Tianjin Huanhu Hospital 1 article published in JoVE Medicine Determination of the Procoagulant Activity of Extracellular Vesicle (EV) Using EV-Activated Clotting Time (EV-ACT) Yalong Gao1,2,3, Kaiji Li1,2, Qiong Qin4, Jianning Zhang1,2, Li Liu1 1Key Laboratory of Post-Neurotrauma Neurorepair and Regeneration in Central Nervous System, Ministry of Education and Tianjin Neurological Institute, Tianjin Medical University General Hospital, 2Department of Neurosurgery, Tianjin Medical University General Hospital, 3Department of Neurosurgery, Tianjin Huanhu Hospital, 4Department of Medical Oncology, Tianjin Medical University General Hospital This protocol investigates the use of extracellular vesicle (EV)-rich plasma as an indicator of the coagulative ability of EV. EV-rich plasma is obtained through a process of differential centrifugation and subsequent recalcification.