When Does a Medical Device Need ISO 10993 Biocompatibility Testing?

Medical devices that come into contact with a patient’s body require biocompatibility testing. This step isn’t optional. It’s a foundational part of bringing a safe product to market in the U.S., the EU, and most other regions worldwide.

Understanding when ISO 10993 biocompatibility testing is required is essential for ensuring that your medical device meets regulatory standards and is safe for patient use. ISO 10993 testing requirements depend on two simple factors: how your device contacts the body and for how long. When you know the answers to these two questions, you can map out a clear testing strategy instead of guessing at what regulators expect.

Key Takeaways

• ISO 10993 biocompatibility testing applies to nearly all new medical devices that contact the body, whether directly or indirectly.
• The type of body contact and the contact duration determine which specific tests apply to your device.
• Cytotoxicity, sensitization, and irritation testing (known as the “Big Three”) apply to almost all devices that come into contact with the body.
• Devices like implants that contact tissue more deeply or for longer periods of time require much more extensive testing, including hemocompatibility, genotoxicity, and systemic toxicity evaluations.
• Instead of treating these tests as an afterthought, it’s best to have a biological evaluation plan (BEP) to guide your testing strategy from the very beginning.

Which ISO 10993 Tests Typically Apply to Different Medical Devices?

The ISO 10993 series isn’t a single test. It’s a family of standards, each addressing a specific biological risk. Part 1 of the series lays the groundwork, requiring manufacturers to create a biological evaluation plan that documents the biological risks specific to a device and how those risks will be addressed.

From there, other parts of the standard apply based on your device’s characteristics. Here are a few examples:

• ISO 10993-5 (cytotoxicity) and ISO 10993-10 (sensitization) apply to nearly all new devices that make contact with the body directly or indirectly.
• ISO 10993-23 (irritation) also applies broadly to body-contacting devices. Together, these three tests are commonly referred to as the “Big Three” in biocompatibility testing.
• ISO 10993-18 (chemical characterization) applies to all new devices in direct or indirect body contact. It often informs whether additional testing like a toxicological risk assessment under ISO 10993-17 becomes necessary.
• ISO 10993-4 (hemocompatibility) applies specifically to devices that contact blood.
• ISO 10993-3 (genotoxicity) and ISO 10993-11 (systemic toxicity) apply to devices with prolonged or long-term tissue contact.

Determining the right combination of tests can be tricky, and it all depends entirely on your specific device. This is where working with experienced ISO 10993 compliance consultants can save significant time. Rather than testing for every possible endpoint, a well-built BEP identifies precisely which risks apply to your product.

How Body Contact and Contact Duration Shape the Biocompatibility Testing Strategy

Two variables drive nearly every decision in a biocompatibility testing strategy: the nature of body contact and how long that contact lasts.

Typically, body contact falls into one of three categories. The first includes devices that only come into contact with the surface of the body like intact skin or mucosal membranes. The second category includes external devices that communicate, like those connected to the blood path. The third includes implant devices that directly contact tissue, bone, or blood.

Duration falls into three preset windows:

• Limited: 24 hours or less
• Prolonged: More than 24 hours, up to 30 days
• Long-term: More than 30 days

A device that touches only intact skin for a few hours has a much lighter testing burden than one implanted in tissue for months. As contact becomes deeper or longer, more biological systems come into play, and testing must account for that increased risk.

Test methods also vary by market. ISO 10993-1:2025 encourages the use of non-animal methods such as chemical analysis and in vitro assays when they produce results as reliable as in vivo testing. In the EU, in vitro tests are often sufficient for lower-risk devices. However, in the U.S., the FDA still commonly requires in vivo testing for endpoints like irritation and sensitization. The target market and the device design both impact the final testing plan.

What Biocompatibility Testing May Be Needed for a Skin-Contacting Device

Devices that only touch intact skin, like an elastic bandage or a wearable sensor housing, sit at the lower end of the testing spectrum. For a device like this intended for the U.S. market, a typical strategy might include:

1. Chemical characterization using both polar and non-polar solvents to identify extractables under exaggerated conditions, followed by a toxicological risk assessment aligned with FDA’s guidance on ISO 10993-1.
2. Cytotoxicity testing on device extracts using a quantitative method like the neutral red uptake (NRU) test, as required under ISO 10993-5.
3. Sensitization testing using a combination of non-animal methods, such as the direct peptide reactivity assay (DPRA), KeratinoSens, and h-CLAT, to address multiple stages of the sensitization pathway. The FDA may also still request a guinea pig maximization test (GPMT) or Buehler test, depending on the device and submission type.
4. Irritation testing using a reconstructed human epidermis (RhE) model, although the FDA may require an in vivo intracutaneous reactivity study in addition to or instead of in vitro methods for certain device types.
5. Intracutaneous reactivity testing using an in vivo rabbit model, which the FDA commonly requests for skin-contacting devices even when in vitro irritation data is available.

Unlike the EU, the FDA has not fully transitioned away from animal-based endpoints for irritation and sensitization. Non-animal methods can support your submission, but they typically need to be paired with strong scientific justification and, in some cases, additional in vivo data. Working with an ISO 10993 compliance specialist early in your design process helps confirm which methods the FDA will accept for your specific device and submission pathway.

What Biocompatibility Testing May Be Needed for an Implant

Understandably, implants face a much more rigorous path for biocompatibility testing. For example, a typical test sequence for a knee implant intended for long-term use in direct contact with bone and tissue might look like this:

1. Chemical characterization using exhaustive extraction with polar, semi-polar, and non-polar solvents to identify extractables and degradation products, followed by a toxicological risk assessment.
2. Cytotoxicity testing using the NRU method on device extracts.
3. Sensitization testing using the GPMT, the FDA’s recommended method for devices that contact deep tissue.
4. Irritation and intracutaneous reactivity testing in rabbits, using intradermally injected device extracts.
5. Implantation and chronic systemic toxicity assessment, including histopathological evaluation of local tissue response and systemic effects.
6. Genotoxicity testing using a bacterial reverse mutation assay (Ames test) alongside a mouse lymphoma assay (MLA) to detect a broad range of genotoxins.

Every one of these steps addresses a specific biological risk introduced by long-term implantation. Skipping even one endpoint can delay your regulatory submission or worse, create a genuine safety concern.

Building a Biocompatibility Strategy That Works for Your Device

Every device is different, and the exact combination of tests your product needs depends on its materials, its design, and how patients will use it. A biological evaluation plan gives you a documented, defensible roadmap before testing begins. It also keeps you from scrambling to respond after a regulatory submission gets flagged.

If you’re building a new device and aren’t sure where your product falls on the body-contact and duration spectrum, that’s a good sign it’s time to bring in expert support. MedLaunch guides medical device developers through biocompatibility assessments and other regulatory requirements, turning what can feel overwhelming into a clear, step-by-step process. Schedule a consultation with our team to build a biocompatibility strategy suited to your specific device and target market.

Tags: biocompatibility testing, ISO 10993