Veins can be easily distinguished from arteries by their compressibility (Figure 10.24). For this reason, the examiner should use only light pressure when first attempting to identify a vein. Blood flow can be seen through veins with color or power Doppler. Veins lack the constant flow with Doppler imaging, which is characteristic of arteries. Flow can be accentuated with compression and decompression of a vein (Figure 10.25). Similar to arteries, veins should be assessed in both short and long axis (Figure 10.26). The long­axis view is generally more reliable when assessing the compressibility of a vein (Figure 10.27). Lack of normal compressibility suggests the likelihood of venous thrombosis. The loss of anechoic appearance and loss of flow in the vein are additional suggestions of thrombosis (Figure 10.28). Because of the implications, it should also be determined whether the thrombo­sis is within a deep or superficial vein (Figure 10.29). The patient should be referred for a conventional venous Doppler evaluation if deep venous thrombosis is suspected during a musculoskeletal evaluation, particularly if the practitioner is not experienced in the diagnosis of vascular conditions.