For Patients

Symptoms, Risk Factors and Prevention


What are blood clots?

When a clot forms in the deep veins of the body, it is called deep vein thrombosis, often referred to as DVT for short.  DVT occurs most commonly in the leg; although it can occur anywhere in the body, such as the veins in the arm, abdomen, or around the brain.

Deep Vein Thrombosis (DVT): 

Symptoms range from mild to severe; may involve the foot, ankle, calf, whole leg or arm. The classic symptoms are:

  • Pain
  • Swelling
  • Discoloration (bluish or reddish)
  • Warmth

A potentially life-threatening complication of deep vein thrombosis (DVT) is pulmonary embolism, often referred to as PE for short. A PE occurs when a blood clot breaks off, travels through the blood stream and lodges in the lung.

Pulmonary Embolism (PE):

A blood clot in the lungs.  The classic symptoms are:

  • Shortness of breath
  • Chest pain (may be worse with deep breath)
  • Unexplained cough (may cough up blood)
  • Unexplained rapid heart rate

If you suspect a blood clot, get medical attention right away.  Don't delay.  

Symptoms may be mild to severe or there may be none noticeable at all.  There can be a wide range of presentations and one does not need to have all symptoms to have a blood clot.

Symptoms of blood clots may also be subtle and easily confused with other medical conditions.

  • Deep vein thrombosis (DVT) may be confused with sprained ankle, ‘Charley horse’, or pulled muscle. 
  • Pulmonary embolism (PE) may be attributed as ‘a touch of pneumonia’, new onset of asthma, respiratory infection, inflammation of the joints of the breast bone or ribs.

Because symptoms of DVT and PE can mimic these conditions, a wrong or delayed diagnosis can occur in patients who eventually get diagnosed with DVT or PE.  

What causes blood clots?

Blood clots may form when either the flow of blood in a vein slows, damage to a vein occurs, or the blood is more clotable. Many factors can increase a person’s risk for developing a blood clot in a vein. Common risk factors for developing a blood clot include:


  • Hospitalization
  • Being paralyzed
  • Prolonged sitting

Surgery and Trauma:

  • Major surgery (especially of the pelvis, abdomen, hip, knee)
  • Bone fracture or cast
  • Catheter in a big vein (PICC line, central venous catheter, or port)

Increased estrogens:

  • Birth control pills, patches, rings
  • Pregnancy, including up to 6 weeks after giving birth
  • Estrogen and progestin hormone therapy

Medical conditions:

  • Cancer and chemotherapy
  • Heart failure
  • Inflammatory disorders (lupus, rheumatoid arthritis, inflammatory bowel disease)
  • The kidney disorder called nephrotic syndrome

Other risk factors:

  • Previous blood clot
  • Family history of clots
  • Clotting disorder (inherited or acquired)
  • Obesity
  • Older age
  • Cigarette smoking
  • Varicose veins

What can you do to prevent blood clots?

  • Stay active.  Immobility increases the risk of developing clots. If you've been sitting for a long period of time (such as long-distance travel)   stop and take a break to stretch your legs.
  • Maintain an ideal body weight.  
  • Know your risk factors for developing a clot (above) and discuss these with your doctor.
  • Know your family medical history.  Make sure your doctor knows about any history of blood clots.
  • If you are hospitalized or planning for surgery, ask your doctor:   ‘What will be done to prevent blood clots?’ You may be given a blood-thinning medication (anticoagulant) or special stockings designed to prevent blood clots.  These blood clot prevention measures are called 'DVT prophylaxis'.