The examination begins with the patient in a supine position to establish the resting baseline. Once images confirm the arteries and veins to be technically normal, the patient is placed in a seated position. Bilateral examination is performed, unless specifically indicated by the referring physician. Several groups have found that a significant number of patients experience venous compression of the contralateral side warranting a bilateral examination [19].

Starting on the symptomatic side with arms in a neutral position, the subclavian vein and axillary vein are evaluated for evidence of intraluminal obstruction or narrowing secondary to extrinsic compression. This starts with the ultrasound probe placed transversely, slightly medial and just superior to the medial portion of the clavicle for complete evaluation of the proximal subclavian vein. In B-mode, the subclavian vein is examined with and without compression to assess for the presence of occlusive or nonocclusive thrombosis. Spectral Doppler analysis is then utilized in order to obtain waveform and velocity measurements during quiet respiration. The transducer is then repositioned beneath the clavicle and directed medially to identify and evaluate the mid to distal portion of the subclavian vein as it travels beneath the clavicle in the costoclavicular space [20]. Attention is directed to the location of the subclavian vein as it relates to the subclavian artery. Anatomically, the subclavian vein normally lies superficial and caudal to the subclavian artery and courses with the artery when imaged in the transverse plane [21]. Any deviation in expected anatomic location or inability to identify the subclavian vein should be documented. Identifying the location of the subclavian vein relative to the subclavian artery is important in differentiating the main vein from enlarged venous collaterals in the subclavicular area. B-mode imaging with and without compression is performed to assess for the presence of occlusive or nonocclusive thrombus in the mid-distal subclavian vein. Color Doppler imaging is then utilized with the probe in the longitudinal plane to evaluate for color filling in the mid through distal subclavian vein. Any reduction or absence of color filling in the vein in this region is documented. Spectral Doppler analysis is utilized in order to obtain waveform and velocity measurements during quiet respiration in the distal region of the subclavian vein just proximal to the confluence with the cephalic vein. In regions of visualized narrowing, Doppler velocity measurements are acquired proximal to and within the region of narrowing.

Next, duplex ultrasound imaging is performed to evaluate the axillary vein. For consistency purposes within a lab, the axillary vein is defined as the vein lateral to the confluence of the cephalic and subclavian vein. The axillary vein lies medial and inferior to the axillary artery in its normal anatomic position. It is important to identify the location of the axillary vein in relationship to the axillary artery in transverse. This view is necessary in order to differentiate the axillary vein from the presence of any possible enlarged venous collaterals. The cephalic vein can be confused with the axillary vein in the clinical setting of axillary vein thrombosis [15]. Both B-mode and color Doppler imaging are performed with and without compression to assess for occlusive or nonocclusive thrombus of the axillary vein. Spectral Doppler analysis with angle correction is then utilized in order to obtain waveform and velocity measurements during quiet respiration in the axillary vein. Again, in regions of visualized narrowing, Doppler velocity measurements will be acquired proximal to and within the region of narrowing. Representative axillary vein pulse Doppler waveforms are then obtained during provocative maneuvers with arms elevated to 90 and 180°. The transducer is positioned beneath the clavicle and directed medially to visualize the distal subclavian and proximal axillary vein in the resting position. Next, the patient is asked to slowly abduct their arm while visualization of the vessel is maintained. Once the patient has fully abducted their arm, a spectral Doppler waveform and velocity are obtained in these locations in both veins. B-mode and color Doppler imaging are performed as well to assess for any stricture of these vessels (Fig. 43.2).

Any variation to the above protocol must be reflected in the exam report. If evidence of venous obstruction is identified, a complete upper extremity venous evaluation should be performed to define the severity and extent of venous obstruction. The use of various probes is encouraged, as needed, to improve the diagnostic value of the exam. It is the responsibility of the performing technologist to clearly document any technical limitations of the exam if the defined examination protocol cannot be completed. Additional images with color Doppler alone and/or power Doppler may be used to help demonstrate regions of concern or better display abnormalities.

For patients who are suspected to have an arterial component of TOS by means of physical and clinical examinations, a scanning technique similar to the venous TOS protocol is employed. As with venous TOS examination, the anatomic location, vessel diameters, and course of the upper extremity vessels should be carefully noted and documented. Examination in B-mode and color Doppler imaging of the subclavian artery and axillary artery is done to assess for nonocclusive or occlusive thrombus, evidence of stenosis, dilation, or aneurysm formation (Fig. 43.3). Spectral Doppler analysis and velocity measurements are documented in the subclavian and axillary artery. Attention is directed toward assessing for any change of velocities in these vessels with provocative maneuvers, including arm elevation to 90 and 180°. These measurements may be repeated to confirm accuracy. Additional B-mode and color/power Doppler images and cine clips can be obtained to further illustrate the findings. The transducer is positioned once again beneath the clavicle and directed medially to visualize the distal subclavian and proximal axillary artery in the resting position. As with provocative evaluation of the veins, the patient is asked to slowly abduct the arm while visualization of the artery is maintained. With the arm fully abducted, spectral Doppler waveform and velocity are obtained, along with B-mode and color Doppler imaging to assess for stricture.