Yes. Every biological indicator should be recorded with its lot number and its expiry date, on the same sheet as the sterilizer and cycle it monitored. Both fields answer questions the result alone cannot: a lot number shows which other loads ran with the same batch of indicators, and an expiry date shows whether the test was valid at the time it was run.
Why the lot number does most of the work
When a biological indicator turns positive, the question is not "did this one fail?" but "what else ran with this batch of indicators?" The lot number bounds that question. Every unit in a lot carries the same spore population from the same manufacturing run, so a positive result puts every load monitored with that lot in scope, not only the load in front of you.
It works in the other direction too. If a supplier reports a problem with a lot, the number on your sheet tells you which recorded loads are affected and which are clear. Without it, every load from that period is potentially in scope.
One habit saves most of the trouble: write the lot in when the box is opened, not when it is finished. A number added at reorder time describes the next box, not the one that was used.
The expiry on the box is not always the expiry on the unit
An in-date indicator that fails is evidence about the sterilizer. An expired indicator that fails is evidence about the shelf: the test was invalid, not the cycle. Repeat with a fresh, in-date indicator before concluding anything about the sterilizer, and note why the first result was void. A pass from an expired unit has the mirror problem, because spores that have died off cannot demonstrate lethality.
Check where the date is printed. On some formats the expiry sits on the outer box and applies to every unit inside; on others each vial or strip carries its own date. Treat a unit whose date cannot be read as out of date, and store these living products away from the sterilizer, where heat and humidity degrade them early.
What to write, and why each field earns its place
| Field | What it lets you do |
|---|---|
| Indicator lot number | Bound the scope of a positive result or a supplier recall |
| Indicator expiry date | Show the test was valid when it was run |
| Date the box was opened | Tie the units in service to that lot |
| Date and cycle the unit was used | Match each result to one specific run |
| Sterilizer and load number | Identify the machine and the load being monitored |
| Result, with the control test | Record the monitoring outcome itself |
| Operator initials | Show who performed and read the test |
Where this sits in the RCDSO self-audit form
Ontario dental practices are reviewed against the RCDSO infection prevention and control self-audit review form, and its recordkeeping expectations are specific. For each load, the log is expected to contain the date, sterilizer number, load number, load contents, cycle, sterilization time, temperature, pressure and the name of the person responsible. Package labels, a service and maintenance log, and malfunction records make up twenty official fields across those four areas.
Two expectations sit closest to this article: a biological indicator with a control test completed once daily for each type of cycle, and a logbook kept for at least ten years after the last entry. Neither can be demonstrated if the indicator lot and expiry were never written down. The form names no "BI lot number" field, and that is the point: the lot record is what lets a clinic answer the recordkeeping items truthfully when a result is questioned years later.
| What happened | What the record has to show |
|---|---|
| Indicator passes, in date | Lot, expiry and cycle — the evidence base for the retention period |
| Indicator fails, in date | Lot and expiry so the failure is valid, then the repeat result |
| Expired unit fails | Why the test was void, and the result of the in-date repeat |
What an inspector is really testing
When an inspector or a college reviewer opens a sterilization log, the underlying question is whether the clinic can reconstruct what happened to a specific set of instruments. That is a liability question as much as a compliance one: if a patient later asks whether the instruments used on them were sterile, the answer comes from the record, and the record either has a lot number beside that cycle or it does not.
Records are what shrink a problem from "everything" to "these loads". Indicators printed with a lot and an expiry make that possible: a 24-hour self-contained biological indicator returns a result the next day, a five-pack indicator trial starts daily monitoring this week, and a load of indicator tape keeps the chemical layer of the record complete.
References
- Public Health Ontario — infection prevention and control guidance
- PIDAC — cleaning, disinfection and sterilization of medical equipment in all health care settings
Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers case pricing and account setup, and the B2B wholesale collection lists the lines stocked for institutional buyers.
Related reading
Keeping the monitoring record complete:
- Sterilization compliance hub
- Sterility assurance level (SAL) explained
- Rebuilding a sterilization log after an inspection
- The audit-ready autoclave log
- Spore testing protocols for Canadian clinics
- Rapid Readout Biological Indicator Readers: Every Major Brand Compared (2026 Canada Price Guide)
- BI vs Chemical Indicators: What's the Difference in Sterilization Monitoring?
- The Real Annual Cost of Biological Monitoring: Locked Ecosystems vs Open-System BIs in Canadian Dental Clinics
- sterilization compliance log sheet (free tool)
- printable autoclave sterilization log sheet (free)
Frequently Asked Questions
Do I need to record the lot number on every biological indicator?
Yes. The lot number is the field that lets you find every load that ran with the same batch if a result is positive or a supplier reports a problem. It takes a few seconds to copy from the box and it is the difference between a bounded list and an open question.
What if an expired biological indicator shows a pass?
Treat the test as invalid and repeat it with an in-date unit. Spore viability falls as the product ages, so a pass from an expired indicator does not demonstrate that the cycle killed a full population of spores. Note on the record why the first test was set aside.
How long do sterilization records have to be kept in Ontario?
The RCDSO self-audit expectations call for the logbook to be kept for at least ten years after the last entry. Keep the monitoring results, equipment check sheets and cycle printouts for the same sterilizer together so a reviewer can follow one machine through the period.
Where should the lot number and expiry be written?
On the same log entry as the cycle the indicator monitored, and on the box when it is opened. Writing the lot only at reorder time records the wrong box.
Does the lot number still matter if every result has passed?
Yes. Passing results become the record you rely on later: they show the cycle was monitored, they support the ten-year retention requirement, and they are what a clinic consults if the same lot is later questioned.
CliniEco Medical holds MDEL #35334 and supplies sterilization monitoring and infection control consumables to Canadian clinics, long-term care homes and dental practices.
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