2 of 10

What is Event Related Sterility?

Core principle

A properly sterilized item remains sterile until an event occurs that compromises the sterile barrier or otherwise creates a contamination risk.

Think beyond a date

Sterility is not determined only by a calendar expiry date. Packaging integrity, storage, transport and handling determine whether sterility has been maintained.

Key question before use

“Has anything happened to this package since sterilization that could have compromised its sterility?”

3 of 10

Sterility is a process not a single sterilizer cycle

Cleaning

Inspection & assembly

Packaging

Sterilization

Cooling & storage

Point-of-use inspection

If any critical step fails, the final device may be unsafe—even when the sterilizer cycle itself was successful.

4 of 10

Events that compromise sterility

Wet / damp pack

Moisture can permit microbial migration through packaging.

Torn, punctured or opened pack

Barrier integrity has been lost.

Dropped on floor

Impact can damage packaging or expose it to contamination.

Crushed or heavily compressed pack

Packaging may be weakened or compromised.

Seal failure / broken closure

The sterile barrier is no longer reliable.

Excessive handling

Repeated handling increases risk of damage and contamination.

Improper transport or storage

Dust, moisture, traffic and poor storage can compromise packs.

Unknown processing status

No reliable cycle/traceability evidence = do not use.

5 of 10

Point of use inspection

Packaging

Dry? Intact? No tears, punctures, holes or opened seams?

Seal / closure

Intact and secure? No separation, lifting or channel defects?

Indicators / label

Correct load information and acceptable chemical indicator result?

Cleanliness

No visible soil, stains, dust or contamination?

Traceability

Cycle/load can be identified according to facility policy?

Instrument condition

No rust, damage, residue or obvious processing problem?

6 of 10

Wet pack: A sterility failure event

Why it matters

A wet or damp package should be considered compromised. Moisture can create a pathway for microorganisms to move through packaging.

Immediate action

Do not release for use.��Quarantine the affected item/load as required by local policy.��Identify and document the event.

Corrective action

Determine the cause—loading, drying, equipment, packaging, water quality or process issue.��Repackage and reprocess when required.

7 of 10

Storage environment

Keep sterile packs in a clean, dry, controlled storage area protected from dust, moisture and unnecessary traffic.
Use shelving that prevents packs from being crushed, damaged or placed directly on the floor.
Minimize handling—handle packs gently and only when necessary.
Separate sterile stock from contaminated/dirty items and unrelated materials.
Rotate stock using the facility’s approved stock-management method; event-related sterility means integrity is the key determinant.
Inspect packages before dispatch and again at point of use.

8 of 10

Transport: the sterile barrier must survive the journey

Before transport

• Verify pack integrity�• Use clean, dedicated transport equipment�• Protect from moisture and dust�• Avoid overloading�• Keep sterile items separate

During transport

• Avoid dropping or dragging packs�• Minimize unnecessary handling�• Protect from traffic and environmental contamination�• Keep carts/containers clean

At destination

• Inspect before storage/use�• Reject damaged or wet packs�• Maintain traceability�• Report transport-related events

9 of 10

Quality assurance

Use written policies and standardized work instructions for storage, transport and point-of-use inspection.
Maintain sterilization records and traceability according to applicable standards and local requirements.
Monitor equipment performance, packaging quality, storage conditions and transport practices.
Trend events such as wet packs, damaged wrappers, failed indicators and missing documentation.
Use incident review / root-cause analysis for repeated or significant failures.
Train staff regularly and verify competency.

10 of 10

References

World Health Organization (WHO). Decontamination and reprocessing of medical devices for health-care facilities: aide-memoire (2022).
World Health Organization (WHO). Decontamination and reprocessing of medical devices for health-care facilities (2016).
Centers for Disease Control and Prevention (CDC). Sterilization—Packaging & Storage FAQ: event-related shelf-life principles.
ANSI/AAMI ST79:2017/(R)2022, with amendments A1–A4: Comprehensive guide to steam sterilization and sterility assurance in health care facilities.
Facility policies, manufacturer Instructions for Use (IFU), and applicable national regulatory/accreditation requirements should always be followed.

1 of 10