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Pulmonary Embolism DiagnosisAka: Pulmonary Embolus Diagnosis, PE Diagnosis, PE Probability

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  1. See Also
    1. Pulmonary Embolism
    2. Pulmonary Embolism Pretest Probability
  2. Step 1: Consider Differential Diagnosis
    1. See Chest Pain Causes
    2. See Dyspnea Causes
    3. See Leg Pain Causes
  3. Step 2: Define Typical, Atypical or Severe PE Symptoms
    1. Typical PE Criteria
      1. Two or more Column A factors
        1. Dyspnea (new or progressive)
        2. Pleuritic Chest Pain
        3. Hemoptysis
        4. Pleural rub
        5. Oxygen Saturation on room air <92%
      2. One or more Column B factors
        1. Heart Rate over 90 per minute
        2. Low grade fever (<101 Fahrenheit)
        3. Leg symptoms suggestive of Deep Vein Thrombosis
        4. Chest XRay suggestive of Pulmonary Embolism
    2. Severe PE Criteria
      1. Primary Criteria
        1. Typical PE Criteria met (see above) or
        2. Atypical unexplained hypotension, Syncope, Hypoxia
      2. Additional signs suggestive of severe PE
        1. Syncope
        2. Systolic Blood Pressure <90 mmHg
        3. Heart Rate above 100 (tachycardia)
        4. Supplemental Oxygen required >40% FiO2
        5. Signs of new right ventricular strain pattern
          1. Electrocardiogram (EKG) with S1 Q3 T3 pattern
          2. EKG with new Right Bundle Branch Block
    3. Atypical PE Criteria
      1. Nonspecific cardiopulmonary symptoms
      2. Typical criteria not met (see above)
  4. Step 3: Assess Significant Thromboembolic Risk Factors
    1. See Pulmonary Embolism Risk Factors
    2. See Wells Clinical Prediction Rule for PE
      1. Accounts for many of these major risk factors
    3. Deep Vein Thrombosis or Pulmonary Embolism history
      1. Family History of Thromboembolism is >2 relatives
      2. Past Medical History of prior event
    4. Cancer
      1. Treatment in last 6 months
      2. Palliative care
    5. Paralysis
    6. Bedrest (3 days within the last 4 weeks)
    7. Lower extremity plaster immobilization (last 12 weeks)
    8. Recent Surgery in past 12 weeks
    9. Obstetrical delivery in last 12 weeks
  5. Step 4: Determine Pulmonary Embolism Probability
    1. See Pulmonary Embolism Pretest Probability
    2. Low Probability for Pulmonary Embolism
      1. Alternative diagnosis more likely than PE
        1. Atypical PE signs with or without risk factors
        2. Typical PE signs without risk factors
      2. PE more likely than alternative diagnosis
        1. Atypical PE signs without risk factors
    3. Moderate Probability for Pulmonary Embolism
      1. Alternative diagnosis more likely than PE
        1. Typical PE signs with risk factors
        2. Severe PE signs with or without risk factors
      2. PE more likely than alternative diagnosis
        1. Atypical PE signs with risk factors
        2. Typical PE signs without risk factors
    4. High Probability for Pulmonary Embolism
      1. PE more likely than alternative diagnosis
        1. Typical PE signs with risk factors
        2. Severe PE signs with or without risk factors
  6. Step 5: Determine Diagnostic Approach
    1. Obtain Imaging Study
      1. CT Pulmonary Angiography (preferred)
      2. Ventilation-Perfusion Scan (VQ Scan)
    2. No further diagnostic testing Needed
      1. High Probability PE with high probability imaging
        1. High probability VQ Scan or positive CT angiography
        2. See Pulmonary Embolism Management
      2. Low Probability PE with Normal VQ Scan
        1. No treatment needed
        2. Evaluate alternative diagnoses
    3. Additional testing needed
      1. Negative CT angiography or nondiagnostic VQ Scan
        1. Compression ultrasound of lower extremities
        2. Positive Compression Ultrasound
          1. Treat as Pulmonary Embolism
        3. Negative Compression Ultrasound
          1. Low probability PE: Consider other diagnosis
          2. Moderate probability PE
            1. Obtain D-Dimer or repeat compression ultrasound
            2. Negative test: Consider other diagnosis
            3. Positive test: Treat as Pulmonary Embolism
          3. High probability PE: Perform Angiography
            1. Negative Angiography: Consider other diagnosis
            2. Positive Angiography: Treat as PE
      2. High probability VQ Scan with Low probability PE
        1. Angiography
        2. Negative angiography: Evaluate other diagnosis
        3. Positive angiography: Treat as Pulmonary Embolism
    4. Evaluate based on clinical probability
      1. Pulmonary Embolism Low Probability Evaluation
      2. Pulmonary Embolism Moderate Probability Evaluation
      3. Pulmonary Embolism High Probability Evaluation
  7. References
    1. Ramzi (2004) Am Fam Physician 69:2829
    2. Ryu (2001) Mayo Clin Proc 76:63
    3. Wells (1998) Ann Intern Med 129(12):997

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