ISO 13485 · Expert · 13 min lesson
Sterilization methods overview: EtO, gamma, steam and the ISO 11135, 11137 and 17665 families
ISO 13485:2016 clauses 7.5.5, 7.5.7 and 4.1.5; ISO 11135, ISO 11137-1 to -3, ISO 17665:2024, ISO 11607
What you will learn
- Compare ethylene oxide, radiation and moist heat by principle, material and pack compatibility, and residuals.
- Link each method to its standard family (ISO 11135, ISO 11137, ISO 17665) and to clause 7.5.7 and 7.5.5 of ISO 13485.
- Read a sterilization validation file, name the roles of a contractor and spot a weak record.
Key takeaways
- Clause 7.5.7: validate sterilization and sterile barrier systems before implementation and after changes; clause 7.5.5 requires batch parameter records.
- Ethylene oxide follows ISO 11135, radiation the ISO 11137 family, and moist heat ISO 17665:2024; confirm the edition in force.
- Method choice follows material tolerance, sterile barrier system, penetration, residuals and controllability, not price.
- Validation has a physical half (mapping) and a microbiological half (indicators or bioburden based evidence).
- Outsourcing to a contract sterilizer keeps responsibility with you under clause 4.1.5: agreement, certificate review, audits.
Free practice question
Norvane moulds a surgical guide in a polymer that softens above 80 degrees Celsius. A purchasing colleague proposes moist heat at a contractor because it has the cheapest price and shortest cycle. The file contains no material compatibility data.
What should the quality manager require before accepting this method?
A documented rationale showing the polymer and pack tolerate the method, or a different method.
Correct. Clause 7.5.7 requires a validated process, and the rationale must show material compatibility before any cycle is developed.
Nothing more, because the price comparison is the rationale.
Not quite. Price cannot replace technical evidence of compatibility, which clause 7.5.7 validation needs as its starting point.
A printout of one cycle at the contractor.
Not quite. One printout shows that a cycle ran, not that the polymer survives it, so clause 7.5.7 is not met.
A statement from the sales team that customers accept it.
Not quite. Customer acceptance is not objective evidence of compatibility or sterilization performance under clause 7.5.7.
Key terms
- sterilization: A validated process that renders a product free of viable microorganisms to a defined sterility assurance level.
- ethylene oxide: A reactive gas used at low temperature to sterilize heat sensitive devices; governed by ISO 11135.
- radiation sterilization: Sterilization by dose in kilograys from gamma, electron beam or X-ray; the ISO 11137 family.
- moist heat: Sterilization by saturated steam under pressure; governed by ISO 17665:2024.
- biological indicator: A test system containing resistant spores used to challenge a sterilization process.
- sterile barrier system: The minimum package that prevents microbial ingress and allows aseptic presentation; ISO 11607.
- dose audit: A periodic check that the established radiation sterilization dose remains appropriate for current bioburden.
- certificate of processing: The contractor's record of the parameters and dose or cycle data applied to a load.
Official sources
- ISO 17665:2024 Sterilization of health care products - Moist heat
- ISO 11135:2014 Sterilization of health-care products - Ethylene oxide
- ISO 11137-1 Sterilization of health care products - Radiation - Part 1 (2006 edition page, withdrawn; replaced by the 2025 edition)
- International Irradiation Association: new revision of ISO 11137-1:2025 published
- ISO 13485:2016 Medical devices - Quality management systems
Go further
The full lesson has narrated slides, more scenario questions with explained answers and a simulation.
Open the AcademyWatch on YouTubeIllustrative example. Educational only, not legal advice.