Sterilite – ISO 11737-2

What Is Sterility — ISO 11737-2?

The sterility test under ISO 11737-2 is used in verifying and maintaining the sterilisation process. The product is incubated in a suitable medium to show whether viable micro-organisms are present. This test alone does not prove a batch is sterile; it is part of the sterilisation process validation.

Purpose of Sterility — ISO 11737-2

The purpose is to show the process's effectiveness in validation studies such as reduced dose or half-cycle. Releasing the product as sterile relies not on batch-based sterility testing but on a validated, monitored sterilisation process.

Which Products Is Sterility — ISO 11737-2 Applied To?

Sterile single-use medical devices
Surgical sets and drapes
Implants
Sterile-packaged catheters and needles
Sterilisation process validation specimens

In Which Sectors Is Sterility — ISO 11737-2 Used?

Medical DevicePharmaceuticalsHealthcareBiotechnology

Standards Related to Sterility — ISO 11737-2

ISO 11737-2sterility test in sterilization verification test

Sterility — ISO 11737-2 Conditions

Method: Direct immersion or membrane filtration
Culture medium: Media supporting aerobic and anaerobic growth
Incubation: Temperature and duration defined in the standard
Method suitability: A suitability study showing the product does not inhibit growth is performed first

Equipment for Sterility — ISO 11737-2

Grade A/B sterile working area or isolator
Membrane filtration setup
Temperature-controlled incubators
Autoclave and media preparation equipment
Environmental monitoring systems

Sample Requirements for Sterility — ISO 11737-2

The specimen must be sent with its sterile packaging intact, in the number defined in the validation plan.
The specimen must represent the hardest-to-reach point of the sterilisation process.
It must be stated whether the product contains a component that inhibits growth in the medium.
Packaging integrity must be maintained during transport.

Duration of Sterility — ISO 11737-2

The incubation period is defined in the standard and runs up to two weeks. The method suitability study adds to this beforehand.

Sterility — ISO 11737-2 Procedure

1A method suitability study is performed, showing the product does not inhibit growth.
2Specimens are opened under aseptic conditions.
3Direct immersion or membrane filtration is applied.
4Media are incubated at the defined temperature and duration.
5Growth is observed regularly.
6Micro-organisms are identified in vessels showing growth.
7The result is carried into the validation file.

Sterility — ISO 11737-2 Acceptance Criteria

The acceptance criterion is selected from the relevant section of the standard according to the device's contact type (surface, externally communicating, implant), contact duration and intended use. The assessment relies not on a single test result but on the biological evaluation plan carried out under ISO 10993-1; this page therefore gives no fixed limit.

Evaluation of Results

The assessment includes investigating whether growth stems from an inadequate sterilisation process or contamination during the test itself. The decision to release the sterile product relies not on batch sterility testing but on parametric control of the validated process.

Sterility — ISO 11737-2 Report

Device identification, model and lot number, if any
Device contact type, duration and intended use
Standard and section applied
Extraction or sample preparation conditions
Cell line, test system or test rig used
Controls and their results
Observations, measurement results and assessment
A statement that the result applies only to the specimen submitted for testing

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

EU 2017/745 Medical Device Regulation (MDR)
Medical Device Regulation (Türkiye)
ISO 14971 (risk management for medical devices)
ISO 13485 (medical devices — quality management system)

Medikal Cihaz Testleri — What Does This Testing Field Cover?

The section below describes the field that the Sterility test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Medical device testing shows that a device is safe for the patient and the user and maintains its intended performance. In this family safety is not only about avoiding harm; a device failing to perform its expected function is also treated as a risk. A monitor missing an alarm or a pump delivering the wrong dose is directly a patient safety event.

At the centre of the field is RISK MANAGEMENT, and this is what sets medical apart from other sectors. The risk management process run under ISO 14971 also determines which tests are required. The test list is not copied from a table of standards; it is derived and justified from the device's intended use, the nature and duration of patient contact, the use environment and foreseeable misuse.

Assessment consists of several separate bodies of work, each with its own set of standards. Biocompatibility runs through the ISO 10993 series, electrical device safety through the IEC 60601 series, sterilisation through ISO 11135/11137/17665, packaging through ISO 11607, software through IEC 62304 and usability through IEC 62366. The quality system (ISO 13485) is the framework that binds these together.

Which tests are required is determined by the device's CLASS and its MODE OF CONTACT WITH THE BODY. A product in brief contact with skin and an implant entering the bloodstream do not go through the same test set; the scope is set by a biological evaluation plan prepared under ISO 10993-1. That plan justifies in writing which endpoints are required and why the others are not.

Packaging and sterilisation are taken as seriously as the device itself in this field. For a sterile device the packaging is not a transport container but the barrier that maintains sterility; if the barrier is breached, the device is no longer sterile. Packaging processes are therefore validated and shelf life is supported by real-time ageing data.

For devices containing software, assessment shifts from testing towards PROCESS assurance. IEC 62304 defines which development and verification steps must be followed according to the safety class of the software; the evidence is the traceability of the development process. Testing software does not make it safe — the process record does.

The clinical side is a separate column of the technical file. Test reports show that the device is technically safe; clinical evaluation establishes that the device delivers the intended clinical benefit and that the benefit-risk balance is acceptable. Neither replaces the other.

Method groups in this field

Biocompatibility
Cytotoxicity, irritation, skin sensitisation, systemic toxicity, haemocompatibility, genotoxicity and local effects after implantation. The required endpoints are set by the ISO 10993-1 plan.
Electrical device safety
IEC 60601-1 basic safety and essential performance; EMC, alarm, usability and environmental requirements through the collateral standards.
Sterilisation validation
Validation of sterilisation processes by ethylene oxide, radiation or moist heat; bioburden and sterility assurance level studies.
Packaging
Integrity of the sterile barrier system, seal strength, distribution simulation and shelf-life studies.
Microbiological tests
Bioburden determination, sterility testing, bacterial endotoxin and, where required, carrier validation studies.
Software and usability
IEC 62304 life cycle evidence and use-error focused evaluation under IEC 62366.

Commonly confused in this field

Cytotoxicity alone is not evidence of biocompatibility; the required set of endpoints is determined and justified according to ISO 10993-1.
An ISO 13485 certificate does not confer CE marking; classification under the MDR, the technical file and the notified body process run separately.
Accelerated ageing does not replace real-time ageing; a shelf life claim is supported by real-time data.
A change of material (supplier, pigment, sterilisation method) may require the biological evaluation to be repeated; it is not a silent change.
An assessment made without the collateral and particular standards for IEC 60601-1 is incomplete; which -1-x and -2-x standards were applied must appear in the report.
In vitro diagnostic devices fall under the IVDR rather than the MDR, and laboratory equipment is often on the IEC 61010-1 side.

Which decisions these results support

MDR/IVDR technical file and notified body assessment
Completing the biological evaluation plan
Sterilisation and packaging validation
Determining shelf life and storage conditions
Determining the scope of reassessment after a design change

Related Tests

Frequently Asked Questions About Sterility — ISO 11737-2

Must sterility testing be performed on every batch?

The common approach for medical devices is parametric release: the process is validated and process parameters are monitored on every batch. Sterility testing is primarily used in validation and revalidation studies.

How does it relate to bioburden analysis?

Bioburden analysis under ISO 11737-1 determines the microbial load on the product before sterilisation. The sterilisation dose is calculated based on this load; the sterility test shows the process eliminates this load.