How is DVT diagnosed?
If you have the symptoms of DVT, your doctor will perform a physical examinationand ask you about your medical history to determine if you are at risk for DVT. A blood test called the D-dimer test may also be used to quickly rule out DVT. If it is likely that your symptoms are caused by DVT, your doctor will order an imaging test to confirm and locate any blood clots.
The most common test used to diagnose DVT is a Doppler ultrasound of the leg. This fast, simple, painless test uses sound waves (like those used to view the fetus during pregnancy) to produce images of the veins. This test is very accurate at diagnosing clots higher in your legs, but may miss some clots in the calves. If an ultrasound is inconclusive, your doctor may ask you to come back for a repeat test in 3 to 7 days, or you may have additional tests to get a closer look at the veins. An additional venogram test may also be necessary if your ultrasound results were normal, but your doctor still suspects you have a clot, especially in the pelvis.
Venography is rarely used, but remains the gold standard test for the diagnosis of DVT. A dye is injected into a vein in the foot, which highlights the leg veins on an X-ray image as the blood is carried back to the heart. A blood clot will appear as an area inside the leg veins where the dye did not penetrate.
If you have the symptoms of severe PE, you may be treated immediately because the risk of delaying treatment for testing is too great. For those with less severe PE symptoms, you may have tests to rule out other causes of the symptoms (such as heart problems), including a chest X-ray and ECG. If the doctor thinks PE is likely, she or he will order a CT pulmonary angiogram, which uses a dye injected into a vein to visualize blood flow to the lungs on a CT scanner.
How is DVT treated?
The goal of DVT treatment is to prevent PE, stop the clot from growing, and prevent new clots from forming.
Blood thinning (anticoagulant) drugs are the main treatment for DVT. Blood thinnersdo not actually thin the blood, but make it less likely to clot, preventing existing clots from growing and new clots from forming. The most commonly used drugs are low molecular weight heparin (LMWH) or standard IV heparin. LMWH can be taken through an injection at home, but IV heparin requires that you remain in the hospital. Once your blood is thinned with LMWH or a heparin, you will begin taking warfarin for long-term blood thinning (usually taken for 3 to 12 months after you leave the hospital).
In most cases, enzymes in your blood will gradually break down the clot, allowing your body to reabsorb it. However, if you have a PE or a large DVT, you may also receive clot-busting drugs (such as tPA, which is also used to treat stroke) to speed up the breakdown of the clot. Clot-busting drugs carry a risk of excessive bleeding and are not usually necessary in women with smaller DVTs. More recently, doctors have begun treating some very severe blood clots by breaking them up with catheters (a long, thin tube inserted into your blood vessels through a small incision).
In less common cases, women who cannot take blood thinners, or who have had repeated DVTs or PEs even with treatment, may have a filter inserted into the vena cava, the large vein that takes blood from the body back into the heart. This filter does not prevent DVT, but it catches any blood clots that travel up from the legs, preventing them from getting to the lungs and causing a PE.
What is the prognosis of someone with DVT?
DVT rarely causes sudden death, and 96% of patients survive the initial event. In contrast, about 10% of patients with PE die within the first hour of symptoms, and a diagnosis of PE is often made only after death. Within one month about 6% of DVT patients and 12% of PE patients die.
After the first month, death in patients with a DVT or PE is rarely related to the initial event. Instead, the main concern is the risk of repeated blood clots or vein problems. Women who suffer a DVT or PE are more likely to have another in the future. However, there are steps you can take to risk reduce your risk of future problems:
People who suffer one blood clot event are at higher risk for another clot in the future. Up to 30% of those who have a DVT or PE will suffer another episode within 10 years, with the highest risk in the first 6 to 12 months.
For reasons that are not known, women are at lower risk for recurrent DVT than men. In one study of 826 patients (more than half were women), 9% of women compared with 31% of men had another episode of DVT within 5 years.
Recurrence is more likely if the first DVT was not caused by a one-time event such as trauma, surgery, or hormonal changes due to pregnancy, oral contraceptives, or hormone replacement therapy. Women who have ongoing factors that continue to put them at risk for DVT are more likely to have a recurrence, including those who have inherited blood clotting problems or cancer, or who are obese.
If you had a PE, the recurrence is more likely to be another PE (60% of the time). If you had a DVT without a PE, 80% of the time the recurrence is another DVT.
Chronic Vein Disease
Along with the risk of recurrent blood clots, women who have suffered DVT or PE are at increased risk for developing Chronic Venous Insufficiency (CVI). This happens when a blood clot damages the valves or lining of the veins in the legs, preventing them from sending enough blood back to the heart. Pulled down by gravity, blood pools in the legs causing symptoms like swelling, pain, skin problems and leg ulcers.
One in 5 DVT patients develops severe CVI within 10 years, and more than half have some signs of chronic vein disease.