TRAINING and EDUCATION
Patient Education
UNDERSTANDING
BLOOD CLOTS
Thrombosis in leg vein
As many as 900,000 people in the United States develop blood clots annually, and clots are
responsible for approximately 100,000 deaths each year. Research has shown that fewer than one in
four people has any recognizable signs and symptoms of a blood clot, so understanding the risk for
blood clots is an important factor in identifying symptoms and seeking treatment in a timely manner.
Read below for more information about the diagnosis, treatment, and prognosis of blood clots.
This “Patient Education” tear sheet was produced in collaboration with the National Blood Clot
Alliance (stoptheclot.org).
What Is a Blood Clot?
A blood clot (thrombosis) is a gelatinous or semi-solid mass of co-
agulated (congealed) blood that develops in the veins of the body.
Deep vein thrombosis (DVT) occurs when a blood clot forms
in one of the deep veins of the body. These usually occur in the
legs, but can sometimes occur in the arms.
Clots can break off from a DVT (most likely in the legs, groin,
or pelvic area) and travel to the lung, causing a pulmonary em-
bolism (PE), which can be fatal.
How Are Blood Clots Diagnosed?
People who might have a dangerous blood clot may undergo
a number of tests, including a blood test called a D-dimer test,
as well as other laboratory tests and imaging scans to diagnose
blood-clotting problems.
Deep Vein Thrombosis
Most often, DVT is diagnosed by ultrasound, which is a
non-invasive test. If the results are not definitive, then
venography (an invasive test using contrast dye) or magnetic
resonance imaging may be used.
Pulmonary Embolism
For PE, a lung ventilation/perfusion scan is performed, but
if it does not identify a clot – and one is still suspected – a
pulmonary angiogram is performed. During a pulmonary
angiogram, a catheter is threaded through a vein in the groin
and passed through the heart into the pulmonary artery.
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Contrast dye is then injected and X-rays are taken to monitor
blood flow in the lung. The angiogram will give a definite
diagnosis as to the presence of a clot.
What Are the Symptoms and Risks of a Blood Clot?
The signs and symptoms of a DVT (clot in the legs or arms) include:
• swelling, usually in one leg or arm
• pain or tenderness in the leg or arm (often described as a
cramp or charley horse)
• reddish or bluish skin discoloration
• leg or arm that is warm to the touch
If you experience any of these symptoms, you should see a
doctor as soon as possible.
The signs and symptoms of PE include:
• sudden shortness of breath
• sharp and/or stabbing chest pain that may get worse with a
deep breath
• rapid heart rate
• unexplained cough, sometimes with bloody mucus
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