EDITORIAL Bringing flow into haemostasis diagnostics

Virchow first defined the importance of blood flow in haemo-stasis and thrombosis, but first received acknowledgement 100 years after his publication in 1856.1 Blood is a non-Newtonian fluid and its viscosity is dependent on the flow, flow velocity, type of flow (laminar or non-laminar), concentra-tion of different types of blood cells, plasma protein size/ concentration, and temperature.2 3 At higher flow rates, blood behaves as a Newtonian fluid with reduced viscosity. Flow trans-fers energy to the blood and the vascular wall and this is called shear stress. Shear rate is defined as the rate at which adjacent layers of fluid move with respect to each other. Shear rate/stress differs in the venous and arterial circulation, but also increases when the vascular lumen decreases, naturally when blood moves peripherally and with pathological constrictions like thrombus, plaques, mechanical valves, stents, and vascula