Pulmonary Thromboembolism: NEET PG Essentials
1. Classic Radiographic Signs (Rarely normal, but often subtle)
- Westermark Sign: Focal area of oligemia (decreased vascular markings) distal to the pulmonary embolus.
- Hampton’s Hump: A wedge-shaped, pleural-based opacity representing pulmonary infarction.
- Palla’s Sign: Enlargement of the right descending pulmonary artery due to the clot.
2. Diagnostic Gold Standards
| Modality | High-Yield Utility |
|---|---|
| CT Pulmonary Angiography (CTPA) | Gold standard for diagnosis. Shows the “filling defect” within the pulmonary artery. |
| V/Q Scan | Used if CTPA is contraindicated (e.g., renal failure, severe contrast allergy). Looking for “ventilation-perfusion mismatch.” |
3. Clinical Pearls & Management
- Wells Score: Used to assess pre-test probability of PE (clinical features include DVT signs, tachycardia, immobilization, history of DVT/PE).
- ECG Findings: The most common is sinus tachycardia. Classic but rare: S1Q3T3 pattern (S wave in lead I, Q wave in lead III, T-wave inversion in lead III).
- Treatment (Massive PE): If hemodynamic instability (hypotension) is present, thrombolysis (e.g., tPA) is indicated.
- Treatment (Stable PE): Anticoagulation (e.g., LMWH, DOACs).
- Inferior Vena Cava (IVC) Filter: Indicated only if there is an absolute contraindication to anticoagulation or recurrent PE despite adequate therapy.