When this test applies
ISO 10993-1:2025 flags hemocompatibility for every device that contacts circulating blood, directly or indirectly. ISO 10993-4:2017 breaks the endpoint into categories — thrombosis, coagulation, platelets, haematology and immunology (complement) — and selects tests by device category and contact duration. Hemolysis is the test ISO 10993-4 expects for essentially every blood-contacting device, and most reviewers expect both the direct and indirect arms, which is why this combined study is the usual order.
When to run it
After cytotoxicity, on finished, sterilised samples with the material, surface finish and process locked. It is quick relative to the rest of the hemocompatibility set, so run it early in that campaign.
What a pass tells you
That both arms fell in the non-hemolytic range: a hemolytic index of 0 to 2% under ASTM F756 for the device in direct contact and for its extract, with the positive control performing as expected. Over 2 up to 5% is slightly hemolytic and above 5% hemolytic.
What it does not tell you
Nothing about thrombosis, coagulation, platelets or complement — each is a separate ISO 10993-4 category with its own test — and nothing about blood under flow, which is the blood loop assay. Nor anything outside hemocompatibility.
Method
Testing per ISO 10993-4:2017 with ASTM F756. In the direct arm the device or a representative sample is incubated with diluted rabbit blood; in the indirect arm a single extract of the device is incubated with the same blood. Negative and positive controls run with both. Released haemoglobin is measured spectrophotometrically and expressed as a hemolytic index for each arm. Extraction ratio follows ISO 10993-12: 6 cm²/mL for material under 0.5 mm thick, 3 cm²/mL at 0.5 mm or thicker, or 0.1 to 0.2 g/mL where surface area is indeterminate.
Where it runs
This method is internationally sourced (OUS). The laboratory is ISO/IEC 17025 accredited and GLP certified, and the report is issued under Groenakker’s ISO 13485:2016 certified quality system, in Groenakker’s report template or in your document template on request at no extra cost.
Usually ordered alongside
Complement activation, platelet and leukocyte counts and PTT where the device category calls for them; the blood loop assay where the device meets blood in motion; and cytotoxicity as the baseline screen. A biological evaluation plan establishes which of these your device actually needs.
