The present subject matter concerns methods for determining platelet medicated clot formation. Specifically, the subject matter provides a method for determining platelet-medicated clot formation in a blood sample. The method may include obtaining sample of blood, and optionally mixing same with an anti-coagulant in an amount effective to inhibit clot formation. Additionally, the method may include mixing the sample in a vessel with a minute amount of an initiator to obtain a mixed sample, the amount being effective to initiate coagulation. The method may further include rotating the mixed sample inside the vessel, whereby shear forces are developed at the surface of the vessel in a manner and for a time sufficient to allow adhesion of platelets at the surface of the vessel. In addition, the method may include determining clot formation at the surface of the adherent platelets.