Pulmonary embolism

Last updated: March 23, 2022

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Pulmonary embolism (PE) is the obstruction of one or more pulmonary arteries by solid, liquid, or gaseous masses. In most cases, the embolism is caused by blood thrombi, which arise from the deep vein system in the legs or pelvis (deep vein thrombosis) and embolize to the lungs via the inferior vena cava. Risk factors include immobility, inherited hypercoagulability disorders, pregnancy, puerperium, and recent surgery. The clinical presentation is variable and, depending on the extent of vessel obstruction, can range from asymptomatic to obstructive shock. Symptoms are often nonspecific, including chest pain, coughing, dyspnea, and tachycardia. The diagnosis of PE is based primarily on the clinical findings and is confirmed by the detection of an embolism in CT pulmonary angiography (CTPA). Arterial blood gas analysis typically shows evidence of respiratory alkalosis with low partial oxygen pressure, low partial carbon dioxide pressure, and elevated pH. Another commonly performed test is the measurement of D-dimer levels, which can rule out PE if negative. Anticoagulation with heparin is initiated to prevent further thromboembolisms as well as to promote the gradual dissolution of the embolism and the underlying thrombosis. In massive PE with obstructive shock, the thrombus is resolved with thrombolytic agents or embolectomy.

Epidemiological data refers to the US, unless otherwise specified.

PE is FATAL: PE caused by Fat, Air, Thrombus, Amniotic fluid, and Less common, i.e., bacterial, tumor, and cement.

Consider PE as a differential diagnosis in recurring or progressive dyspnea of uncertain etiology.

There are several externally validated decision tools that can be used to assess the pretest probability of PE. These include the original Wells score and modified Wells score, revised Geneva score, and pulmonary embolism rule-out criteria (PERC). None of these scoring systems have been found to have greater levels of accuracy than the others. [7][8]

Wells criteria for pulmonary embolism [9]

The Wells score is a diagnostic algorithm for assessing the probability of PE and has been validated in inpatient and outpatient settings. Note that a different version is used for determining the probability of DVT. (See “Wells criteria for DVT.”)

Wells criteria for PE [10][11]
Criteria Points
Clinical symptoms of DVT 3
PE more likely than other diagnoses 3
Previous PE/DVT 1.5
Tachycardia (Heart rate > 100/min) 1.5
Surgery or immobilization in the past 4 weeks 1.5


Malignancy 1
Original Wells score (clinical probability) [10]

Modified Wells score (clinical probability) [11]

  • Total score ≤ 4: PE unlikely (8%)
  • Total score > 4: PE likely (34%)

Revised Geneva score [12]

The revised Geneva score utilizes objective clinical variables. It has been externally validated and was initially studied in emergency department outpatients.

Revised Geneva score [10]
Criteria Points
Age > 65 years 1
Prior history of DVT or PE 3
Recent surgery or fracture of the lower limbs 2
Personal history of cancer 2
Unilateral lower limb pain 3
Hemoptysis 2
Heart rate 75–94/min 3
Heart rate ≥ 95/min 5
Pain on palpation of lower limb and unilateral edema 4

Clinical pretest probability

Pulmonary embolism rule-out criteria (PERC) [8][13][14]

PERC is only used for patients who have a low pretest probability of PE based on either their Wells score for pulmonary embolism or revised Geneva score.

Pulmonary embolism rule-out criteria (PERC)
Criteria Points
Age > 50 years 1
Heart rate > 100/min 1
Oxygen saturation < 95% 1
Hemoptysis 1
Estrogen use 1
Prior history of DVT or PE 1
Recent surgery or trauma in the past 4 weeks 1
Unilateral lower limb edema 1

Clinical pretest probability

  • Total score 0: pretest probability < 1%; no further testing needed
  • Total score ≥ 1: PE is not ruled out; further testing needed

PERC should only be used in patients with a low pretest probability of PE.

Diagnostic approach [5][8]

  1. Assess for hemodynamic stability.
    • Stable patients: systolic BP > 90 mm Hg
    • Unstable patients: systolic BP < 90 mm Hg for > 15 minutes, evidence of shock, or BP drop > 40 mm Hg for > 15 minutes
  2. Assess the pretest probability of PE.
  3. Obtain other laboratory studies or imaging as needed.

Laboratory studies [8]

D-dimer levels [8]

  • Indication: pretest probability of PE is either low and does not meet PERC OR is intermediate
  • Findings
    • Normal levels: < 500 ng/mL
    • If ≥ 500 ng/mL: Further testing is required (see below).
    • If the patient is > 50 years of age, adjust for age: age x 10 ng/mL = cut off value in ng/mL
  • Interpretation

Normal D-dimer values can usually rule out PE or DVT in patients with unremarkable history and physical examination! A positive D-dimer is nonspecific, since it may be elevated in any situation where there is increased fibrinolysis.

Additional testing


CT pulmonary angiography (CTPA)

Ventilation/perfusion scintigraphy (V/Q scan) [20]

Echocardiography [22]

Lower extremity venous ultrasound [20]

Chest x-ray [20]

Pulmonary angiography [20]

  • Definition: an invasive radiological procedure performed with contrast dye to visualize the pulmonary vasculature
  • Procedure: Right heart catheterization insertion of a catheter into a pulmonary artery→ angiography following administration of contrast agent
  • Indications
    • Planning of concomitant endovascular treatment [20]
    • Suspicion for PE is high despite negative findings. [19]
  • Findings: intraluminal filling defects in pulmonary arteries

Magnetic resonance pulmonary angiography [25]

  • Indications: when standard imaging (CTPA or V/Q scan) cannot be performed
  • Findings: similar to CTPA [20]

Additional diagnostics

Electrocardiography (ECG) [26]

Identifying the underlying cause


  1. Stabilize the patient and provide supportive care.
    • Pulseless patient with suspected PE: Start ACLS and consider administration of thrombolytics (e.g., tPA ). [33][34].
  2. Assess bleeding risk (see risk factors for bleeding in patients with VTE).
  3. Consider empiric parenteral anticoagulation while awaiting a definitive diagnosis.
  4. Risk stratify the patient based on prognostic models (see risk stratification of pulmonary embolism).
  5. Consult pulmonary embolism response team (PERT), if available. [35]
  6. Initiate therapy based on risk stratification and bleeding risk.

Supportive care

Hypervolemia can be harmful if right ventricle strain is present.

Assessment of bleeding risk

There are currently no scoring systems with sufficient prediction outcomes for the bleeding risk from anticoagulant therapy in patients with PE. The HAS-BLED score is sometimes used but it was designed and validated for anticoagulant therapy in patients with atrial fibrillation. See risk factors for bleeding in patients with VTE. [37]

Empiric parenteral anticoagulation for pulmonary embolism

  • Indications: consider starting empiric anticoagulation in patients awaiting a definitive diagnosis, depending on the risk of bleeding, the pretest probability of PE, and the expected timing of the diagnostic study ; [34][36]
    • Low probability of PE and diagnostic study is expected to be delayed > 24 hours [34]
    • Intermediate probability of PE and diagnostic study is expected to be delayed > 4 hours [34]
    • High probability of PE
  • Absolute contraindication: high bleeding risk
  • Choice of medication [34][36]

An absolute contraindication for empiric anticoagulation is a high risk of bleeding (e.g., recent surgery, hemorrhagic stroke, active bleeding).

Risk stratification of pulmonary embolism

Risk categories based on the risk of adverse outcomes [39][40]

Pulmonary Embolism Severity Index (PESI) and simplified PESI (sPESI) [41][42]

The Pulmonary Embolism Severity Index stratifies the risk of mortality or adverse outcomes and is used to assist in decisions on inpatient vs. outpatient management.

Criteria Points
PESI [41] sPESI [42]
Age 1 per year 1 if > 80 years
History of cancer 30 1
Systolic blood pressure < 100 mm Hg 30 1
Heart rate ≥ 110/min 20 1
O2 saturation on room air < 90% 20 1
Heart failure 10 1
Chronic lung disease 10
Altered mental status 60 Not considered
Temperature < 96.8°F (< 37°C) 20
Respiratory rate ≥ 30/min 20

Male: 10

Female: 0

PESI interpretation (30-day mortality rate, inpatient mortality) [41]

  • < 66 points: class I, very low risk (0–1.6%, ≤ 1.1%)
  • 66–85 points: class II, low risk (1.7–3.5%, ≤ 1.9%)
  • 86–105 points: class III, intermediate risk (3.2–7.1%, ≤ 4.7%)
  • 106–125 points: class IV, high risk (4.0–11.4%, ≤ 7.0%)
  • > 125 points: class V, very high risk (10.0–23.9%, ≤ 17.2%)

sPESI interpretation (30-day mortality) [42]

  • 0 points: low risk (1%)
  • ≥ 1 point: high risk (10.9%)

Treatment of massive pulmonary embolism

Initiate directed therapy based on bleeding risk and the presence of any contraindications to thrombolytic therapy in massive pulmonary embolism.

Thrombolytic therapy in pulmonary embolism

Systemic thrombolysis [38]

Catheter-directed thrombolysis [38]

Contraindications to thrombolysis

Contraindications to thrombolytic therapy in massive pulmonary embolism [38]
Absolute contraindications
Relative contraindications

Embolectomy in pulmonary embolism [34]

  • Indication: : treatment of last resort when thrombolysis is contraindicated or unsuccessful
  • Procedure: surgical embolectomy (removal of an embolus by opening up an artery with an incision) or catheter-based thrombus removal

Treatment of nonmassive pulmonary embolism and submassive pulmonary embolism

Initiate directed therapy based on the bleeding risk on anticoagulation for VTE.

Anticoagulation for pulmonary embolism [34][38][40][45]

Specific populations [38]

Initial management

Nonmassive and submassive pulmonary embolism

Massive pulmonary embolism

Pulseless patient with suspected PE

  • Start ACLS.
  • Consider administration of reduced dose of tPA.

We list the most important complications. The selection is not exhaustive.

  • Purpose: distinguishing cause of embolism (See “Etiology” above.)
  • Histological findings [46]
    • Lines of Zahn: alternating layers of platelets mixed with fibrin (light pink layers) and red blood cells (dark red layers)
    • Only appear premortally (help distinguish a premortal thrombus from a postmortem one)

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  1. Ageno W, Squizzato A, Wells PS, Büller HR, Johnson G. The diagnosis of symptomatic recurrent pulmonary embolism and deep vein thrombosis: guidance from the SSC of the ISTH. Journal of Thrombosis and Haemostasis. 2013; 11 (8): p.1597-1602. doi: 10.1111/jth.12301 . | Open in Read by QxMD
  2. Beckman MG, Hooper WC, Critchley SE, Ortel TL. Venous Thromboembolism. Am J Prev Med. 2010; 38 (4): p.S495-S501. doi: 10.1016/j.amepre.2009.12.017 . | Open in Read by QxMD
  3. Calkovska A, Mokra D, Calkovsky V. Lung surfactant alterations in pulmonary thromboembolism. Eur J Med Res. 2009; 14 (Suppl 4): p.38. doi: 10.1186/2047-783x-14-s4-38 . | Open in Read by QxMD
  4. Lyhne MD, Kline JA, Nielsen-Kudsk JE, Andersen A. Pulmonary vasodilation in acute pulmonary embolism – a systematic review. Pulmonary Circulation. 2020; 10 (1): p.204589401989977. doi: 10.1177/2045894019899775 . | Open in Read by QxMD
  5. Agnelli G, Becattini C. Acute Pulmonary Embolism. N Engl J Med. 2010; 363 (3): p.266-274. doi: 10.1056/nejmra0907731 . | Open in Read by QxMD
  6. Hagio K, Sugano N, Takashina M, Nishii T, Yoshikawa H, Ochi T. Embolic events during total hip arthroplasty: An echocardiographic study. J Arthroplasty. 2003; 18 (2): p.186-192. doi: 10.1054/arth.2003.50027 . | Open in Read by QxMD
  7. Raja AS, Greenberg JO, Qaseem A, et al. Evaluation of Patients With Suspected Acute Pulmonary Embolism: Best Practice Advice From the Clinical Guidelines Committee of the American College of Physicians. Ann Intern Med. 2015; 163 (9): p.701-11. doi: 10.7326/m14-1772 . | Open in Read by QxMD
  8. Rodger MA, Carrier M, Jones GN, et al. Diagnostic Value of Arterial Blood Gas Measurement in Suspected Pulmonary Embolism. Am J Respir Crit Care Med. 2000; 162 (6): p.2105-2108. doi: 10.1164/ajrccm.162.6.2004204 . | Open in Read by QxMD
  9. Stein PD, Goldhaber SZ, Henry JW, Miller AC. Arterial Blood Gas Analysis in the Assessment of Suspected Acute Pulmonary Embolism. Chest. 1996; 109 (1): p.78-81. doi: 10.1378/chest.109.1.78 . | Open in Read by QxMD
  10. Müller-Bardorff M, Weidtmann B, Giannitsis E, Kurowski V, Katus HA. Release kinetics of cardiac troponin T in survivors of confirmed severe pulmonary embolism.. Clin Chem. 2002; 48 (4): p.673-5.
  11. Klok FA, Mos ICM, Huisman MV. Brain-Type Natriuretic Peptide Levels in the Prediction of Adverse Outcome in Patients with Pulmonary Embolism. Am J Respir Crit Care Med. 2008; 178 (4): p.425-430. doi: 10.1164/rccm.200803-459oc . | Open in Read by QxMD
  12. Wilbur J, Shian B. Diagnosis of deep venous thrombosis and pulmonary embolism.. Am Fam Physician. 2012; 86 (10): p.913-9.
  13. Moore AJE, Wachsmann J, Chamarthy MR, Panjikaran L, Tanabe Y, Rajiah P. Imaging of acute pulmonary embolism: an update. Cardiovasc Diagn Ther. 2018; 8 (3): p.225-243. doi: 10.21037/cdt.2017.12.01 . | Open in Read by QxMD
  14. Sostman HD, Stein PD, Gottschalk A, Matta F, Hull R, Goodman L. Acute Pulmonary Embolism: Sensitivity and Specificity of Ventilation-Perfusion Scintigraphy in PIOPED II Study. Radiology. 2008; 246 (3): p.941-946. doi: 10.1148/radiol.2463070270 . | Open in Read by QxMD
  15. Fields JM, Davis J, Girson L, et al. Transthoracic Echocardiography for Diagnosing Pulmonary Embolism: A Systematic Review and Meta-Analysis.. J Am Soc Echocardiogr. 2017; 30 (7): p.714-723.e4. doi: 10.1016/j.echo.2017.03.004 . | Open in Read by QxMD
  16. Meyerovitz MF, Mannting F, Polak JF, Goldhaber SZ. Frequency of Pulmonary Embolism in Patients with Low-Probability Lung Scan and Negative Lower Extremity Venous Ultrasound. Chest. 1999; 115 (4): p.980-982. doi: 10.1378/chest.115.4.980 . | Open in Read by QxMD
  17. Van Rossum AB, van Houwelingen HC, Kieft GJ, Pattynama PM. Prevalence of deep vein thrombosis in suspected and proven pulmonary embolism: a meta-analysis.. Br J Radiol. 1998; 71 (852): p.1260-1265. doi: 10.1259/bjr.71.852.10318998 . | Open in Read by QxMD
  18. Stein PD. Gadolinium-Enhanced Magnetic Resonance Angiography for Pulmonary Embolism. Ann Intern Med. 2010; 152 (7): p.434-43. doi: 10.7326/0003-4819-152-7-201004060-00008 . | Open in Read by QxMD
  19. Shopp JD, Stewart LK, Emmett TW, Kline JA. Findings From 12-lead Electrocardiography That Predict Circulatory Shock From Pulmonary Embolism: Systematic Review and Meta-analysis. Acad Emerg Med. 2015; 22 (10): p.1127-1137. doi: 10.1111/acem.12769 . | Open in Read by QxMD
  20. Co I, Eilbert W, Chiganos T. New Electrocardiographic Changes in Patients Diagnosed with Pulmonary Embolism. J Emerg Med. 2017; 52 (3): p.280-285. doi: 10.1016/j.jemermed.2016.09.009 . | Open in Read by QxMD
  21. Geibel A, Zehender M, Kasper W, et al. Prognostic value of the ECG on admission in patients with acute major pulmonary embolism. European Respiratory Journal. 2005; 25 (5): p.843-848. doi: 10.1183/09031936.05.00119704 . | Open in Read by QxMD
  22. Alreshq R, Hsu G, Torosoff M. Acute Pulmonary Embolism Presenting with Symptomatic Bradycardia: A Case Report and Review of the Literature. Am J Case Rep. 2019; 20 : p.748-752. doi: 10.12659/ajcr.915609 . | Open in Read by QxMD
  23. Daniel KR, Courtney DM, Kline JA. Assessment of Cardiac Stress From Massive Pulmonary Embolism With 12-Lead ECG. Chest. 2001; 120 (2): p.474-481. doi: 10.1378/chest.120.2.474 . | Open in Read by QxMD
  24. Mohsen A, El-Kersh K. Variable ECG findings associated with pulmonary embolism. Case Reports. 2013; 2013 (feb28 1): p.bcr2013008697-bcr2013008697. doi: 10.1136/bcr-2013-008697 . | Open in Read by QxMD
  25. Connors JM. Thrombophilia Testing and Venous Thrombosis. N Engl J Med. 2017; 377 (12): p.1177-1187. doi: 10.1056/nejmra1700365 . | Open in Read by QxMD
  26. Sharifi M, Berger J, Beeston P, Bay C, Vajo Z, Javadpoor S. Pulseless electrical activity in pulmonary embolism treated with thrombolysis (from the “PEAPETT” study). Am J Emerg Med. 2016; 34 (10): p.1963-1967. doi: 10.1016/j.ajem.2016.06.094 . | Open in Read by QxMD
  27. Kearon C, Akl EA, Comerota AJ, et al. Antithrombotic therapy for VTE disease: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines.. Chest. 2012; 141 (2 Suppl): p.e419S-e496S. doi: 10.1378/chest.11-2301 . | Open in Read by QxMD
  28. Chaudhury P, Gadre S, Schneider E, et al. Impact of Multidisciplinary Pulmonary Embolism Response Team Availability on Management and Outcomes.. Am J Cardiol. 2019; 124 (9): p.1465-1469. doi: 10.1016/j.amjcard.2019.07.043 . | Open in Read by QxMD
  29. Konstantinides SV, Meyer G, Becattini C, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Respir J. 2019; 54 (3): p.1901647. doi: 10.1183/13993003.01647-2019 . | Open in Read by QxMD
  30. Klok FA, Niemann C, Dellas C, et al. Performance of five different bleeding-prediction scores in patients with acute pulmonary embolism.. J Thromb Thrombolysis. 2016; 41 (2): p.312-20. doi: 10.1007/s11239-015-1239-x . | Open in Read by QxMD
  31. Ruíz-Giménez N, Suárez C, González R, et al. Predictive variables for major bleeding events in patients presenting with documented acute venous thromboembolism. Findings from the RIETE Registry.. Thromb Haemost. 2008; 100 (1): p.26-31. doi: 10.1160/TH08-03-0193 . | Open in Read by QxMD
  32. Kearon C, Akl EA, Ornelas J, et al. Antithrombotic Therapy for VTE Disease. Chest. 2016; 149 (2): p.315-352. doi: 10.1016/j.chest.2015.11.026 . | Open in Read by QxMD
  33. Jaff MR, McMurtry MS, Archer SL, et al. Management of Massive and Submassive Pulmonary Embolism, Iliofemoral Deep Vein Thrombosis, and Chronic Thromboembolic Pulmonary Hypertension. Circulation. 2011; 123 (16): p.1788-1830. doi: 10.1161/cir.0b013e318214914f . | Open in Read by QxMD
  34. Konstantinides SV, Barco S, Lankeit M, Meyer G. Management of Pulmonary Embolism. J Am Coll Cardiol. 2016; 67 (8): p.976-990. doi: 10.1016/j.jacc.2015.11.061 . | Open in Read by QxMD
  35. Aujesky D, Obrosky DS, Stone RA, et al. Derivation and Validation of a Prognostic Model for Pulmonary Embolism. Am J Respir Crit Care Med. 2005; 172 (8): p.1041-1046. doi: 10.1164/rccm.200506-862oc . | Open in Read by QxMD
  36. Jiménez D, Aujesky D, Moores L, et al. Simplification of the Pulmonary Embolism Severity Index for Prognostication in Patients With Acute Symptomatic Pulmonary Embolism. Arch Intern Med. 2010; 170 (15): p.1383-9. doi: 10.1001/archinternmed.2010.199 . | Open in Read by QxMD
  37. Condliffe R, Elliot CA, Hughes RJ, et al. Management dilemmas in acute pulmonary embolism. Thorax. 2013; 69 (2): p.174-180. doi: 10.1136/thoraxjnl-2013-204667 . | Open in Read by QxMD
  38. Daley MJ, Murthy MS, Peterson EJ. Bleeding risk with systemic thrombolytic therapy for pulmonary embolism: scope of the problem. Ther Adv Drug Saf. 2015; 6 (2): p.57-66. doi: 10.1177/2042098615572333 . | Open in Read by QxMD
  39. Wilbur J, Shian B. Deep Venous Thrombosis and Pulmonary Embolism: Current Therapy.. Am Fam Physician. 2017; 95 (5): p.295-302.
  40. Douma RA, Mos ICM, Erkens PMG, et al. Performance of 4 Clinical Decision Rules in the Diagnostic Management of Acute Pulmonary Embolism. Ann Intern Med. 2011; 154 (11): p.709-18. doi: 10.7326/0003-4819-154-11-201106070-00002 . | Open in Read by QxMD
  41. Wells PS. Use of a Clinical Model for Safe Management of Patients with Suspected Pulmonary Embolism. Ann Intern Med. 1998; 129 (12): p.997-1005. doi: 10.7326/0003-4819-129-12-199812150-00002 . | Open in Read by QxMD
  42. Ceriani E, Combescure C, Le Gal G, et al. Clinical prediction rules for pulmonary embolism: a systematic review and meta-analysis. J Thromb Haemost. 2010 . doi: 10.1111/j.1538-7836.2010.03801.x . | Open in Read by QxMD
  43. Wells PS, Anderson DR, Rodger M, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer.. Thromb Haemost. 2000; 83 (3): p.416-20.
  44. Le Gal G, Righini M, Roy P-M, et al. Prediction of Pulmonary Embolism in the Emergency Department: The Revised Geneva Score. Ann Intern Med. 2006; 144 (3): p.165-171. doi: 10.7326/0003-4819-144-3-200602070-00004 . | Open in Read by QxMD
  45. Kline JA, Courtney DM, Kabrhel C, et al. Prospective multicenter evaluation of the pulmonary embolism rule-out criteria. J Thromb Haemost. 2008; 6 (5): p.772-780. doi: 10.1111/j.1538-7836.2008.02944.x . | Open in Read by QxMD
  46. Kline JA, Mitchell AM, Kabrhel C, Richman PB, Courtney DM. Clinical criteria to prevent unnecessary diagnostic testing in emergency department patients with suspected pulmonary embolism. J Thromb Haemost. 2004; 2 (8): p.1247-1255. doi: 10.1111/j.1538-7836.2004.00790.x . | Open in Read by QxMD
  47. Fineschi V, Turillazzi E, Neri M, Pomara C, Riezzo I. Histological age determination of venous thrombosis: A neglected forensic task in fatal pulmonary thrombo-embolism. Forensic Sci Int. 2009; 186 (1-3): p.22-28. doi: 10.1016/j.forsciint.2009.01.006 . | Open in Read by QxMD
  48. Becattini C, Agnelli G, Lankeit M, et al. Acute pulmonary embolism: mortality prediction by the 2014 European Society of Cardiology risk stratification model. European Respiratory Journal. 2016; 48 (3): p.780-786. doi: 10.1183/13993003.00024-2016 . | Open in Read by QxMD

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