When a Steam Sterilizer Load Changes: A Practical Change-Control Framework

Steam sterilization is not determined by the sterilizer cycle alone. Successful processing also depends on cleaning, device preparation, packaging, loading, sterilant delivery, monitoring, and the suitability of the cycle for the load contents [1]. For this reason, a change to a routine load should be treated as a controlled process change rather than simply as an operator preference.

Examples include adding a new instrument set, increasing the number of trays, changing from wrapped sets to containers, changing pouch orientation, combining previously separate load categories, or changing the position of a difficult-to-process item. The objective is not to prohibit operational flexibility. It is to ensure that flexibility remains within a documented and evidence-supported operating range.

Why load configuration matters

Steam must contact accessible surfaces and displace air from the chamber, packaging, trays, lumens, and other challenging spaces. Overcrowding, excessive density, poor orientation, contact with the chamber wall, or obstructed drainage may interfere with steam circulation, air removal, penetration, or drying [1][2]. A load may therefore meet programmed cycle settings while presenting a different practical challenge from the load that was originally evaluated.

CDC guidance identifies loading the sterilizer and the appropriateness of the cycle for the load contents as elements of the overall sterilization process. It also recommends additional biological and chemical indicator testing when major changes are made to packaging, wraps, or load configuration [1].

What should trigger a formal review?

Facilities should define their own change-control threshold. A review is prudent when a proposed change affects one or more of the following:

• Mass or density: heavier trays, greater metal mass, tightly packed instruments, or a configuration that may affect drying.
• Geometry: long, narrow, hollow, hinged, nested, or otherwise difficult-to-process devices.
• Packaging: a new wrap, container, filter, pouch, configuration, or packaging density.
• Load arrangement: a different shelf, rack, basket, orientation, spacing, or position for items considered more challenging to process.
• Load composition: combining items that were previously processed separately or introducing materials with different heat, moisture, or drainage characteristics.
• Equipment or process conditions: sterilizer relocation, major repair, cycle redesign, software change, or a change in the intended use of the cycle.

These categories are practical change-control considerations. They should not be read as a universal regulatory checklist or as evidence that every listed change independently makes a load unacceptable. The facility should determine, using documented rationale, whether existing evidence applies or whether further evaluation is necessary.

A practical five-step evaluation process

1. Describe the change precisely

A statement such as “new tray added” is difficult to evaluate. Record the affected device or set, packaging system, approximate mass or dimensions where relevant, intended cycle, proposed quantity, loading position, and reason for the change. Include photographs or a loading diagram when position and orientation are important.

Identify whether the change is temporary or permanent. A one-time emergency load and a new routine configuration may require different controls, but both should be clearly identified and documented.

2. Compare the proposed load with the established load

Compare the new configuration with a previously accepted configuration using meaningful characteristics rather than appearance alone. Consider total mass, density, surface area, packaging materials, instrument complexity, lumen characteristics, moisture retention, and the position of items or areas considered more challenging to process.

Terms such as “worst case,” “cold spot,” or “challenge location” should be used carefully. In this context, they are practical risk-assessment concepts used to identify configurations or positions that may present greater processing difficulty; they are not being presented here as universal locations or requirements established by CDC or WHO guidance.

Published variable-load validation work describes item mapping, identification of challenging configurations, and load bracketing. However, this literature is from pharmaceutical and industrial validation practice. Its concepts are illustrative for a healthcare CSSD and are not automatically a healthcare-CSSD requirement [3]. Any use of bracketing or representative configurations should be reconciled with the sterilizer, device, and packaging manufacturers’ instructions, the facility’s validated procedures, and applicable local requirements.

3. Determine the appropriate evaluation evidence

The evidence should be proportionate to the risk and magnitude of the change. Possible controls include:

• review of manufacturer instructions for the sterilizer, instruments, containers, and packaging;
• review of existing validation or qualification records;
• inspection of cycle printouts and routine monitoring results;
• use of chemical indicators in representative locations;
• biological indicator testing in an appropriate challenge arrangement;
• assessment of wetness, condensation, packaging damage, and load presentation after the cycle; and
• repeat evaluation when the proposed configuration represents a substantially different or more challenging arrangement.

CDC guidance states that, when major changes are made to packaging, wraps, or load configuration, biological and chemical indicators should be used with actual products processed in a full load. It further describes returning a changed configuration to routine use after three consecutive evaluation cycles show negative biological indicators and acceptable chemical-indicator responses, with evaluated items quarantined until results are available [1]. This recommendation must be reconciled with current manufacturer instructions, the facility’s validated procedures, and applicable local requirements. The exact protocol should be defined before evaluation begins.

4. Control the transition

During evaluation, identify affected loads so they cannot be confused with routinely released product. Define who may approve the change, who reviews the evidence, what constitutes an acceptable result, and what happens if a result is equivocal or unacceptable.

Do not rely on an external chemical indicator or a normal-looking printout as the sole justification for a new configuration. These observations are useful parts of process monitoring, but they do not replace a documented assessment of whether the proposed load has been adequately evaluated under the facility’s procedures.

5. Update the controlled documents

Once the change is accepted, update the loading diagram, work instruction, set assembly guidance, training materials, and electronic or paper load records. Include restrictions such as maximum quantity, required orientation, separation of load types, or prohibited combinations when these restrictions are part of the documented evaluation.

Training should be specific. “Load correctly” is less reliable than an image showing where a container belongs, how peel pouches are oriented, and which items must not be nested. Periodic observation or audit can help confirm that the evaluated configuration is being reproduced in practice.

What to document

A concise change-control record should include:

• description and reason for the change;
• affected sterilizer, cycle, load category, and packaging system;
• risk assessment and comparison with the established configuration;
• supporting manufacturer instructions or validation references;
• evaluation plan, including monitoring locations and acceptance criteria;
• cycle identifiers and results for each evaluation load;
• disposition of evaluated items;
• approval, date, and responsible personnel; and
• effective date and any continuing restrictions.

Packaging must remain suitable for the sterilization process and capable of maintaining the sterile barrier. ISO/TS 16775 provides guidance for evaluating, selecting, and using packaging materials, sterile barrier systems, and packaging systems, as well as validation of forming, sealing, and assembly processes [4].

Limitations and common mistakes

No generic checklist can establish that every load is acceptable. The result depends on the sterilizer design, cycle, device instructions, packaging system, load composition, monitoring approach, and local quality system. Evidence from one configuration should not automatically be treated as evidence for every possible arrangement.

Common mistakes include changing the load and packaging at the same time without separating the variables; evaluating only a lightly loaded chamber; failing to document the actual position of items selected for evaluation; treating a successful indicator as proof that all items are equivalent; and allowing staff to improvise after the change has been approved.

Practical takeaway

Load configuration is part of the sterilization process. When a routine load changes, describe the change, compare it with accepted configurations, select proportionate evaluation evidence, control the transition, and update the controlled instructions. Healthcare facilities may use risk-based and load-bracketing concepts as practical evaluation tools, but those concepts should be adapted to healthcare requirements rather than treated as automatic CSSD obligations. This approach supports operational flexibility while preserving a documented link between evaluated conditions, monitoring results, and released product.

Educational disclaimer: This article provides general technical education and does not replace applicable laws, standards, device or sterilizer manufacturer instructions, validated procedures, or qualified professional judgment.

References

1. Sterilizing Practices: Guideline for Disinfection and Sterilization in Healthcare Facilities. Centers for Disease Control and Prevention. 2023-11-28.
2. Decontamination and reprocessing of medical devices for health-care facilities. World Health Organization. 2022.
3. A Risk-Based Approach to Variable Load Configuration Validation in Steam Sterilization: Application of PDA Technical Report 1 Load Equivalence Topic. PDA Journal of Pharmaceutical Science and Technology; PubMed. 2010-03-01.
4. ISO/TS 16775:2021 — Packaging for terminally sterilized medical devices: Guidance on the application of ISO 11607-1 and ISO 11607-2. International Organization for Standardization. 2021-11; confirmed current in 2025.

Educational overview. Follow the applicable product instructions, validated procedures, local regulations and your facility’s approved policies.