 Platelet Function Tests Cone-and-Platelet Analyzer This technology has been described elsewhere 40. Briefly, 200 μL of citrated blood was placed in a polystyrene well and subjected to a shear rate of 1300 sec-1 using a rotating conical disk for 2 minutes. The well was washed and stained by May-Gruenwald stain. Platelet adhesion was evaluated as the percentage of total area covered with platelets designated as surface coverage and aggregation as the mean size of the surface-bound aggregates designated as average size μm2 by use of an image analysis system Galai. 