Challenge Accepted: 4 Must-Know PCD Questions for Sterile Processing

When you think of process challenge devices (PCDs), what comes to mind? The most well-known reference PCD is the AAMI 16 towel challenge pack for large steam sterilizers. Of course, that was introduced in the late 1980’s, and technologies have evolved significantly since then.

Today, sterile processing departments (SPDs) have more product choices and sterility assurance responsibilities than ever before, so it’s important they understand how current standards and guidelines impact modern solutions.

A recently published whitepaper in Zentralsterilization, “Process challenge devices in medical device sterilization – the standards and guidelines explained,” covers the basics of PCDs according to industry standards.

Below are questions we think every hospital and healthcare facility with a sterile processing department should be able to answer.

1. What exactly is a PCD?

Process challenge devices have a formal definition in international standards. A PCD is an “item providing a defined resistance to a cleaning, disinfection, or sterilization process and used to assess performance of the process.” (ISO 11139)

Modern device designs will have two main elements: a barrier system and indicator(s):

• Barrier: the PCD itself is intended to create a physical barrier that restricts the access of the sterilization process to the indicator during routine processing. It is intended to mimic the effect of placement of the indicator inside one of the sterilization load’s packages or medical devices.
  
• Indicator(s): the biological and/or chemical indicators should be appropriate for testing the specific sterilization process that will be monitored.

Why should you care?

The term PCD can refer to many different products and solutions, so it’s important you know what type(s) of PCDs your facility uses and understand whether you’re adhering to current industry best practices, not just basic standards.

Did you know?

Solventum’s latest PCDs for steam sterilization and vaporized hydrogen peroxide sterilization feature a contemporary lumen barrier design.

2. What are PCD performance requirements, according to industry standards?

International standards for both steam sterilization (ISO 17665 [6]) and vaporized hydrogen peroxide (VH2O2) sterilization (ISO 22441 [7]) state that PCDs need to be validated for use, and that PCDs for VH2O2 sterilization must simulate worst-case conditions for each cycle type. Importantly, however, international standards do not provide PCD design nor applicable performance requirements for healthcare facilities.

Why should you care?

Not all PCDs are created equally. Accountability is on SPD teams to ensure they are selecting PCDs based on merit to match the needs of their equipment, their facility policies and procedures, and the operational goals of their SPD.

If your facility is using PCDs, make sure you understand the technical aspects of both the PCDs themselves, as well as the sterilizer equipment for which they are validated. Confirm the criteria matches what your facility requires.

Did you know?

Only Solventum indicators (included inside Solventum PCDs) are backed by BSI Kitemark™ certification, proof our products meet rigorous third-party testing and ISO standards, and validated for compatibility with most sterilizer cycles, brands, and models. In 2025, Solventum launched a first-of-its-kind PCD for VH2O2 sterilization, in an effort to raise the bar for what constitutes a best-in-class challenge device.

3. What are the recommended uses of PCDs, according to industry standards?

First, according to international standards (ISO 11138-7 [9]), PCDs are designed so that the placement of the biological indicator within the PCD constitutes a location that is deemed to represent a suitably stringent challenge to the process. In other words, facilities may benefit from using PCDs that contain BIs within them, versus using standalone BIs.

Why should you care?

If your facility uses standalone BIs for routine monitoring, it may be difficult to ensure they are placed in the optimal location for each load. Do all team members across all shifts adhere to the same, consistent processes?

Additionally, international standards (ISO 17665 [6]) for steam sterilization define effective sterilization process verification as being inclusive of confirmed recorded data from physical sensors, chemical indicators, and biological indicators and/or PCDs. In other words, to make sure the sterilization process worked correctly, SPD teams should check three things after the completion of a cycle:

• Confirm physical sensor variables (e.g. temperature, pressure, time) stayed within the required limits.
• Confirm chemical indicators changed color confirming exposure to proper sterilization conditions.
• Confirm lethality of the sterilization cycle using PCDs or standalone biological indicators.

Did you know?

Solventum’s latest PCDs were designed for simplicity and consistency. Solventum’s PCD placement guidance is straightforward, and industry-leading chemical indicators (CIs) are included in every PCD:

• Our steam PCDs are placed in the most challenging area of the sterilizer chamber (typically bottom shelf over drain), foil side facing up or down, with nothing placed directly on top of them
• Our VH2O2 PCDs are placed on the top rack or shelf in the sterilizer chamber, towards the front of the chamber door, as the final item placed in the load.
• All of our latest PCDs contain a Type 5 chemical integrator (steam) or Type 4 Tri-Metric chemical indicator (VH2O2) in addition to a super-rapid biological indicator, making it easier than ever to adhere to stringent safety protocols.

4. How often should PCDs be used, according to industry standards?

Steam sterilization 

In the United States, standards (AAMI ST79 [2]) recommend a BI PCD be used at least weekly and preferably daily for steam sterilization load monitoring.

Why should you care?

Do you know how often your facility is using a PCD to monitor steam sterilization loads? If you’re not monitoring every load with a PCD, you may not technically be violating standards, but are you comfortable knowing some cases and patients could be at greater risk, since you haven’t explicitly monitored the lethality of each cycle with a PCD containing a BI?

Vaporized hydrogen peroxide (VH2O2) sterilization

In the United States, standards (AAMI ST58 [10]) recommend BIs within PCDs (or an FDA-cleared BI-containing quality monitoring device) be used for vaporized hydrogen peroxide (VH2O2) sterilization monitoring for each cycle type every day the sterilizer is in use, but preferably in every load, and for every load containing implants that have been cleared for low temperature sterilization. In other words, facilities should preferably be monitoring every non-implant load, as well as every applicable implant load, with a BI.

Why should you care?

Using PCDs containing a BI (and in our case, a Type 4 Tri-Metric chemical indicator as well) for low-temperature, VH2O2 sterilization is an effective way to maintain quality and compliance.

In fact, we strongly recommend you monitor every VH2O2 load with a PCD.

Please note: Recommendations, insights, and opinions in this article reflect Solventum’s perspective, based on our marketing team’s interpretation of the referenced published paper.