Deep Venous Thrombosis (DVT)
What is a DVT?
DVT or deep venous thrombosis is a blood clot that forms in the deep system
of veins in your legs. It usually starts as a small clot behind one of the
valves in the vein, and progresses to cause a blockage throughout the vein. Risk
factors for developing a DVT are prolonged sitting or lying flat, damage to
lining of the vein (trauma) or abnormal blood clotting (hypercoaguable state).
People who are risk for DVT include people who are obese, pregnant women, women
on estrogen pills, people with cancer, people with varicose veins, people
confined to bed or a chair, and people who have had an injury to their legs.
Patients will complain of acute pain and swelling of their leg, which usually
only on one side. In severe cases, the leg can appear pale or blue.
Why is the treatment of DVT important?
A DVT can cause a patient pain and loss of function in their leg.
Importantly, the blood clot that forms in the leg can break off and become
lodged in the blood vessels in the lung (pulmonary embolism). This can be life
threatening. Also, if the swelling in the leg becomes severe, the blood supply
to the leg can become comprised and the leg can turn white (phlegmasia alba
dolens) or blue (phlegmasia cerulea dolens). If this occurs, the patient is at
risk of losing their limb.
How can DVT be diagnosed?
A person that has the symptoms of DVT should see a doctor. Most doctors will
look for blood clots deep in the legs with an ultrasound test (venous duplex).
Other tests that can be performed include venous plethysmography (performed with
blood pressure cuffs) and fibrinogen scanning (nuclear medicine test looking for
the formation of new clot). A venogram (x-ray study with the injection of
contrast into the vein) is rarely needed for the diagnosis of a DVT.
How is a DVT treated?
DVT is treated with bedrest and blood thinners. This usually requires a
patient to be admitted to the hospital for 5-7 days for the medicines to reach
an adequate level in the blood. An IV blood thinner (Heparin) is given
immediately to prevent the clot from extending, and later a pill is given for
long-term blood thinning (Coumadin). Pregnant women cannot take Coumadin (may
cause birth defects) and must take injectable Heparin until they deliver. During
the first 5-7 days, the patient must be confined to bed, to prevent the clot
from breaking up and lodging in the lung.
New injectable blood thinners (Lovenox) have recently been used for the
treatment of DVT. These can be injected at home, and may reduce the need for
hospitalization. This newer therapy can be used when only mild to moderate leg
swelling is present.
What is a Vena Caval filter (Greenfield) and when is it used?
A vena caval filter is a metal basket that is inserted through the leg vein
and rests in the large vein (vena cava) in your abdomen. This basket prevents
blood clots from traveling up from the legs and lodging in the lungs. It is
given to patients that cannot take blood thinners or those that developed
pulmonary emboli despite already being on blood thinners.