 Deep vein thrombosis DVT of the arm, officially called upper extremity DVT is a rare disorder and accounts for up to 1-4 of all cases of deep vein thrombosis. In case of a thrombosis, there is a blood clot in one of the veins, which should be treated with blood thinners anticoagulants. The aim of the present study is to see whether it is safe to use a combination of tests for the diagnosis of arm thrombosis. In all patients, we will use a clinical decision rule clinical judgement and a laboratory test D-dimer testing, in most patients also an ultrasound of the arm will be done. The combination of these tests was found to be safe and effective in patients with thrombosis of the legs. 