When an autoclave cycle is interrupted mid-run, the load is not sterile and must not be used, even if the interruption happened near the end and the instruments look dry. The correct action is to close the cycle record with a deviation note, re-run the full cycle from the start, and release the load only after a valid cycle and, where required, a biological indicator result. A power blip, an opened door or a fault code all put you in the same position.
The instinct to rescue the cycle is strong when a clinic is busy, which is why the rule should be written before it happens. Keep a 24-hour biological indicator available so the re-run can be verified rather than assumed.
What should be done in the first five minutes?
| Step | Action | Reason |
|---|---|---|
| 1 | Do not open the door until the chamber pressure has equalised | Opening under pressure is a burn risk |
| 2 | Mark the load as unsterile and move it to the dirty side | Prevents accidental use |
| 3 | Record the fault code, time and cycle stage | The record is needed for the re-run and the service call |
| 4 | Check the obvious causes: power, water supply, door seal, overload | Many interruptions are simple and repeatable |
| 5 | Re-run the full cycle from the start | A partial cycle cannot be resumed |
Can the cycle be resumed where it stopped?
On some sterilizers there is a resume function, and it is tempting to use it. The safe position is that a resumed cycle is a new cycle only if the unit has completed the full sequence from the beginning. A cycle that resumes after a vacuum interruption has not re-established the conditions for the whole load, and the instrument set may have been exposed to moist heat without the full hold time. Re-run from the start.
If the interruption happened during the drying phase after a full sterilization hold, the load may be sterile but wet. A wet pack is not a valid pack: moisture can wick contaminants through the packaging. Dry the load per the manual or reprocess it, and record which option you took.
Does an interrupted cycle need a biological indicator?
Yes, if the load is to be released. The re-run is a new cycle, and the normal monitoring rule applies to it. A clinic that runs one test per sterilizer per day may not have planned for a second test that day, which is why keeping spare indicators matters. In Ontario dental practice, the daily requirement is a test for each sterilizer on every day it is used, and an interrupted cycle does not remove that obligation.
If a positive indicator follows an interrupted cycle, treat it as a process failure and work through the usual checks before assuming the interruption caused it. The interruption may be a symptom of the same fault.
What should be recorded?
Record the date and time, the cycle type, the stage at interruption, the fault code or cause, the items in the load, the action taken (re-run, dry, discard) and the result of the re-run. Add the indicator result if one was used. This record is what distinguishes a managed interruption from an unrecorded event, and it is the first thing a reviewer will look for if a patient question arises later.
Keep the record in the cycle log sequence, not in a separate incident file. The next person reading the log should see the interruption and the recovery in order.
How can interruptions be reduced?
Three practical steps. Keep the water reservoir filled and the drain clear, because a low-water fault is a common interruption. Avoid loading the chamber to its limit, since an overload can trigger a fault mid-cycle. And check the door seal and hinge, because a pressure leak can abort a cycle. A maintenance schedule that covers these three items prevents most avoidable interruptions.
For a single-sterilizer clinic, plan a contingency: a backup unit, a service agreement with a response time, or an arrangement with a nearby practice. An interruption is manageable; an interruption with no backup capacity becomes a cancelled clinic day.
What about the items that were in the load?
Treat them as contaminated until they have been through a full valid cycle. If they were cleaned and packaged before the interrupted cycle, they can usually be re-run without recleaning, provided they stayed dry and the packaging is intact. If the packaging is wet or damaged, reclean and repack. Record which path was taken for each load, because the decision affects the release.
Related reading
- Spore test positive: what a clinic must do before using the load again
- How to load an autoclave: chamber loading mistakes
- Autoclave door seal replacement: how often and how to check
Download the printable sterilization log, or build one with the log generator. Ask a Compliance Specialist at our consultation desk. Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers account setup for institutional buyers. Start with a 24-hour biological indicator 25-pack so a spare test is always on the shelf. Reselling? become a distributor.
Frequently Asked Questions
Is a load sterile if the cycle was interrupted near the end?
No. A partial cycle cannot be treated as a completed cycle. Re-run the load from the start and release it only after a valid cycle.
Can I resume an interrupted autoclave cycle?
Only if the unit completes the full sequence from the beginning. A resume that skips part of the vacuum or hold stage does not sterilize the whole load.
Do I need a new biological indicator after an interruption?
Yes, for the re-run. The re-run is a new cycle and the normal monitoring rule applies to it.
What should I do with wet packs after an interruption?
Do not use them. Dry per the manual and verify the packaging, or reclean, repack and re-run. Record which option was taken.
CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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