How sterility is covered by the MDR

Sterile medical devices are vital for patient safety. Any contamination – whether microbial or particulate – can introduce significant clinical risks. As a result, sterility is a central component of the MDR, and covered extensively by the General Safety and Performance Requirements (GSPRs). These requirements demand both technical proof of sterility and robust processes to ensure consistency and device safety over time.

When sterility is involved, the need for strong regulatory oversight increases. For example, while Class I devices do not typically require external pre-market assessment and approval, this changes the moment a device takes on sterile form. If a Class I product is marketed as sterile, it falls under Class I sterile (Is) which mandates Notified Body involvement. 

For sterile Class IIa, IIb, and III devices, sterilization becomes an additional focus of the standard conformity assessment. In all cases, manufacturers must provide comprehensive documentation showing that sterility is achieved, validated, and maintained through the entire product lifecycle – from impact during production to point of use. 

Legal manufacturers must seek a Notified Body assessment specific to the sterilization process – even for low-risk sterile products.

Sterilization methods and MDR expectations

There is no one-size-fits-all approach to sterilization. As a manufacturer, you must evaluate your individual product’s material, function, and intended use before selecting a suitable sterilization method. Choosing the right method isn’t just a technical decision – it’s intrinsic to the design. 

The most commonly used methods are:

• Ethylene Oxide (ETO): Highly effective for complex and heat-sensitive products, but raises safety concerns due to residual toxicity. 
• Radiation (Gamma or Electron Beam): Quick and scalable, but may degrade polymers and electronics.
• Steam: Safe and well-established, but unsuitable for products sensitive to heat or moisture.

Each method comes with a suite of harmonized standards under the MDR, including EN ISO 11135 for ETO, EN ISO 11137 for radiation, and EN ISO 17665 for steam. These standards guide you through required validation protocols and documentation.

The MDR expects you to evaluate sterilization compatibility at the earliest opportunity in the design stage. You must also document how the method was selected based on product needs and risk profiles. 

Packaging and sterile barrier systems

Sterility is only as good as the packaging that protects it. In this respect, MDR expectations are clear: labeling must reflect the sterilization method, include the date of expiry, and warn users not to use the device if the packaging is damaged.

Even if you use off-the-shelf packaging materials, you must validate those materials as part of your own processes. Your chosen sterile barrier system (SBS) must maintain sterility during handling, storage, and transportation. Validation requires:

• Mechanical testing such as vibration and drop tests
• Seal integrity testing including dye penetration and bubble leak
• Accelerated and real-time aging studies to support expiry dates

Process validation and proof of sterility

Process validation is the cornerstone of sterility compliance. The reason is simple: it’s not possible to confirm sterility on every finished device without compromising it. You have to rely on a three-step validation model known as IQ/OQ/PQ:

1. Installation Qualification (IQ) – Ensures all equipment (such as a sterilizer or a clean room) is installed correctly and functioning as intended.
2. Operational Qualification (OQ) – Verifies that the system consistently operates within defined parameters like temperature, humidity, and exposure time.
3. Performance Qualification (PQ) – Demonstrates that the sterilization process produces a consistently sterile output through sample testing and bio-burden analysis.

Validation is not a ‘one-time-only’ activity. Through the EU MDR, the regulators expect ongoing monitoring and periodic revalidation. The frequency of this is risk-based and defined in your Quality Management System (QMS).

Documentation and standards for sterility

Paperwork plays a central role in MDR compliance. You must maintain accurate records detailing the method, process parameters, equipment validation, packaging validation, and ongoing monitoring. Relevant standards include:

• EN ISO 11135 – Sterilization By Ethylene Oxide
• EN ISO 11137 – Radiation Sterilization
• EN ISO 17665 – Steam Sterilization
• ISO 14937 – General Sterilization Requirements
• EN ISO 11607-1/-2 – Packaging For Terminally Sterilized Medical Devices
• EN 556-1 – Requirements For Labeling As ‘Sterile’

Notified Bodies may audit sterilization files and, for high-risk products, inspect critical subcontractors – particularly if sterilization is outsourced. As with other supply-chain related regulation, the legal manufacturer has a responsibility to also ensure external partners adhere to MDR requirements.

Resterilization, reuse, and single-use devices

Manufacturers must clearly define whether a product is single-use or reusable. If a device is intended for reuse, validated resterilization instructions must be included with the product. That’s because under the MDR, when a third party reprocesses a single-use device, they assume the role of the legal manufacturer and must meet all associated obligations.

Residual contaminants – even from dead microbes – can still trigger allergic or inflammatory reactions. This underscores the importance of cleaning before sterilization and differentiating between ‘clean’ and truly ‘sterile’ products.

Quality management systems and sterilization

Many manufacturers underestimate the complexity of aligning sterilization processes with the broader regulatory framework. Beyond choosing and validating a sterilization strategy and method, one of the greatest challenges lies in establishing a Quality Management System (QMS) that consistently meets MDR expectations – and in preparing the correct documentation for submission to your Notified Body.

A compliant QMS must fully integrate sterilization controls, including risk-based revalidation schedules, supplier oversight (especially for outsourced sterilization), and traceable process records. These elements must not only function in practice, but also be reflected clearly in your technical documentation and conformity assessment submissions.

Errors or omissions in documentation are among the most common reasons for delays or rejections during Notified Body review. Especially for small and mid-sized manufacturers, engaging a regulatory consultant can provide clarity, structure, and confidence throughout the conformity assessment process. Regulatory consultants – like those at Dawn Technology – can provide critical support in this area, helping to:

• Identify and fill gaps in your sterilization-related QMS. 
• Define a pragmatic but effective sterilization strategy for your product portfolio:
  
  • This includes a justification for your worst case product and a description of the best methods to test your challenge device and achieve the required Sterility Assurance Level (SAL)
  • Placement strategy for your Biological Indicator
  • Prepare and organize documentation to meet Notified Body expectations.
• Interpret and apply harmonized standards in a practical, compliant way.
• Advise on timelines and regulatory strategy to avoid costly delays.

We can help ease your regulatory burden

Sterility under the MDR isn’t just about eliminating microbes – it’s about proving, documenting, and maintaining a validated process that ensures patient safety.

With the right preparation, clear documentation, and sound design principles, you can confidently meet regulatory expectations and bring safe, sterile products to the EU market. 

If you’re navigating sterilization requirements under the MDR and need strategic or technical support, don’t hesitate to speak to one of our regulatory consultants.

Could you use an expert in MDR compliance? We can help! Reach out to one of our team today. Get in touch