Deep Vein Thrombosis (DVT)
The most common presentations of venous thrombosis are DVT of the leg(s) and pulmonary embolism, which is the end-result of DVT. Any thrombus in the venous circulation can separate from its thrombotic bed within the venous wall lining and migrate with the venous circulation to the right side of the heart where it is then propelled along with the deoxygenated blood to the lung vasculature, obstructing it and thereby preventing adequate ventilation. Because of these processes, DVT is a life-threatening condition and pulmonary embolism can be a life-ending condition.
DVT risk is increased, according to the theory of its genesis, with a triad of conditions:
- Alterations in blood flow (“stasis”)
- Endothelial injury (damage to the innermost wall layer)
- Inherited (congenital) or acquired (estrogen or pregnancy, trauma, surgery, malignancy) hypercoagulable states
Although superficial thrombosis is considered a less severe disorder than DVT, there is evidence that those with varicose veins have a fivefold increase in DVT risk and twice the pulmonary embolism risk than those without them.
Confirmation of chronic venous disease can be made by ultrasound to identify venous reflux (reversed flow). This is the first condition in the triad of conditions cited above.
The Doppler technology in the combined ultrasound procedure (combined with B mode ultrasound as “duplex ultrasound”) reflects sound waves off of red blood cells and thereby renders an image that indicates motion or the lack thereof. The B (brightness) mode of ultrasound, the other component, renders an image based on differences in tissue densities. As such, thrombi can be easily identified in accessible areas like the legs or arms.
Although duplex ultrasound has largely replaced more invasive investigations via CT and MRI venography (invasive due to contrast media used), these procedures are still important adjuncts when diagnosis needs further confirmation or a suspected thrombosis is in an ultrasound-inaccessible area.