Experimental approach to rouleau formation. Comparison of three methods

From a clinical point of view, the approach to erythrocyte aggregate or rouleau formation and cohesion is undeniably of great interest. A large number of methods have been suggested for studying this parameter such as: back-scattering of light, nephelometry, ultrasound, etc... In this paper the authors have compared three methods to approach rouleau formation: direct observation of rouleau formation (rheoscope); 'erythrocyte aggregometer': with this technique, the light transmitted by the sample is integrated over a period of time and provides an index (IA); laser reflectometer based on studying the light that is back-scattered by the blood sheared in the gap of a viscometer. The results show that the indexes measured by both reflexion and transmission vary according to hematocrit and reach a maximum value at hematocrit levels of between 30 and 40%. In contrast, observation using the rheoscope did not provide qualitative evidence of this phenomenon.