Quick answer: No single check proves a surgical tray is sterile. Reliable CSSD sterilisation indicators work in layers — steam indicator tape on the outside of the pack, a daily Bowie-Dick test on the machine itself, and chemical and biological indicators inside every pack. Here's what each one actually tells you, and how to build a routine around them.
Why Do You Need More Than One Sterilisation Indicator?
A steriliser can complete a "normal" cycle and still fail. Trapped air, an overloaded chamber, wet steam or a worn door seal can each stop steam reaching every surface — and the display won't always warn you. Good CSSD practice never relies on one check; each indicator answers a different question, and together they close the gaps a single test would miss.
What Does Steam Indicator Tape Actually Tell You?
Steam indicator tape (often called autoclave tape) is stuck to the outside of wrapped packs and changes colour once exposed to steam at temperature. Its job: separate processed packs from unprocessed ones, so nothing unprocessed reaches the operating theatre by mistake.
Know its limit. A colour change confirms exposure to heat and steam — it does not prove the contents are sterile. Treat it as a first-line visual check, never a release decision on its own.
How Does the Bowie-Dick Test Work?
In pre-vacuum cycles, the machine removes air from the chamber before steam enters. If air remains trapped, steam can't penetrate fabric packs and hollow instruments properly — the Bowie-Dick test checks exactly this: air removal and steam penetration.
Run it in an empty chamber first thing each working day, before any real loads go through. A uniform colour change across the test sheet is a pass. An uneven change — often a paler centre — signals an air-removal fault, and the steriliser should be pulled from use until it's investigated and re-tested. Always follow your manufacturer's instructions and the CDC's sterilisation guidelines for exact test conditions.
What Are Chemical Indicators Used For in CSSD?
Chemical indicators go inside the pack, right where the instruments sit, reacting to variables like temperature, time and steam quality. Some track a single variable; integrating indicators track several for a more reliable read. Place one where steam is least likely to reach, so whoever opens the tray can verify the result at the point of use. If it hasn't changed as specified, the tray doesn't get used.
Why Are Biological Indicators the Gold Standard?
Biological indicators contain bacterial spores highly resistant to steam. After a cycle, they're incubated — any growth means sterilisation failed. It's the most direct evidence a cycle actually worked, which is why the CDC's disinfection and sterilisation guideline recommends running them at set intervals and with every implant load.
Does Wrapping Material Affect Sterilisation Indicators?
Yes — indicators only work if the packaging lets steam in and keeps contaminants out afterwards. Crepe paper and SMS (spunbond-meltblown-spunbond) wrap are built for this. Match the grade to your load, wrap consistently, and avoid packs too tight or bulky for steam to penetrate evenly.
A Simple Daily CSSD Sterilisation Checklist
- Apply steam indicator tape to every wrapped pack
- Run a Bowie-Dick test each morning before the first load
- Place a chemical indicator inside every pack
- Run biological indicators at your protocol's set intervals
- Log every result against load numbers for traceability
Written records matter — if a problem surfaces later, traceability lets you trace exactly which packs came from the affected load.
Sourcing Reliable CSSD Consumables
Consistent indicator quality is what makes this system trustworthy. LIFORAMED supplies CSSD consumables including steam indicator tape, crepe and SMS wrapping paper, and Bowie-Dick and chemical steam tests, alongside the wider range your sterile processing department needs.
Related reading: our PPE compliance checklist for diagnostic centres and pathology labs.
Want help specifying the right range for your facility? Request a quote and our team will walk you through it.