Differentials for Pulmonary embolism
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"pulmonary embolism"[MeSH Terms] AND "differential diagnosis"[MeSH Terms]
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Differentials for Pulmonary Embolism
PE classically presents with dyspnea, pleuritic chest pain, tachycardia, and hypoxia - but none of these findings is specific. The differential is best organized by the dominant presenting syndrome.
Braunwald's Differential Diagnosis Table (Table 87.5)
The following conditions are listed as the formal differential in Braunwald's Heart Disease:
| Category | Condition |
|---|---|
| Cardiac | Acute coronary syndromes, Decompensated heart failure, Pericardial disease (pericarditis/tamponade), Aortic dissection |
| Pulmonary | Pneumonia, Acute bronchitis, COPD exacerbation, Pneumothorax, Pulmonary hypertension, Intrathoracic malignancy |
| Other | Musculoskeletal pain, Hepatobiliary or splenic pathology, Anxiety |
Key Differentials in Detail
1. Acute Coronary Syndrome (ACS)
- Shared features: Chest pain, dyspnea, elevated troponin (RV strain in massive PE raises troponin), tachycardia, ECG changes
- Distinguishing: ST elevation/depression or new LBBB in ACS; PE more likely to show S1Q3T3, sinus tachycardia, T-wave inversions V1-V4 (right heart strain pattern). D-dimer elevated in both; troponin elevation in PE reflects RV strain, not coronary occlusion
- Key test: CTPA vs. coronary angiography; echo showing RV dilation favors PE
2. Aortic Dissection
- Shared features: Sudden severe chest pain, hypotension, shock, dyspnea
- Distinguishing: Dissection pain is maximal at onset, tearing/ripping quality, radiates to back; blood pressure differential between arms; widened mediastinum on CXR. Dissection can cause secondary PE or pulmonary involvement
- Key test: CT aortography (ECG-gated); note: thrombolytics given for PE can be catastrophic in dissection
3. Pneumothorax
- Shared features: Sudden dyspnea, pleuritic chest pain, hypoxia, tachycardia - can cause obstructive shock (tension pneumothorax)
- Distinguishing: Decreased breath sounds, hyperresonance on the affected side; hypoxia often severe; CXR shows absent lung markings with pleural line
- Key test: CXR (immediate); bedside ultrasound (absence of lung sliding)
4. Pneumonia / Community-Acquired Pneumonia
- Shared features: Dyspnea, tachycardia, pleuritic chest pain (parapneumonic), hypoxia, fever, cough
- Distinguishing: Fever more prominent; consolidation on CXR; productive cough; elevated WBC; no DVT signs. Note: pneumonia can coexist with PE
- Key test: CXR consolidation; CTPA if PE cannot be excluded
5. Decompensated Heart Failure
- Shared features: Dyspnea (exertional and at rest), tachycardia, hypoxia, bilateral pleural effusions (PE can also cause effusion)
- Distinguishing: Orthopnea/PND, peripheral edema, raised JVP, bibasal crackles, elevated BNP/NT-proBNP; pulmonary venous congestion on CXR
- Key test: Echocardiography (LV dysfunction vs. isolated RV dilation); BNP markedly elevated in HF (also elevated in massive PE but with RV pattern)
6. Pericarditis / Cardiac Tamponade
- Shared features: Chest pain, dyspnea, raised JVP (tamponade), tachycardia, ECG changes
- Distinguishing: Pericarditis pain worsened by lying flat, improved by leaning forward; friction rub; saddle-shaped ST elevation in multiple leads; in tamponade - Beck's triad (hypotension, raised JVP, muffled heart sounds), pulsus paradoxus. Rosen's notes PE can rarely mimic pericarditis
- Key test: Echocardiography (pericardial effusion); ECG pattern
7. COPD Exacerbation / Asthma
- Shared features: Acute dyspnea, hypoxia, tachypnea, tachycardia
- Distinguishing: Wheeze, prolonged expiration, increased work of breathing; known COPD/asthma history; hypercapnia common; responds to bronchodilators
- Caution: PE is a well-known precipitant of apparently unexplained COPD exacerbation; consider CTPA if no clear infective trigger
8. Pleurisy / Connective Tissue Disease-Related
- Shared features: Sharp, positional, pleuritic chest pain; dyspnea
- Distinguishing: Pleuritic rub; underlying CTD (SLE, RA); pleurisy alone does not cause hemodynamic compromise; fever, rash, arthralgia may be present
- Goldman-Cecil specifically lists pleurisy secondary to connective tissue disease as a differential
9. Musculoskeletal Chest Pain
- Shared features: Chest pain, may have localized tenderness
- Distinguishing: Reproducible tenderness on chest wall palpation; pain worsened by movement/palpation (costochondritis, rib fracture); no hemodynamic compromise; normal O2 saturation
- Caution: This is a diagnosis of exclusion - do not anchor on musculoskeletal pain in at-risk patients
10. Pulmonary Hypertension (Chronic)
- Shared features: Progressive dyspnea, hypoxia, RV strain, syncope, raised JVP, ECG showing RV changes
- Distinguishing: Insidious onset vs. PE's acute presentation; history of gradually worsening symptoms; loud P2; no acute precipitant. CTPA shows no filling defect; V/Q scan may show diffuse heterogeneous perfusion defects
- Note: Acute PE can precipitate acute-on-chronic pulmonary hypertension
11. Anxiety / Panic Attack
- Shared features: Dyspnea, chest tightness, tachycardia, hyperventilation, low CO2 (respiratory alkalosis)
- Distinguishing: No hypoxia on pulse oximetry; no pleuritic pain; normal ECG/D-dimer/CXR; situational trigger; prior history of panic disorder
- Caution: Anxiety is a diagnosis of exclusion - Wells score and D-dimer must guide workup
Distinguishing Features Summary
| Feature | PE | ACS | Dissection | Pneumothorax | Pneumonia |
|---|---|---|---|---|---|
| Onset | Sudden | Sudden | Instantaneous | Sudden | Gradual |
| Pain character | Pleuritic | Pressure/squeezing | Tearing, to back | Sharp, pleuritic | Pleuritic |
| Hypoxia | Yes | Mild | Possible | Yes | Yes |
| DVT signs | May be present | Absent | Absent | Absent | Absent |
| CXR | Near-normal, Westermark sign, Hampton hump | Pulmonary edema | Wide mediastinum | Absent lung markings | Consolidation |
| D-dimer | Elevated | Often elevated | Elevated | Normal | May be elevated |
| Key test | CTPA | ECG, troponin, angio | CT aortography | CXR, ultrasound | CXR, cultures |
Clinical Pearl
As noted in Goldman-Cecil Medicine, no single symptom or sign confirms or excludes PE. Risk stratification with the Wells score (or Geneva score) combined with D-dimer testing is mandatory - in patients with low-to-moderate pretest probability and a negative D-dimer, PE can be excluded without imaging. High pretest probability or a positive D-dimer requires CTPA.
Sources: Braunwald's Heart Disease (Table 87.5), Goldman-Cecil Medicine (Ch. 68), Fuster & Hurst's The Heart (15th ed.), Rosen's Emergency Medicine
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