All examinations were performed on the axillary vein of the affected side with the patient in supine position and the arms kept alongside the body. The diameter and flow velocity of the axillary vein in the affected upper limb was measured using a Xario US device (Toshiba Medical Systems, Tokyo, Japan) with a 7.5-MHz linear probe. Accurate identification of the vein was confirmed by a positive compressive pressure test and by assessing venous flow via color Doppler imaging.