Immediate-Use Steam Sterilization: When Flash Cycles Are Permitted and What They Require

Three rolls of steam sterilization indicator tape of the type used to seal an unpackaged instrument tray
Three rolls of steam sterilization indicator tape of the type used to seal an unpackaged instrument tray

Immediate-use steam sterilization — the process that was once called "flash sterilization" — is a steam cycle for items that will not be stored, wrapped and returned to a shelf, but used almost as soon as the cycle ends. It is allowed in a narrow set of circumstances, it is prohibited in a wider one, and most of what decides which is which is not about the sterilizer at all. It is about the device, the load, and what the facility can show afterwards.

For a clinic manager, the practical question is rarely whether the cycle works — a validated cycle works — but when choosing it puts the facility outside its own college's or province's standard. This article answers that by setting out what the process is, which items it may and may not touch, what it has to record, and where the line between permitted and non-compliant falls.

Sources are the Ontario standard of practice for infection prevention and control, Public Health Ontario's provincial guidance on cleaning, disinfection and sterilization, the multi-society United States position statement on immediate-use steam sterilization, the CDC flash sterilization guidance, and the AAMI steam sterilization standard.

Quick facts

  • "Immediate-use steam sterilization" replaced the older term "flash sterilization" because the cycles now used for these items are not always the short, unwrapped cycles the word "flash" described.
  • It is defined as the shortest possible time between a sterilized item leaving the sterilizer and its aseptic transfer to the point of use — it is not defined by a stopwatch number of seconds.
  • The Ontario standard permits what it calls an unpackaged cycle only in URGENT situations where no other option is available, and never for implantable devices.
  • It must not be used to make up for a thin instrument inventory, or to save time when a wrapped cycle was possible.
  • An immediate-use cycle still requires thorough cleaning and drying, process monitoring, a record per instrument, and sterility maintained during transport to the point of use.

What is immediate-use steam sterilization, and why is it no longer called flash sterilization?

Immediate-use steam sterilization (IUSS) is a steam sterilization process used when an item cannot be packaged, sterilized and stored ahead of time, and must be made ready during the procedure for which it is needed. The older term, flash sterilization, described a narrow version of it: an unwrapped object exposed to steam for a short time and rushed to the field. Public Health Ontario's provincial guidance still carries the older name in brackets, but defines the process plainly as a special steam sterilization process designed and used for the emergency sterilization of surgical goods when routine sterilization cannot be done.

The multi-society United States position statement explains why the name moved. "Flash sterilization" arose from the abbreviated exposure time of the unwrapped device, but current guidelines may require longer exposure times and the use of single wrappers or containers designed for aseptic transfer. The statement calls the old term antiquated, because it no longer describes the range of cycles in use, and adopts immediate-use steam sterilization as the more accurate name. The distinction matters for a buyer because it tells you the process is not automatically the shortest, least-monitored available cycle — it is the process used when storage is impossible, and it carries the same critical reprocessing steps as any other load.

What does AAMI ST79 require for immediate-use cycles?

AAMI ST79, the American National Standards Institute's recommended practice for steam sterilization and sterility assurance in health care facilities, is the document that anchors the North American consensus on immediate-use cycles. Its published scope is steam sterilization in health care facilities regardless of sterilizer size, and it is the standard to which the multi-society immediate-use position statement and the CDC guideline both refer.

Two things about ST79 are worth being precise about for a Canadian reader. It is a United States recommended practice, not a Canadian legal requirement, and its immediate-use provisions rest on the same principle the Canadian documents use — that the decision to run such a cycle is governed by the device and the load, not by convenience. Table 1 sets out the device-and-load rules as they appear across the documents a Canadian facility is most likely to be measured against.

Device or load Immediate-use / flash permitted? Source of the rule
Implantable devices (dental implants, temporary anchorage devices, surgical screws, plates, staples) Not permitted; must never go through an unpackaged cycle RCDSO IPAC standard; PHO provincial guidance (Recommendation 58)
Complete sets or trays of instruments Not permitted PHO provincial guidance
Items used on patients who may have Creutzfeldt–Jakob disease or similar disorders Not permitted as a post-procedure decontamination route Multi-society IUSS position statement
Devices that have not been validated with the specific cycle employed Not permitted Multi-society IUSS position statement
Devices sold sterile and intended for single use only Not permitted Multi-society IUSS position statement
A single cleaned instrument needed urgently, where no other option exists Permitted, with the full set of conditions in Table 2 RCDSO unpackaged-cycle requirements; PHO section 2.L
Scheduling convenience, low inventory, or saving time Not a permissible reason CDC flash sterilization guidance; PHO provincial guidance

What does the Ontario standard say about an unpackaged cycle?

The Royal College of Dental Surgeons of Ontario sets out the Ontario position under the heading "Sterilization of unpackaged instruments." It defines an unpackaged sterilization cycle — sometimes called flash sterilization or immediate use sterilization — as a method for sterilizing patient-care items for immediate use, and then draws a hard boundary: it must only be used in URGENT situations in which no other option is available, must not be used to compensate for a low inventory of instruments, and must never be used for implantable devices.

For the situations in which it is used, the Ontario standard lists the conditions that have to be met: a record is kept for each instrument undergoing unpackaged sterilization, including the name of the patient, procedure, dentist and instrument used; thorough cleaning and drying of instruments precedes the cycle; physical indicators and Type 5 or Type 6 chemical indicators are used and checked at the end of the cycle; care is taken to avoid thermal injury to staff or patients; and the sterility of the instruments is maintained during removal from the sterilizer and transport to the point of use.

Public Health Ontario's provincial guidance reaches the same conclusion in its own words, adding the framing that "sterilization is a process, not an event," and that operative scheduling and a lack of instrumentation do not qualify as reasons to use immediate-use steam sterilization. Its recommendation is worded in the same terms as the Ontario college standard: the process is for emergency situations only and must never be used for implantable devices. The CDC's flash sterilization guidance agrees on the implant rule and adds the recordkeeping rationale: where an implantable device cannot be avoided, load identification, the patient identifier and the biological indicator result become essential for epidemiological tracking.

When does using an immediate-use cycle cross into a compliance breach?

This is the question the neighbouring explanations tend to skip. The rule is not "immediate-use is banned." It is "immediate-use is conditionally permitted," and a facility has crossed the line when any one of the following is true. Table 2 turns that into a check a manager can run before the fact.

Trigger Why it is a breach Where the rule comes from
An implantable device went through an unpackaged cycle Implants are excluded outright, because a shortened, unmonitored cycle cannot stand behind a permanent device RCDSO; PHO Recommendation 58; CDC
The cycle was run for scheduling convenience, to save time, or to cover a low instrument inventory These are not emergency situations, and they are the reasons the process is restricted in the first place CDC; PHO section 2.L
The device or load was never validated with the specific cycle used An unvalidated device-and-cycle pairing cannot demonstrate sterility Multi-society IUSS position statement
No per-instrument record was kept (patient, procedure, practitioner, instrument) The record is what makes the cycle auditable after the fact RCDSO unpackaged-cycle conditions
Cleaning and drying were skipped or abbreviated before the cycle Immediate-use changes the packaging and monitoring, not the cleaning; soil load defeats the cycle RCDSO; multi-society IUSS position statement
Sterility was not held during removal from the sterilizer and transport to the point of use The item is sterile only until it is exposed to air without protection RCDSO; PHO section 2.L
The item was used on a patient who may have had CJD or a similar disorder Immediate-use is not a valid post-procedure route for those instruments Multi-society IUSS position statement

A facility that can answer "no" to every row in Table 2 is using immediate-use inside the boundary the standards draw; a "yes" on any row is a corrective item, not a sterilizer fault.

How does the Ontario daily biological indicator rule apply to these loads?

Ontario's biological monitoring rule is the same whether the load was wrapped or unpackaged. The college standard requires a biological indicator to be placed in a process challenge device and used to test the sterilizer each day that it is used and for each type of cycle that is used. In plain terms, an Ontario dental office runs one biological indicator per sterilizer per day it is used, and covers each cycle type separately — not one indicator a week.

That daily cadence is the Ontario requirement. The weekly biological indicator schedule that appears in many English-language summaries is the United States baseline associated with the CDC guidance and ANSI/AAMI ST79; it is not the Ontario requirement, and it does not satisfy the college's daily rule. The two are often written side by side, but they belong to different jurisdictions, and a clinic reading a supplier's blog should check which rule is being quoted before it changes anything on the log.

Immediate-use loads do not escape the daily rule, and they add a second one. In addition to the daily biological indicator, every load containing an implantable device must carry a biological indicator in a process challenge device, and the implantable devices must be quarantined until the result is known. Because immediate-use is itself prohibited for implants, the two rules in practice pull in the same direction: the implant either waits in quarantine behind a biological indicator, or it does not go through the sterilizer.

What an immediate-use cycle has to leave behind

Read as a whole, the immediate-use rules are really a documentation test. The cycle itself is short; the record is what a facility keeps. The Ontario standard asks for a per-instrument record naming the patient, the procedure, the dentist and the instrument, with the same information reflected in the patient record. Public Health Ontario adds that the load printout must be signed to verify the required time, temperature and pressure were reached, and that records be reviewed regularly to correct overuse of the process — a facility documenting immediate-use every week has found a process problem, not a monitoring problem.

On the monitoring side, the physical indicators and the Type 5 or Type 6 chemical indicators are checked at the end of the cycle, and the biological indicator sits at the daily frequency above. Where the packaging and indicator side of those loads is being set up, the material side is covered by Class 4 dual-indicator sterilization pouches and the external monitor side by sterilization indicator tape. Facilities building out the monitoring programme, including the load-release question that runs alongside immediate-use, can start with a biological indicator trial pack before ordering case quantities, and case-level ordering runs through the wholesale account page. Reselling? become a distributor.

The wider map for this topic is the sterilization compliance hub, which gathers the steam, monitoring and recordkeeping material in one place. Teams deciding how often to run a spore test in the first instance, wrapped or unpackaged, can start from how often a spore test needs to run, and readers who want the standard-level background on which sterilizer requirement applies to which machine can read the comparison of EN 13060 and EN 285. A spore strip is only as meaningful as the lethality target behind it, which is where sterility assurance level becomes relevant.

Before the next unpackaged cycle, the two pieces worth having on the wall are the record format an inspector will compare against and the working log itself. The compliance log centre provides a printable blank sheet built on the four record groups and twenty fields that the Ontario record-keeping form uses, so a facility's own paper and the form it is measured against line up term for term. The same page generates a dated load-log page from the same fields, in the browser, without an account — the version a clinic can hand to whoever is running the cycle that day.

Have a question about your own facility? Send it in and you will get a written answer specific to your setup, with the regulation or standard it is based on cited. Ask your compliance question.

Where to Buy Biological Indicators in Canada

CliniEco Medical supplies these from Ontario with published CAD pricing (MDEL #35334) — no quote required, and each pack ships with the lot number printed on it so your monitoring record stays traceable.

Format Pack size Price (CAD)
24-hour self-contained 25-pack $84.99 Order
24-hour self-contained 100-pack $299.00 Order
3-hour rapid fluorescence 50-pack $274.99 Order

Round Out Your Sterilization Setup

A biological indicator is one link in the chain — these are the pieces it works with:

Which format does your sterilizer actually need?

Match the readout time to how fast you need the result: a 24-hour self-contained indicator works in any gravity or pre-vacuum cycle with a standard incubator, while a 3-hour fluorescence tube needs the matching reader. Running one cycle type per day, the 25-pack covers a month; busier clinics move to the 100-pack and cut the per-test cost.

How much do spore tests cost in Canada?

Published pricing runs $3.40 per test on the 25-pack down to $2.99 on the 100-pack — no distributor quote, no account needed.

Not sure which format your sterilizer needs? Generate a free sterilization log sheet first — it maps your cycles and tells you the pack size that fits. Questions about your setup? Ask a Compliance Specialist.

Related reading

A paper spore strip biological indicator labelled for steam sterilization, of the type used in a daily sterilizer test

Frequently Asked Questions

Is immediate-use steam sterilization the same as flash sterilization?

It is the process the older name referred to, but the names are not interchangeable in current guidance. Flash sterilization described an unwrapped item exposed briefly and used quickly; immediate-use steam sterilization is the term the multi-society statement adopted because today's cycles may use longer exposures and single wrappers or containers for aseptic transfer. The shift is not cosmetic — it signals that the process carries the same critical reprocessing steps as any other load.

Can immediate-use steam sterilization be used for dental implants?

No. Implantable devices — dental implants, temporary anchorage devices, and surgical screws, plates or staples — must never go through an unpackaged immediate-use cycle. Implants must instead be placed in a load with a biological indicator in a process challenge device and quarantined until the result is known. The prohibition is stated in the Ontario college standard, in Public Health Ontario's provincial guidance, and in the CDC guidance.

What is a permissible reason to run an immediate-use cycle?

An emergency: a single cleaned instrument is needed urgently and no other option is available. Scheduling convenience, a shortage of instruments, and a wish to save time are not permissible reasons, and Public Health Ontario states directly that a lack of instrumentation and operative scheduling do not qualify. A facility that routinely runs these cycles has an inventory or workflow problem to fix, not a monitoring programme to trust.

Does an immediate-use load still need a biological indicator?

Yes. Ontario's daily rule applies regardless of how the load was packaged: a biological indicator in a process challenge device tests the sterilizer each day it is used and for each type of cycle used. The weekly biological indicator schedule seen in many summaries belongs to the CDC and ANSI/AAMI ST79 United States baseline, not to Ontario, and does not replace the daily requirement.

What must be recorded for each instrument sterilized by an unpackaged cycle?

The Ontario standard requires a record for each instrument that includes the patient's name, the procedure, the dentist and the instrument used, with the same information reflected in the patient record. Public Health Ontario adds that the load printout is signed to verify the required time, temperature and pressure were achieved and that records are reviewed regularly to correct overuse of the process.

Why does the Ontario standard call it an unpackaged cycle instead of flash?

Because the defining feature it regulates is the absence of protective packaging, not the speed. The college standard groups "flash sterilization" and "immediate use sterilization" under the heading of unpackaged instruments, and then regulates the missing wrapper: no storage, no hold from one case to the next, and sterility preserved only through aseptic transfer to the point of use.

Do these rules apply outside Ontario?

The Ontario college standard binds Ontario dental practices. Other provinces set their own frequency for biological monitoring, so a clinic should follow the regulator for the province it operates in rather than importing Ontario's daily rule or the United States weekly baseline. The immediate-use restrictions on implants, however, recur across the Canadian guidance and the United States position statement alike.

Is a tabletop sterilizer held to a different rule?

No. The immediate-use restrictions follow the device and the load, not the size of the machine. A bench unit in a dental operatory is held to the same implant prohibition, the same cleaning-and-drying requirement, and the same daily biological monitoring as a larger unit, because the governing documents are written around the process and the item rather than the chamber volume.

CliniEco Medical holds Medical Device Establishment Licence MDEL #35334. This article compares published standards, regulatory documents and public guidance and does not make a sterilization performance claim for any product.

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