surgical instruments:

  • Accuracy: Working in collaboration with medical device manufacturers, ASP analysed over 15,000 in-use STERRAD™ System cycles to determine the narrow window between the configurations of the most challenging medical device and cycle parameter limits.5 This minimises the room for error during testing and therefore reaffirms the accuracy of monitoring.
  • Speed: The STERRAD VELOCITY™ Biological Indicator System/Process Challenge Device provides results in 15 minutes.* This rapid time to read ensures that sterilization monitoring can keep pace with the increased demand placed upon central sterile services departments.7
  • Reliability and compliance: The intelligent, guided interface of the STERRAD VELOCITY™ Reader system ensures compliance to BI regulatory guidelines and instructions for use. Together with ASP ACCESS™ technology7 cycle outcomes are automatically archived, thus reducing the need for manual record keeping and subsequently the associated workload for central sterile services departments. In the event of a positive BI/PCD result, a complete sterilization record of BI/PCD information is prepared for traceability and compliance purposes.7

*15 minutes or 30 minutes to results, depending on the software version.



  1. Kirckof S. Process challenge devices: validating sterilization. Biomed Instrum Technol 2008;42:309-11.

  2. Güler Y, Erbin A, Gozdas T. An outbreak of postoperative rapidly developing and multidrug-resistant Klebsiella pneumoniae urosepsis due to a contaminated ureteroscope. Folia Med (Plovdiv) 2022;64:401-407.

  3. Association for the Advancement of Medical Instrumentation. ANSI/AAMI ST58:2013/(R)2018 Chemical sterilization and high-level disinfection in health care facilities. 2018. Available from: https://webstore.ansi.org/standards/aami/ansiaamist582013r2018. Accessed 03/02/2023.

  4. International Organization for Standardization. Sterilization of health care products — biological indicators — part 1: general requirements. 2017. Available from: https://www.iso.org/standard/66442.html. Accessed 27/02/2023.

  5. Advanced Sterilization Products. The first and only all-in-one BI and PCD for hydrogen peroxide sterilization that meets AAMI Recommended Practices. Accessed 27/02/2023.

  6. Kumar P and Parthasarathy R. Walking out of the hospital: The continued rise of ambulatory care and how to take advantage of it. 2020. Available from: https://www.mckinsey.com/industries/healthcare/our-insights/walking-out-of-the-hospital-the-continued-rise-of-ambulatory-care-and-how-to-take-advantage-of-it. Accessed 27/02/2023.

  7. Advanced Sterilization Products. STERRAD VELOCITY® Biological Indicator (BI)/Process Challenge Device (PCD): Audit Ready – AAMI Compliant – Streamlined Processing. Accessed 06/03/2023.



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