PROS1 and thrombophilia: IJVthr is often a complication of head and neck, local skin, and throat infections [23,24,46,47,48], surgery [49,50,51], trauma [17], local or distant malignancy [3,11,25,51,52], central venous catheter placement [43,44,45], polycythemia vera [37,53,54,55], intravenous drug abuse [56,57], neck massage [12], ovarian hyperstimulation syndrome [58,59,60,61], hypercoagulable state secondary to factor V Leiden, protein C, protein S, anti-phospholipid syndrome, anti-thrombin III deficiency [13,14,36,62,63,64,65], or it can be a primary process [1,3,4,5].