 Introduction/Background Soft-tissue swelling is usually due to an alteration in capillary hemodynamics causing motion of fluid from the vascular spaces into the interstitium, secondary to either increased plasma volume (eg, heart failure, pregnancy), increased capillary hydrostatic pressure (eg, superior vena cava syndrome, deep vein thrombosis [DVT], reflex sympathetic dystrophy, trauma), decreased capillary oncotic pressure (eg, cirrhosis, malnutrition), or increased capillary permeability (eg, allergic reactions, infection, inflammation). It can also be due to lymphatic obstruction (eg, lymphedema, malignancy). The etiology of acute isolated upper-extremity swelling is often apparent from the clinical history (eg, trauma, infection, inflammatory arthritis) or can be suspected when risk factors are present (eg, venous thrombosis due to a venous catheter). Upper-extremity DVT (UEDVT) accounts for up to 10% of all diagnosed DVTs [1,2]. It can be primary in a third of cases due to venous thoracic outlet syndrome [3] (ie, effort-related thrombosis/Paget-Schroetter syndrome) and occasionally is idiopathic. Secondary UEDVT is far more common. Indwelling venous devices, such as catheters, pacemakers, and defibrillators, put patients at the highest risk of thrombus [1,4-10]. Other risk factors include advanced age, previous thrombophlebitis, postoperative state, hypercoagulability [4,11,12], heart failure [4], cancer [7,9-14], right-heart procedures, intensive care unit admissions [1,10], trauma, and extrinsic compression. Patients with certain abnormally elevated coagulation factors were demonstrated to be at increased risk of UEDVT [15]. Although many of the same risk factors for lower-extremity DVT also increase the risk for UEDVT, research is helping to elucidate certain variables unique to thrombi in the upper extremity [1,16].
Suspected Upper Extremity Deep Vein Thrombosis.  Introduction/Background Soft-tissue swelling is usually due to an alteration in capillary hemodynamics causing motion of fluid from the vascular spaces into the interstitium, secondary to either increased plasma volume (eg, heart failure, pregnancy), increased capillary hydrostatic pressure (eg, superior vena cava syndrome, deep vein thrombosis [DVT], reflex sympathetic dystrophy, trauma), decreased capillary oncotic pressure (eg, cirrhosis, malnutrition), or increased capillary permeability (eg, allergic reactions, infection, inflammation). It can also be due to lymphatic obstruction (eg, lymphedema, malignancy). The etiology of acute isolated upper-extremity swelling is often apparent from the clinical history (eg, trauma, infection, inflammatory arthritis) or can be suspected when risk factors are present (eg, venous thrombosis due to a venous catheter). Upper-extremity DVT (UEDVT) accounts for up to 10% of all diagnosed DVTs [1,2]. It can be primary in a third of cases due to venous thoracic outlet syndrome [3] (ie, effort-related thrombosis/Paget-Schroetter syndrome) and occasionally is idiopathic. Secondary UEDVT is far more common. Indwelling venous devices, such as catheters, pacemakers, and defibrillators, put patients at the highest risk of thrombus [1,4-10]. Other risk factors include advanced age, previous thrombophlebitis, postoperative state, hypercoagulability [4,11,12], heart failure [4], cancer [7,9-14], right-heart procedures, intensive care unit admissions [1,10], trauma, and extrinsic compression. Patients with certain abnormally elevated coagulation factors were demonstrated to be at increased risk of UEDVT [15]. Although many of the same risk factors for lower-extremity DVT also increase the risk for UEDVT, research is helping to elucidate certain variables unique to thrombi in the upper extremity [1,16].