Deep Vein Thrombosis

Deep vein thrombosis (DVT) is the formation of a blood clot in a deep vein, most commonly in the legs, thigh, or pelvis. If the superficial veins (the veins close to the surface) developed a thrombus, the condition is called thrombophlebitis. The most common life-threatening concern with DVT is the potential for a clot to detach, travel through the inferior vena cava (IVC) to the right side of the heart and become stuck in pulmonary arteries that supply blood to the lungs, causing a serious medical condition called a pulmonary embolism (PE). Both DVT and PE are considered to be part of the same overall disease process, which is called venous thromboembolism (VTE). VTE can occur as an isolated DVT or as PE with or without DVT. The most frequent long-term complication is post-thrombotic syndrome (PTS), which can cause pain, swelling, a sensation of heaviness, itching, and in severe cases, venous ulcers.

B-Mode image of the left common femoral vein showing a thrombus lodged inside its lumen (arrow).

Do you feel pain or tenderness and have swelling, warmth, dilation of surface veins, and redness or discoloration of the legs, thigh, or pelvis? That may be deep vein thrombosis, which is the formation of a blood clot in a deep vein. Do you know that some DVT patients have no symptoms? Yes, signs and symptoms alone are not sufficiently sensitive or specific to make a diagnosis, but when considered in conjunction with pre-test probability, can help you and the referring physician to determine the likelihood of DVT. You may not know that in most suspected cases, DVT is ruled out after evaluation, and symptoms are more often due to other causes that mimic DVT but it is not, such as a ruptured cyst that is called Baker’s cyst located at the back of your knee joint, infection or inflammation of your skin known as cellulitis, blood collection called hematoma, obstruction of your leg lymph vessels called lymphedema, and presence of varicose veins. Other causes include tumors, venous or arterial dilatation known as aneurysms, and connective tissue problems.

If you have trauma to a leg, sitting still for a long time (immobilization), and/or you have an underlying blood disorder (coagulopathy) can make you more likely to develop a DVT. Some medicines and disorders that increase your risk for blood clots can also lead to DVTs. The mechanism of clot formation typically involves some combination of decreased blood flow rate, increased tendency to clot, and injury to the blood vessel wall. You would need to see your physician if you have risk factors that increase your chances of developing DVT such as recent surgery, older age, active cancer, obesity, personal history and family history of VTE, trauma, injuries, lack of movement, hormonal birth control, pregnancy and the period following birth, genetic components, and a few blood disorder syndromes.

Color flow imaging showing blood flow in the popliteal vein (blue) and popliteal artery (red).

When you visit your physician, he or she will able to evaluate you by applying a clinical probability assessment, which might determine whether you are “likely” or “unlikely” to have DVT. In those unlikely to have DVT, a diagnosis is excluded by a negative D-dimer blood test. In people with likely DVT, ultrasound is the standard imaging used to confirm or exclude a diagnosis. The sonographer will put ultrasound gel on the area and apply gentle probe pressure along the whole of your lower limb starting from the groin region to the ankle level. Ultrasound is the standard diagnostic method because it is safe, inexpensive, consumes a short amount of time, and is highly sensitive for detecting an initial DVT. You will be considered positive for DVT when the vein walls of normally compressible veins do not collapse under gentle ultrasound probe pressure. Moreover, the sonographer might apply color flow Doppler to further characterize the clot and he or she can use Doppler ultrasound to further assess the non-compressible pelvic veins. Please keep in mind that cross-sectional imaging using computed tomography venography (CTV) and magnetic resonance venography (MRV) are also diagnostic possibilities. The gold standard for judging imaging methods is contrast venography, which involves injecting a peripheral vein of the affected limb with a contrast agent and taking X-rays to reveal whether the venous supply has been obstructed. Because of its cost, invasiveness, limited availability, and other limitations, this test is rarely performed nowadays.

You would need to see your physician if you are confirmed to have DVT to seek treatment and prevention and resume normal life. Treatment includes medicines to ease pain and inflammation, break up clots, and keep new clots from forming. Keeping the affected area raised and applying moist heat can also help. If you are taking a long car ride or flight, take a break, walk or stretch your legs, and drink plenty of liquids. Prevention of VTE for the general population includes avoiding obesity and maintaining an active lifestyle.

Dr Akram Asbeutah

Dr. Akram Asbeutah, PhD, DMU-ASUM, ASAR, ASA, AIUM, SVU, AIR, ASRT, RT(R) ARRT, is a Clinical Associate Professor in the Department of Radiologic Sciences at the Faculty of Allied Health Sciences, Kuwait University & Monash University-Melbourne, Australia.

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