A 45-year-old woman presents with sudden onset severe left-sided pleuritic chest pain and breathlessness. She returned from Australia 2 days ago after a 24-hour flight. She takes the combined oral contraceptive pill. She has no previous history of PE or DVT, no haemoptysis, and no active malignancy.
On examination:
- Respiratory rate: 28 breaths/min
- Heart rate: 115 bpm
- Blood pressure: 110/70 mmHg
- Oxygen saturation: 91% on room air
- Temperature: 37.2°C
- Right calf: Swollen and tender, 3 cm larger than left
Her ECG shows sinus tachycardia. Chest radiograph is reported as normal. The treating clinician considers PE to be the most likely diagnosis.
Using the original Wells score for pulmonary embolism, what is her probability category?
A
Low probability (0-1 points)
B
Intermediate probability (2-6 points)
C
High probability (>6 points)
D
PE unlikely — alternative diagnosis more likely
E
Score cannot be calculated without D-dimer result