When this test applies
Required wherever the device contacts circulating blood, under ISO 10993-1:2025. ISO 10993-4 does not prescribe one test — it sets out which blood-interaction categories apply to which device type, and hemolysis is one of them. The indirect arm answers the question about leachables specifically, as distinct from the mechanical and surface effects the direct-contact arm captures.
When to run it
After cytotoxicity, and once the material set and surface finish are settled. Blood interaction is sensitive to surface topography and to processing residues, so running it on a material you still intend to change tends to buy a result you have to repeat.
What a pass tells you
That the hemolytic index falls in the 0 to 2% band, which ISO 10993-4 with ASTM F756 classes as non-hemolytic. Above 2% up to 5% is slightly hemolytic and above 5% is hemolytic; only the non-hemolytic band is a pass.
What it does not tell you
It tests the extract, not the surface. A device whose leachables are benign can still damage cells mechanically on direct contact, which is why the direct arm exists. ISO 10993-4 may call for several of the blood-interaction tests together, and a pass on one says nothing about the others.
Method
Testing per ISO 10993-4:2017 with ASTM F756. A single extract is prepared for indirect contact and exposed to rabbit blood, and the hemolytic index is determined against concurrent positive and negative controls. Extraction ratios follow 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. The laboratory is ISO/IEC 17025 accredited and GLP certified, and the report is issued under Groenakker cover, in Groenakker’s report template or in your document template on request at no extra cost.
Usually ordered alongside
The direct-contact arm of hemolysis, and the other ISO 10993-4 categories your device type calls for. Cytotoxicity is the baseline screen.
