Emergency Ultrasound > Extremity Swelling > Upper Extremity DVT
Extremity Swelling - Upper Extremity DVT
Upper-extremity DVT now accounts for about 8% of all cases of DVT. Subclavian vein (SCV) clot is usually associated with arm swelling. Jugular venous (JV) clot is often asymptomatic.
Diagram of venous drainage of upper extremity: A-Medial cubital vein; B-Basilic vein; C-Cephalic vein; D-Brachial vein; E-Axillary vein; F-Subclavian vein; G-External jugular vein; H-Internal jugular vein; I-Brachiocephalic vein; J-Superior vena cava.
Patient position: Arm is abducted about 45¡ to 90¡ from patient. The head is elevated a little, or put patient flat or even in Trendelenburg position to distend the veins.
Use a linear transducer (5 MHz for average patient, 3.5 MHz may be needed for obese patients, 7.5 MHz if thin). Use compression on the axillary, brachial, and jugular veins just as you would compress lower extremity veins. The SCV cannot be directly compressed and requires more careful examination. Generally the SCV is best evaluated from the infraclavicular approach. The central portion can be usually imaged from the supraclavicular approach.
First just look at the SCV. Note changes in size with respiration and sniff maneuver. A normal SCV should collapse at least 60%. With complete obstruction, there is no response to these respiratory maneuvers and the vein is often asymmetrically dilated. Look at the opposite presumed normal side.
Compare bilateral waveforms. Look for absent or very decreased flow in the symptomatic side compared to the normal side. Asymmetry indicates a problem. Unlike the lower extremities there may be phasic flow in the SCV even with a completely occluding thrombus.
Look for filling defects, which could suggest a thrombus. Slow flow can indicate a possible thrombus in the BCV or SCV especially if there is slow flow compared with the opposite side. Comparison will also help you with the settings if you are having trouble getting color on the abnormal side. Look from both infra- and supraclavicular approaches.
Figure A. Transverse image of internal jugular vein (red arrowheads) and carotid artery (red arrow). Figure B. Transverse image with transducer compression applied shows the compressibility of internal jugular vein (red arrowheads) while the carotid artery (red arrow) maintains its shape.
Sonographic Findings of DVT:
1) Lack of complete compressibility of vein.
2) Visualization of intraluminal thrombus with complete or partial obstruction of the vein lumen.
Longitudinal image of the subclavian shows enlargement and non-compressibility with the transducer (red arrowheads) and an intraluminal thrombus (red arrow).
3) Distention of the vein compared to the adjacent artery.
Deep Vein Thrombosis-Upper Extremity. Color Doppler image of the subclavian vein shows that the lumen is distended with hypoechoic thrombus (red arrows). Very minimal blood flow in the vein is evident. Flow is present in an adjacent artery (red arrowhead).
4) Abnormal venous Doppler signals, i.e. continuous nonphasic flow, reduced or absent flow with distal augmentation, or no obtainable signal.
Duplex Doppler demonstrating non-phasic flow in a peripheral vein with thrombosis.
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