Venous Thromboembolism 

Deep vein thrombosis (DVT) occurs when a blood clot forms in a deep vein, usually in the legs. If a fragment of the blood clot breaks loose and migrates to the lungs, it may cause a pulmonary embolism (PE), a potentially life-threatening complication of DVT. DVT and PE are collectively named venous thromboembolism (VTE) 

  • One person is diagnosed with a blood clot every minute1
  • One person dies from a blood clot every six minutes1
  • After an initial episode of DVT/PE, the risk of recurrence is about 10% within 1 year and 40% within 10 years4,2

Definition

Deep vein thrombosis (DVT) occurs when a blood clot forms in the deep veins of the body, usually the leg, although the arm, abdomen or the area around the brain can also be affected. The clot can form due to damage to a vein, or to a thickening or slowing of the blood circulating in the body. A potentially fatal complication of DVT, a pulmonary embolism (PE), occurs if the blood clot breaks off, travels through the blood stream and reaches the lung.

Ten to 30% of people diagnosed with DVT/PE will die within one month3. Many people who experience DVT will have long-term complications such as pain, swelling, skin discoloration, and scaling or ulcers in the affected limb and up to 40% will have a recurrence within 10 years2,3.

Since the signs and symptoms are often unspecific or similar to other conditions, DVT may be undiagnosed or misdiagnosed3,4. DVT affects men and women, of all ages and all races. Many of the known risk factors (see chart) are rising, making DVT/PE a growing public health problem3.

Risk factors for DVT/PE1,2,4

  • Injury to a vein (such as from a fracture or surgery)
  • Immobility  (such as during long travel or hospitalization)
  • Surgery
  • An increase in estrogen (from birth control, hormone replacement or pregnancy)
  • Certain medical conditions and/or treatments (such as cancer/chemotherapy, heart failure, inflammatory disorders or kidney disorders)
  • Genetic predisposition
  • Old age
  • Obesity
  • Smoking
     

Diagnosis

A patient is suspected of having DVT and/or PE based on medical history, risk factors and presenting symptoms (see chart). If a blood clot is suspected, medical tests will be done2. These tests include:

  • D-dimer blood tests: These measure D-dimer, a substance found in blood that increases in the case of large obstructing clots1
    • D-dimer tests can safely exclude DVT/PE in  up to 50% of suspected outpatients attending the Emergency Department5,6
    • Used in combination with clinical assessment, D-dimer tests help avoid unnecessary and costly imaging5,7
  • Imaging tests to diagnose DVT include:  Doppler ultrasound, venography or MRI venography1,4
  • Imaging tests to diagnose PE include: Computed tomography (CT scan), ventilation/perfusion lung scan or pulmonary angiography1,4

Signs and symptoms of DVT & PE1,4

  • Deep Vein Thrombosis (DVT):
  • Pain/tenderness
  • Swelling
  • Discoloration of skin (bluish, purplish or reddish)
  • Skin warm to the touch
  • Pulmonary Embolism (PE):
  • Shortness of breath
  • Chest pain (possibly worse with deep breathing)
  • Unexplained cough/coughing up blood
  • Unexplained rapid heart rate​

     

Prevention / Treatment

Prevention

Although DVT can affect anyone, there are a number of things that can help prevent it.1,4

  • Stay active
  • Maintain a healthy weight
  • If sitting for long periods (such as when travelling long distances) take breaks,  stretch legs, wear loose clothes and drink plenty of water
  • For longer hospitalizations: talk to a healthcare provider about prevention and any risk factors to take steps to prevent
  • Anticoagulants may be prescribed for specific risk factors such as a previous episode, or post-surgery or hospitalization
  • Compression stockings may help for specific risk factors such as previous episode, varicose veins or surgery
     

Treatment

Anticoagulants – blood thinners – are the first line of treatment for DVT and PE. They help prevent blood from clotting and existing clots from growing, and can help prevent DVT from leading to PE.1,4 Compression stockings may be recommended to relieve pain and swelling. If PE is suspected, immediate medical attention is important. For severe PE, thrombolytic medication may be administered to dissolve the clot, followed by anticoagulants to prevent more clots from forming1,5.
 

Guidelines

 

REFERENCES

1.     Clotconnect.org. “Patient Information Guide: Deep Vein Thrombosis and Pulmonary Embolism” 

2.     Prandoni P, et al. The risk of recurrent venous thromboembolism after discontinuing anticoagulation in patients with acute proximal deep vein thrombosis or pulmonary embolism. A prospective cohort study in 1,626 patients. Haematologica. 2007;92:199-205.

3.     Beckman, MG, et. al. Venous thromboembolism: a public health concern. Am J Prev Med. 2010;38:S495-501

4.     CDC: DVT and PE Fact Sheet

5.     Righini M et al. J Thromb Haemost. 2007 ;5 :1869-77

6.     Ten Cate-Hoek AJ et al. J Throm Haemost. 2005;3:2465-70

7.     Wayne, PA, Clinical and Laboratory Standards Institute (CLSI). Quantitative D-dimer for the exclusion of venous thromboembolic disease; approved guideline. CLSI document H59-A. USA, 2011

 

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