Pulmonary Embolism

Evaluation of PE (ACP 2015)

5 things to remember

  • Use validated clinical prediction rules to estimate the pretest probability (Simplified Well’s, modified Well’s or traditional Well’s, Geneva’s score)
    Modified WellSimplified Well
  • Low pretest probability + meet all PERC criteria = no D-dimer
  • Intermediate pretest probability or low risk but does not meet all PERC criteria = D-dimer is needed
  • Age adjusted D-dimer threshold (10 X age) for patients > 50 yo. If d-dimer below the age adjusted threshold, no further imaging studies.
  • For high pretest probability, obtain CTPA or VQ scan if CTPA is c/i or not available. Do not get a D-dimer.


** Alternative approach can be used if patint has symptoms of DVT – doing LE venous ultrasound. However, a single negative US should not be used to exclude subclinical DVT.

Common question: what is the fetal radiation risk of CTPA vs VQ scan?


Treatment of PE (BTS 2003)

5 things to remember:

  • Massive PE or imminent cardiac arrest = 50 mg alteplase
    Non massive PE, thrombolysis should not be used as first line.
  • Intermediate/high risk of PE = the first important thing is to give heparin (BEFORE imaging)
  • Oral anticoagulation only after you confirm the diagnosis.
  • Target INR is 2-3, discontinue heparin after target is reached.
  • Duration of treatment
    – 6 weeks for temporary reversible RF
    – 3 months for first idiopathic, then reassess at the end of 3 months.
    – At least 6 months for others

**SC LMWH is recommended over IV UFH unless rapid onset eg in massive PE is needed. Dose adjustment of LMWH is needed in renal failure.

Other things to consider

  • Consider testing hemophilia in <50 yo with recurrent PE or positive family history.
  • Cancer investigation only when it is suspected clinically.
  • IVC filter can be done as temporarizing measure until anticoagulation can be started.
  • Pregnancy: warfarin is teratogenic and should not be used until after delivery. Breast feeding is okay with warfarin.
    – Approaching delivery, UFH should be substituted
    because its anticoagulant effect can more easily be reversed if
    – There are different views about whether it should be
    discontinued or the dose reduced 4–6 hours before the
    expected time of delivery.
    – Continue anticoagulation for 6 weeks post-partum or 3 months,      whichever is longer.
  • Cancer: Same anticoagulation but remember that higher risk of recurrence and bleeding.
    – Duration is arbitary due to lack of good evidence.
    – Recurrent PE: higher target INR OR long term LMWH (both increase bleeding risk) or IVC filter (questionable value)

  1. Uae validated clinical prediction rule. If low risk, use PERC score to determine whether to get a D-dimer.
  2. If patient has symptoms of DVT, use LE ultrasound. Single negative US does not exclude subclinical PE.
  3. Thrombolysis only in massive PE.
  4. IV UFH or SC LMWH in intermediate/high probability of PE before the dx is confirmed. Oral anticoagulation after the dx is confirmed.
  5. Duration is 6 weeks with reversable RF, 3 months with first idiopathic and 6 months with the others.
  6. In pregnancy, warfarin is contraindicated BUT is okay after delivery and does not preclude breast feeding. Anticoagulation for 6 wks PP or 3 months, whichever is longer.
  7. Cancer patient has higher risk of bleeding and recurrence. Recurrent PE in malignancy is very difficult to be managed with poor evidence supporting one over another. (increase target INR vs long term LMWH vs IVC filter).


Evaluation of Patients With Suspected Acute Pulmonary Embolism:
Best Practice Advice From the Clinical Guidelines Committee of the
American College of Physicians

British Thoracic Society guidelines for the management of
suspected acute pulmonary embolism. Thorax 2003;58:470–484


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