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. PTT addresses the coagulation category and is typically called for in external communicating devices with circulating-blood contact and in blood-contacting implants.
When to run it
After cytotoxicity, on finished, sterilised samples with the material, surface finish and process locked, and in one campaign with the other hemocompatibility tests your device category calls for.
What a pass tells you
That clotting time after exposure to the device was not significantly shortened or prolonged relative to the concurrent negative control, with the positive control performing as expected. A shortened PTT indicates activation of the intrinsic pathway; a prolonged one indicates interference with it.
What it does not tell you
Coagulation is one category of blood interaction. A clear PTT says nothing about hemolysis, complement, platelet consumption or thrombus formation under flow, each of which has its own test, and nothing outside hemocompatibility.
Method
Testing per ISO 10993-4:2017. The device, or an extract where the geometry requires it, is incubated with human platelet-poor plasma alongside negative and positive controls. Partial thromboplastin time is then determined on a coagulation analyser and compared with the control values. 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
Complete hemolysis (GRK-4006-03), complement activation and platelet and leukocyte counts where the device category calls for them, the blood loop assay where the device meets blood in motion, and cytotoxicity as the baseline screen.
