Risk Factors for Pulmonary embolism

Risk Factors for Pulmonary embolism/Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream (embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathing in and coughing up blood. Symptoms of a blood clot in the leg may also be present, such as a red, warm, swollen, and painful leg.  Signs of a PE include low blood oxygen levels, rapid breathing, rapid heart rate, and sometimes a mild fever. Severe cases can lead to passing out, abnormally low blood pressure, and sudden death.

Causes of pulmonary embolism

Underlying causes

After a first PE, the search for secondary causes is usually brief. Only when a second PE occurs, and especially when this happens while still under anticoagulant therapy, a further search for underlying conditions is undertaken. This will include testing (“thrombophilia screen”) for Factor V Leiden mutation, antiphospholipid antibodies, protein C and S and antithrombin levels, and later prothrombin mutation, MTHFR mutation, Factor VIII concentration and rarer inherited coagulation abnormalities.[rx]

Probability testing

There are additional prediction rules for PE, such as the Geneva rule. More importantly, the use of any rule is associated with a reduction in recurrent thromboembolism.[rx]

The Wells score:

  • clinically suspected DVT — 3.0 points
  • alternative diagnosis is less likely than PE — 3.0 points
  • tachycardia (heart rate > 100) — 1.5 points
  • immobilization (≥ 3d)/surgery in previous four weeks — 1.5 points
  • history of DVT or PE — 1.5 points
  • hemoptysis — 1.0 points
  • malignancy (with treatment within six months) or palliative — 1.0 points

Traditional interpretation

  • Score >6.0 — High (probability 59% based on pooled data)
  • Score 2.0 to 6.0 — Moderate (probability 29% based on pooled data)
  • Score <2.0 — Low (probability 15% based on pooled data)

Alternative interpretation

  • Score > 4 — PE likely. Consider diagnostic imaging.
  • Score 4 or less — PE unlikely. Consider D-dimer to rule out PE.

Recommendations for a diagnostic algorithm were published by the PIOPED investigators; however, these recommendations do not reflect research using 64 slice MDCT.[36] These investigators recommended:

  • Low clinical probability. If negative D-dimer, PE is excluded. If positive D-dimer, obtain MDCT and based treatment on results.
  • Moderate clinical probability. If negative D-dimer, PE is excluded. However, the authors were not concerned that a negative MDCT with negative D-dimer in this setting has a 5% probability of being false. Presumably, the 5% error rate will fall as 64 slice MDCT is more commonly used. If positive D-dimer, obtain MDCT and based treatment on results.

Risk factors for pulmonary embolism

Surgery (in the last 3–6 months)
 Fracture (hip or leg) Hip or knee replacement
 Arthroscopic knee Laparoscopic surgery surgery (cholecystectomy)
 Cancer surgery Major trauma
 Spinal cord injury Major general surgery
 Central venous lines
Genetic diseases
 Factor V Leiden gene mutation Prothrombin G20210A mutation
 Protein C, S, anti-thrombin III deficiency Increased factor VIII
 Hyperhomocysteinemia Antiphospholipid antibody syndrome
 Anticardiolipin antibody syndrome Congenital dysfibrinogenemia
Additional diseases
 Previous VTE Congestive heart failure
 Congestive respiratory failure Myocardial infarction (in the last 1 month)
 Malignancy Nephrotic syndrome
 Varicose veins Paralytic stroke
 Primary myelofibrosis Polycythemia vera
 Inflammatory bowel disease
 Chemotherapy Obesity
 Hormone replacement therapy Bed rest > 3 days
 Pregnancy, postpartum Immobility due to sitting (more than 4 h)
 Increasing age Cigarette smoking


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Risk Factors for Pulmonary embolism

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