A 55 year old man who has been on bed rest for the past 10 days, complain of breathlessness and chest pain. The chest X-ray is normal. The next step in the investigation should be –

This patient has a high clinical likelihood of pulmonary embolism because clinical assessment score is more than 4:- Signs & symptoms of PE (Breathlessness & chest pain) → score 3.0 Immobilization (bed rest) > 3 days → score 1.5 So, the total score is 4.5. Therefore, imaging test should be done. CT contrast is the imaging test of choice.