ULDVT accounts for approximately 10% of all Deep Vein Thromboses (DVT) with an incidence of 0.16 per 1000 in the general population. The majority (60%) of ULDVT are provoked by the use of a central venous catheter (CVC), including peripherally inserted central venous catheters (PICC) and pacemakers. Occasionally ULDVT will be the first presentation of malignancy, in particular a mediastinal mass causing Superior Vena Cava Obstruction (SVCO).
Rarely, an ULDVT may be related to Venous Thoracic Outlet Syndrome (TOS) (also known as effort thrombosis or Paget-Schroetter syndrome) where axillary/subclavian vein thrombosis occurs, usually in a younger patient, in the context of strenuous and repeated activity of the upper limb. This may just relate to muscular build but there can be underlying anatomical causes such as first rib and anterior scalene muscle anomalies.